flat belts

Compendium
FLAT BELTS

Siegling – total belting solutions

1 S iegling –total belting solutions.  .  .  .  .  .  .  .  .  .  .  .  .  .  . 51.1 Company and group. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
1.2 Products and markets. . . . . . . . . . . . . . . . . . . . . . . . . . . . .  7

2 Siegling Extremultus flat belts .  .  .  .  .  .  . 92.1 History of flat belts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
2.2 Design and materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . .  16
2.3	Electrostatic properties. . . . . . . . . . . . . . . . . . . . . . . . . . .  20
2.4 Food properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  22
2.5 Nomenclature and Datasheet. . . . . . . . . . . . . . . . . . . . .  23
2.6	
General properties of force-fit belt drives. . . . . . . . . .  24
2.7 Force-fit belt drives in comparison. . . . . . . . . . . . . . . .  26
2.8 Special strengths of flat belts. . . . . . . . . . . . . . . . . . . . .  28
2.9 Application groups. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  30

3 Chemical resistance .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 35
3.1 General information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.2 Chemical resistance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  37

4 Belt selection .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 41
4.1 General information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  42
4.2 Tension member. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  43
4.3 Coating materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  44
4.4 Extremultus Product Finder. . . . . . . . . . . . . . . . . . . . . . .  46
4.5 B_Rex Calculator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  47

5 Manufacturing data.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 49
5.1 Manufacturing tolerances . . . . . . . . . . . . . . . . . . . . . . . . . 50
5.2 Delivery dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

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6 Handling flat belts .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 53

10 Calculation of Live Roller Belts .  .  .  .  .  .  . 99

6.1 Storage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  54

10.1 General information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

6.2 Condition of machinery . . . . . . . . . . . . . . . . . . . . . . . . . .  55

10.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

6.3 Fitting and tensioning. . . . . . . . . . . . . . . . . . . . . . . . . . . .  56

10.3 Calculation method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

6.4. Maintenance and handling. . . . . . . . . . . . . . . . . . . . . . .  63

11 Troubleshooting .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 107
7 Splicing and fabrication technology. .  . 65

11.1 Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

7.1 General information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

11.2 Splice opening. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  109

7.2 Splice types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

11.3 Noise generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  110

7.3 Splicing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  70

11.4 Poor belt tracking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

7.4 Fabrication options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

11.5 Wear. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  11311.6 Changes in properties. . . . . . . . . . . . . . . . . . . . . . . . . . .  115

8 Pulleys .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 75
8.1 Pulley geometries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

12 Glossary.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 117

Dimensions and quality of pulleys . . . . . . . . . . . . . . . . . 78
8.2	
8.3 Use of crowned pulleys. . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

9 C
 alculation of
power transmission belts.  .  .  .  .  .  .  .  .  .  .  . 81
9.1 General information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  82
9.2 Power transmission on flat belts . . . . . . . . . . . . . . . . . .  83
9.3 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
9.4. Calculation method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
9.5 Operating factor c2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
9.6 Basic elongation at fitting c4. . . . . . . . . . . . . . . . . . . . . . . 87
9.7 Elongation allowance for centrifugal force c5. . . . . . . 92
9.8 Vibration calculation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
9.9 Calculation example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

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13 Legal notes.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 126

Not always visible, yet present everywhere,
Forbo Movement Systems makes sure that yourlogistics and production workflow run smoothly andoptimally. Our solutions are characterized by a highlevel of efficiency, precision and reliability. We are inglobal demand as an expert partner in the developmentof industry-specific and future-oriented solutions fordrives, conveyor systems and manufacturing.

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1 Siegling –Total belting
	solutions
1.1 Company and group
1.2 Products and markets

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1.1 Company and group

Forbo Movement Systems is a division of Forbo Holding AG.
The company’s headquarters is located in Baar, Switzer­land,in the Canton of Zug. The company is listed on the
SIX Swiss Exchange. Forbo is a global player whose twodivisions, Forbo Flooring Systems and Forbo Movement
Systems, serve a wide variety of industries and markets.
The Movement Systems division has risen to a leading position worldwide as a provider of high-quality conveyor andprocessing belts, plastic modular belts, first-class powertransmission belts and both toothed and flat belts made ofsynthetic materials. These belts are used in a wide variety of6Extremultus Compendium · 01/2019

applications in both industry and commercial enterprises
and service companies, for instance as conveyor and processing belts in the food industry, as treadmills in gyms or
as flat belts in letter sorting systems.
Movement Systems employs more than 2500 people andhas an international network of companies and represent­
atives with materials warehouses and workshops in over
80 countries.

1.2 Products and markets

The increasing globalization of markets requires an innovative approach to production, materials flow andlogistics; conveyor belts, processing belts and power transmission belts often play a key role in this process.
We keep the world running with these products.

Our products
siegling transilon… are multi-layered and fabric-based belts, or belts madefrom homogeneous materials. They ensure efficientmaterials flow and economical process flows in all areasof light conveyor technology.

siegling transtex… are multi-layered, fabric-based belts with a particularlyrobust design, and are therefore the preferred solution forheavy-duty conveying.

siegling extremultus… are multi-layered and fabric-based power transmission
belts, or belts made from homogeneous materials. Whenused for power transmission and conveying, they optimize
power transmission and numerous production processes.

siegling prolink… are plastic modules connected by hinge pins and withvarious designs. They are often ideal for combining
conveying and processing.

siegling proposition… are form-fit belts made from homogenous plastics andwith various tension members; they are perfect for challenging acceleration, timing and positioning processes.

conveyor and processing belts

conveyor belts

flat belts

modular beltstiming belts

Our main markets are■ Food industry■ Logistics, airports■ Industrial production■ Raw materials■ Textile industry■ Paper industry■ Printing industry■ Sport and leisure■ Tobacco industry

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Food processing, agriculture and packaging sectors
Intralogistics, distribution centers, baggage sorting
Automotive, tires, chemicals, energy, steel- and metalworking industries
Building materials, wood and stone
Yarn manufacturing, nonwovens, textile printing
Paper production and processing as well as letter sorting
Rotary printing, sheet-fed printing, digital printing and post-press
Treadmill belts, belts for ski lifts and other leisure activities
Raw tobacco and cigarette manufacturing

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Extremultus
FLAT BELTS
2.1 History of flat belts
2.2 Design and materials
2.3 Electrostatic properties
2.4 Food properties
2.5 Nomenclature and Datasheet
2.6 	General properties of force-fit belt drives
2.7 Force-fit belt drives in comparison
2.8 Special strengths of flat belts
2.9 Application groups

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2.1 History of flat belts
The industrial revolution
In pre-industrial times, the forces ofnature were harnessed using axles,
gears and drive mechanisms likechains and ropes. Normally, a con­nection was established between
the generator and a single consumer:from the windmill vane to the grind­stone, from the draft animal to thescoop wheel, from the water wheel
to the forging hammer. This principle
endured for thousands of years –until, completely independent ofwind energy or hydropower, thesteam engine offered such greatmechanical power on demandthat many consumers could be
supplied at the same time.

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At the time of their invention at
the beginning of the 18th century,
the first steam engines were still very
inefficient. It wasn’t until 1769 when
James Watt patented his invention of
the double-acting piston, increasing
efficiency tremendously. During thecourse of the 19th century, efficiency
continued to improve thanks to anumber of inventions, designs be­­came more compact and use became
more effective. The spread of thesteam engine sparked the industrial
revolution in the factories. With its
triumph, the flat belt appeared con­fidently on the scene. Individual pro­duction machines were driven by steel
shafts on the hall ceiling, pulleys andflat transmission belts made of leather.

Transmission belts were the simple andreliable link between the steam engine
and the new mechanical inventions of
the time: e.g. machine tools, spinningmachines and mechanical looms.
Flat belts were used for power trans­mission well into the 20th century,even for agricultural machinery andvehicles (the first ones were operated
with steam engines).

Production building 1906.
Each of the processing machines is driven
by a central transmission shaft underneaththe building’s ceiling.

Siegling shapes flat belt development
In 1919 Ernst Siegling founded atransmission belt factory in his name in
Hanover and shortly thereafter began
producing flat belts made of leather.
At the start of the 1920s, he helpedwith the breakthrough of a new flat
belt design: the upright chrome leather
belt. Upright leather belts were con­nected crossways to the direction of
movement using rivet pins. This madethe belt particularly robust, even andefficient. With lower shaft loads it
offered higher power transmission
and less slip.

Above:
Design of the chrome leather upright belt
(illustration from 1925).
On the right:
Ernst Siegling
On the left:
Ernst Siegling with some of his workforce
in the 1920s.

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2.1 History of flat belts

However, the disadvantages of natural
leather were still evident: leather
stretches over time which means thatthe belts have to be shortened atregular intervals. On top of that, thebelts were not particularly dimension­
ally stable and were sensitive to mois­
ture. At the same time, industrial buy­
ers were becoming more demandingin terms of their technical require­ments. The advent of motors increas­
ingly suppressed energy distribution
via transmissions and single drive toolmachines became the norm. Flat belts
were now in stiff com­petition withother transmission variants.
Ernst Siegling continued to con­sistently develop his range of flat belts.
The beginning of the 1930s saw the
introduction of the first flat belts withadhesive coatings and in 1939 thefirst electrically conductive belts forhazardous areas followed under thename “non-el-stat”.

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The development of a multi-layered
polyamide and chrome leather flat belt
at the beginning of the 1940s wasa technical milestone. A highly orien­tated polyamide sheet served as thetension member and a thin chromeleather layer as the surface. This belt
construction combined the advan­
tages of both materials and is stillwidely used today. Boasting at least
98 % efficiency, this construction
re­presented a significant increase inenergy efficiency compared to con­ventional belt and chain drives. Thisdevelopment was patented in 1943,
launched on the market as Extremultus
and sold all over the world from thelate 1940s.

Ernst Siegling died in 1954, whereupon
his son Hellmut Siegling took over thecompany and successfully carried on
the concept of the multi-layered flat
belt. In addition to the tried and true
polyamide band, a variety of otherfabric tension members came into
use. The chrome leather coating also
underwent numerous changes.
Diversification led to the creation of
new products that have since become
indispensable to a variety of industrial

sectors. Even the development ofa fabric-based plastic conveyor forinternal materials flow (Transilon) in
the 1960s, groundbreaking at the time,
was based on years of experience andknowledge of flat belts.

2.1 History of flat belts

In 1994, the Forbo Beteiligungs GmbH
took over the shares previously ownedby the family. The company continued
on its path to globalism, adding new
production and assembly sites incountries including China. Rigorous
research and development work
drove the development of flat belts
that perfectly supported produc­

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tion processes while performing theirfunction as drive elements. Siegling
Extremultus flat belts are prime exam­
ples of this, boasting outstanding grip
for converting paper and cardboard(Grip Star™) as well as belts for electro­
static discharge (ESD) areas in theelectronics industry (Flash Star™).

Flat belts today
Today’s descendants of the old transmission belts are high-tech products that
contribute significantly when it comes to efficient and smooth operation in awide variety of industrial drive and production processes. Their rapid evolution
and the state of their development today are evident in their impressive key data:
Tensile strength
The tensile strength increased from30 N/mm2 for core leather belts toapprox. 500 N/mm2 for flat belts witha polyamide tension member. Today,
values of approx. 800 N/mm2 are easily
achieved when polyester materials areused. This type of improvement meantthat considerably more compact, morecost-effective belt drives were inevita­
ble. The power transmitted per mmof belt width is approx. 30–40 kW/mm,
assuming good operating conditions
and corresponding belt speeds.
Belt speed
The maximum belt speed for coreleather belts topped out at approx.
35 m/s. With the belt constructions
common today, speeds up to 100 m/s
are not uncommon. Speeds of up to
200 m/s can be achieved on engine
test stations over a prolonged periodof time. Siegling Extremultus flat belts
with tension members made of end­
less cord without splicing are used insuch cases.

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Bending frequencies
Core leather belts were limited toapprox. 40 bending cycles per second.
Today, Siegling Extremultus flat belts
with tension members made of end­
less cord (polyester cord) allow approx.
250 bending cycles per second with­out limiting service life.
No maintenance or re-tensioning
The materials used as tension mem­bers today (polyamide, polyester andaramide) retain tension following
relaxation, eliminating the need forre-tensioning or shortening the
Siegling Extremultus flat belts during
operation. Effective material com­binations consisting of plastic tension
members and elastomer coatingsrequire no maintenance. Only flat belts
with chrome leather coatings must
be maintained at certain intervals.
However, a special spray makes main­
tenance extremely easy and clean.

2.2 Design and materials
Structural diagram of a flat belt
Top face
Tension member
		Underside

Tension member design

Fabric in warp and weft16

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Sheet (highly oriented)
or Foil (elastic)

Truly endless cord

The diagram (page 16) depicts the construction of a flat belt made up of a tension member as well as coatings on the
top face and the underside. Depending on the choice of material and the sub-type etc., flat belts have very different
properties, making them suitable for a wide variety of applications.

Tension member

Surface pattern

The technical properties of a flat belt are pri­mari­ly
determined by its tension member. For this reason,
Siegling Extremultus flat belts with the same tension
member materials are grouped in product lines.

Tension member materials
A = Aramide line
E
= Polyester line
P = Polyamide line
U = Polyurethane line

➀

➁

➂

➃

➄

➅

Coating
The coatings are in direct contact with the drive pulleys(generally the underside of the belt) and, where necessary,with the product to be conveyed (generally the top face ofthe belt). Skillful selection of the material and surface pattern make it possible to determine contact-specific properties such as grip, chemical resistance, electrostatic properties
and food compliance.

Coating materials
G = G elastomerL= Chrome leather
N =	Novo (nonwoven
polyester material)
P = Polyamide
R = High/Medium gripT=	Fabric (Polyamide,
Polyester, mixed)
U = Polyurethane

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Extremultus Compendium · 01/2019➆➀ FBRC fabric➁ FSTR fine texture➂ GL smooth➃ GSTR coarse texture➄ LTHR leather➅ NP inverted pyramid texture➆ NSTR normal texture

Typical combinations
Not all combinations of tension members and coating
materials are practical. Years of experience with the use offlat belts in a variety of applications have led us to offer
the current combinations seen below:

Abbreviation

Product line

A

Aramide line

E

Polyester line

P

Polyamide lineU

Polyurethane line

Tensionmember design

CoatingFabric

G, U

Cord

G, L, T

FabricG, N, P, R, T, U

Cord

G, L, T, U

FabricG, N, T, U

Sheet

G, L, N, R, T, U

Foil

G, R, U2.2 Design and materials

Aramide line

Polyester line

Flat belts with a tension member made from mixed fabricwith aramide yarn in the direction of tension are especially
flexible and extremely strong. They can be spliced directlyon the machinery.

Flat belts featuring a polyester fabric tension member are
the best choice for many applications. They are particularly
flexible and strong at the same time and can be spliced on
the machinery.

Flat belts with a tension member made from truly endlessaramide cord have no splice to ensure particularly smooth
tracking.

Flat belts with a tension member made from truly endlesspolyester cord have no splice to ensure particularly smooth
tracking.

Siegling Extremultus flat belts of the Aramide line aredesigned for extremely high effective pull and extremely
short take-up ranges. The aramide line must be handledwith great care as the aramide fibres can easily be bent.

Polyester line Siegling Extremultus flat belts can transmit
high circumferential forces with simultaneously shorttake-up ranges. In addition, they are shock-resistant andnot susceptible to fluctuations in climate.

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Polyamide line

Polyurethane line

Flat belts with a tension member made from highlyorientated polyamide sheet boast particularly strong
edges, are laterally stiff and durable.

Flat belts with a tension member made of highly elastic
polyurethane foil are elastic, highly flexible and boast
excellent damping capabilities. Due to their flexibility,
Siegling Extremultus flat belts in the polyurethane line havegood tracking characteristics and are particularly well suitedfor machinery with short center distances, manual take-up
units and small drum diameters.

Flat belts with a polyamide fabric tension member areespecially flexible and feature relatively high tensile strength.
Polyamide is characterized by its outstanding damping
capabilities. The hygroscopic properties of the polyamide
material make it important to take into account extreme
climatic fluctuations during storage and use.

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In addition, the polyurethane flat belts are 100 % fray free andvery easy to clean. That makes them perfect for use in areas
where hygiene is vital.

2.3 Electrostatic Properties

It is essentially impossible to avoid static electricity whenusing power transmission and conveyor belts. It is createdthrough the contact and subsequent separation of different
materials (triboelectric effect), and can also be imported
into the system by the conveyed product.
The consequences of electrostatic charging anduncontrolled discharges may be:– Disruptions in production while processing foils
and paper when the goods to be processed adhereto each other or to the belt
– Contamination through dust, lint, etc.

Static electricity through the conveyed product and the triboelectriceffect.

– Electric shocks– Damage to electronic components(conveyed product and machine components)– Fires and explosions
The goal for every power transmission and conveyor
system must thus be to discharge the electrostatic charge
in a controlled manner.

Hazards due to uncontrolled discharge of static electricity.

Controlled discharge of static electricity by selecting the correct flat belt

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An antistatic feature is standard for Siegling Extremultus
flat belts. Siegling Extremultus flat belts with special
electrostatic properties are required for some applications.
Products with the “NA” symbol are used in situations inwhich conductive components could disrupt the appli­
cation, e.g. in metal detectors. All antistatic products
contain elements that guarantee longitudinal conductivity.
Products with a highly conductive surface are marked as“HC”. The “HC+” symbol denotes all Siegling Extremultus flat
belts that, in addition to their highly conductive surfaces,
are also highly conductive in all three directions. These
products are also assigned to the Flash Star™ product line,
in other words the ESD-compliant flat belts.
www.forbo.com/movement > Products > Flat Belts >Flash Star
Under certain conditions, Siegling Extremultus flat belts
may be used in hazardous areas classified according to
ATEX. Upon technical clarification and ultimate judge­
ment by application support, Forbo Movement Systems canprovide appropriate ATEX manufacturer declarations forindividual products.
Observe European and relevant national regulations on
explosion protection: 94/4 EC 2014/34/EU (ATEX), ISO
80079-36 and 37, BGR 132 of the Accident Prevention andInsurance Association for the German Chemicals Industry“Guidelines for the avoidance of ignition risks following
electrostatic discharge”.

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Non-antistatic (NA)Belt material with isolating properties.
Antistatic (no special abbreviation)
Belt material with electrically conductive components within the belt
or on the surface.
Conductivity of the whole belt lengthways RDi < 3*108 Ω.
Highly conductive (HC)
Conductive top face, usually conductive underside too.
Must be antistatic as well.
Conductive on the surface lengthway ROB < 3*108 Ω.
Highly conductive plus (HC+)
Conductive top face, underside and through the belt too.
Has to be highly conductive on both sides.
Conductive right through the belt RD < 109 Ω.

Flash Star™

2.4 Food Properties

Observe the various regional laws/regulations when using
Siegling Extremultus flat belts in the food industry. The flat
belts bearing the FDA and HACCP acronyms are particularly
well suited for contact with unpacked food:Siegling Extremultus flat belts bearing the FDA symbol aresuitable for the transport of unpacked food as per FDA 21
CFR. Beyond that, these products also generally meet therequirements of European Ordinance (EU) 10/2011 and(EC) 1935/2004. Please always observe the information on
the relevant data sheet.
We will support your HACCP concept reliably and in compli­
ance with legal requirements in all areas where hygiene isvital. Siegling Extremultus products with the HACCP desig­
nation boast a range of special product properties and subtypes. These components close any potential safety gaps in
the manufacturing process.

Convey and process

food safely

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Due to their excellent release properties, HACCP products
are extremely advantageous when it comes to processing
food with adhesive properties. Forbo Siegling offers belts
with a unique surface finish to transport goods with a par­ticular tendency to stick. They boast excellent release prop­
erties when it comes to particularly sticky products such as
dough, caramel and other candy and they are easy to clean.
Contact your local representative for more information
about products suitable for food:www.forbo.com/movement > Contact
You can find the certificates for the declarations of confor­
mity on our website:www.forbo.com/movement > Download > Declarationsof Compliance2.5 Nomenclature and Datasheet
Nomenclature

N

N

4

P

G

G

14

P

855646

U

U

20

U

855647

U

R

40

U

HC+

NSTR

HC

FBRC

FSTR

grey

NSTR

/

black

/

blue

Food
properties

855635850325

14

/
/

Color
top face

E

T

NSTR

Color overall
or underside

E

15

R

82215925

Surface pattern
top face

4T822154

–
–
–
–
–
–
–

Surface patternoverall orundersideR

GElectrostatic
property

Tension member
material
A

822130Total thickness[1/10 mm]

Type number
25

Coatingunderside

G

Article No.

Coating
top face

Siegling Extremultus flat belts are named based on a helpful, transparent nomenclature. Both the structure and theimportant properties of the belt can be identified directly from the nomenclature. The following table features sometypical examples.

grey
black

HC+

grey

40

green

9

GSTR

12

FSTR

/

FSTR

black
blue

HACCP FDA
FDA

Note: Not all of the information is always found in the nomenclature of individual products, as the nomenclature has grownover time. The exact and complete information for each product can thus be found in the current data sheet.

Data sheet
The data sheet contains all of the important information
about the Siegling Extremultus flat belts in a clear, easily
understandable way.

The information on the data sheets for the Siegling
Extremultus flat belts is divided into the following groups:– Available delivery width– Design

Data Sheet– Technical data

RR 4E-HC+ NSTR/NSTR
grey Sheet
Data
RR 4E-HC+ NSTR/NSTR
grey Sheet
Data
RR 4E-HC+ NSTR/NSTR
grey
Order information
Article number
Standard delivery width
Maximal delivery width (without
longitudinal seam) on request
Construction
Surface material top face
Surface pattern
Colour
Surface material underside
Surface pattern
ColourTension member material

822154450 mm/ (18 in)
Properties
1350Troughable
mm / (53 in)

Suitable for accumulation
Particular surface properties
One or two sides with non-marking
MediumGrip for sensitive goods
properties
NormaltextureAbrasion-resistanceof surface with
Greyconstant grip
Improved ageing resistance
MediumGrip
Normal texture
GreyFood properties
Mixed fabric, highly flexible

Technical data
Total thickness– PropertiesNo
No Applications► Medium
Grip office
ConveyingYes Packaging

Franking machines
Packaging machines
Paper Manufacturing
Envelope machines
Yes
Paper Manufacturing, Packaging
Carrier belt for paper and packaging
Letter sorting machines
Yes Postal
Printing
Automatic labellers; Folders newspaper(coldset); Post press (compensatingstackers, bundlers); Sheet-fed printing
Not suitable for the transport of unpacked (folding machines, sheet feeders, sheet
dischargers)
food according (EU) 10/2011 and (EC)1935/2004, FDA 21CFR or MHLW 370.

– Food properties– Electrostatic properties

Application Group
Machine Tapes
1.35 mm ± 0.1
Electrostatic(0.053in ± 0.004)properties
Highly conductive+
Conductive
top face and underside,
1.4 kg/m²
Remarks
additionally conductive across the belt
(0.287 lbs/ft²)
Grip Staris offered
thickness.
HC (TM)
properties
haveastoHighbe Grip or Medium Grip in different thicknesses
Fw‘ at 1 % elongation at fitting
4 N/mm / (22.84 lbf/in)
andfor
withappropriate
structures. The belts are suitable, especially if afulfilledboth
surfaces. surface
Conductivity
goodexactR(D)positioning,high acceleration or rapid deceleration is
Relaxed specific shaft load at 1 % elongation at fitting and 180° arc of contact in acrossthegrip-level,
belt thickness< 10^9 Ω.
needed.
N/mm belt width.
Flash Star (TM) belts support an ESD compliant sytem due to their excellent
k1% value relaxed
2 N/mm / (11.42 lbf/in)
conductivity in all three spatial directions. Undesired effects could be avoided,
Elongation at break longitudinal
15 %e. g. adhesion between the conveyed goods, pollution, electrostatic shocks.
Fabrication
Nominal effective pull (Fu',Nenn)
3 N/mmBelt edge sealing
Smartseal
Elongation at fitting min.
0.3 %
Yes
Elongation at fitting max.
2 % Profiles on top face
Yes
Friction coefficient of top face against 1.6 Profiles on underside
steel panel according to internal test
instruction
Minimum drum diameter
Friction coefficient of underside
1.6 Z-splice (35 x 11,5 mm) with counter- 14 mm / (0.6 in)against steel panel according tobending Øinternal test instruction
Z-splice (35 x 5,75 mm) with counter- 14 mm / (0.6 in)
Permissible operating temperature-20/70°C
bendingØ(-4/158 °F)
Z-splice (70 x 11,5 mm) with counter- 14 mm / (0.6 in)bending Ø
Remarks
10 mm possible up to max. 2,8 m/s
Weight– Fabrication– Minimum pulley diameter– Applications– Comments

The physical data in this data sheet is approximate, can alter depending on production environments and was established at standard ambientconditions (23°C/73°F, 50% relative humidity) in accordance with DIN 50014/ISO 554. Fluctuations in climate can cause variations. See ourbrochure “Technical Information 1” no. 317 which shows the types of belts that can be supplied and the manufacturing tolerances. Customised
types require written confirmation.
Date of last change: 9/30/2015

Siegling - total belting solutions

The physical data in this data sheet is approximate, can alter depending on production environments and was established at standard ambientconditions (23°C/73°F, 50% relative humidity) in accordance with DIN 50014/ISO 554. Fluctuations in climate can cause variations. See ourbrochure “Technical Information 1” no. 317 which shows the types of belts that can be supplied and the manufacturing tolerances. Customised
types require written confirmation.
Date of last change: 9/30/2015

Siegling - total belting solutions

The physical data in this data sheet is approximate, can alter depending on production environments and was established at standard ambientconditions (23°C/73°F, 50% relative humidity) in accordance 1
with DIN 50014/ISO 554. Fluctuations in climate can cause variations. See ourbrochure “Technical Information 1” no. 317 which shows the types of belts that can be supplied and the manufacturing tolerances. Customised
types require written confirmation.
Date of last change: 9/30/2015

Siegling - total belting solutions

2
3

Note: You can find the data sheets for all of the Siegling Extremultus flat belts in the Product Finder (see Chapter 4.4). Whensearching for a flat belt, select “Details” and “Show data sheet” to open the respective data sheet. You can find the Product Finder
for the Siegling Extremultus flat belts at:www.forbo.com/movement > E-Tools

23

Extremultus Compendium · 01/2019

2.6 General properties offorce-fit belt drives
Force-fit belt drives belong to the group of traction drives.
Due to the pretension or shaft load FW and the friction μ
between belts and pulleys, it is possible to transfer an effective pull FU from the driving pulley (1) to the driven pulley (2)with the help of the traction drive – the belt. Traction forces
F1 and F2, which must be absorbed by the belt construction,
are created in flexible, elastic belts.
A variety of belt types are used in force-fit belt drives:– Flat belt
– V-belt– V-ribbed belts or

A certain phenomenon occurs in all force-fit belt drives:
the rotations per minute – and the circumferential speed –on the driven pulley is slightly slower than the theoreticallycalculated value. This load-dependent loss is referred to as
slip. A slip of up to 0.9 % is referred to as creep. Creep occurs
during normal belt operation and describes how the elasticity of the tension member compensates for the different
forces and tensions in the two belt strands. Slip values
above 0.9 % are known as slippage. This is when the belt
slips over the pulley. Both the transmission of power and theservice life of the belt suffer when this occurs. Therefore,
avoid operating the force-fit belt drive in the slippage areaat all costs.

– round belts.
Regardless of the exact design and the traction belt used,
force-fit belt drives have a number of things in common:– technically uncomplicated, compact andcost-effective design– large centerdistances, limited axles andmulti-pulley drives possible– traction drive generally easy to install andcan be replaced– virtually maintenance-free– good damping properties andthus good vibration insulation– lower noise level than mechanical gears– no chordal action when transmitting power(compared to chains)
Representation of the transmissionof power in a force-fit belt drive.

F1
FU

FW

F2

24

Extremultus Compendium · 01/2019

Slippage does, however, offer one great advantage overform-fit drives. In the event of unpredicted peaks in power,
the belts simply slide off the force-fit belt drives, preventing
more serious damage to the machinery and retaining theirability to function afterwards. Form-fit drives such as timing
belt drives and gear drives require an expensive coupling todo this, e.g. a slip coupling to withstand peaks in power
without damage.
Further losses, in addition to the slip, are generated during
operation, depending on the shape and structure of the
traction drive as well as the geometry of the pulleys. These
losses include hysteresis and edge friction.
Edge friction only occurs between profiled belts such as
the V-belt and the V-ribbed belt and their correspondingly
shaped pulleys. Losses occur when the wedge or wedges
are pulled into the pulley grooves and must be pulled out
when running out of the grooves.
Hysteresis can be observed with all pulleys and describes
the conversion of a small part of the kinetic energy into
internal energy or heat inside the traction drive.

25

Extremultus Compendium · 01/2019

Furthermore, a force-fit belt drive is a system capable of vib­
ration, similar to a taught guitar string. When designing thedrive it is therefore important to consider the external influ­
ences that could potentially stimulate vibration in the sys­tem. Chapters 9 and 10 explain in detail how to carefully
design a flat belt drive.
In addition to these similarities, there are also significant
differences between the different force-fit belt drives,primarily due to different traction drive constructions.
A table in Chapter 2.7 lists and compares the main featuresof force-fit belt drives for flat belts, V-belts and V-ribbed
belts.

2.7 Force-fit belt drives
in comparison			Flat belt

V-beltV-ripped belt

Rotations per minute max. [min-1]
130,000
10,00012,500Circumferential speed max. [m/s]
200
50
60
Bending frequency max.	
[Hz]
>250
100
200
Temperature range[C°]	-50/+100	-35/+80	-35/+80
Power limit[kW]
5,000*
3,000
1,000
[%]
Efficiency
>98
96
96
Friction losses
lowlow– due to slip		low– due to edge friction		
none
relatively highrelatively high– due to hysteresis

low

Transmission		
up to 1:12
Transmission ratio 		variable			(cone belt drive)
Endless splicing 		common practicein the machinery			
Pulley geometry		simple

relatively highlow

up to 1:12
variable(variable speed pulleys)
possible (15 % less powertransmission)
complexup to 1:35
constant
not possible
complex* Generally possible, power limit depends on materials used. Observe information for respective flat belts. Please direct any questions to a
Forbo Movement Systems contact person.
Round belts are not used for power transmission and are thus not included in this comparison.
Sources:– VDI 2758: Riemengetriebe (June 1993)– Peeken, Troeder, Fischer: Wirkungsgradverhalten von Riemengetrieben im Vergleich, Antriebstechnik 28 (1989) Nr. 1, pp. 42 – 45

26

Extremultus Compendium · 01/2019

Efficiency of a flat belt.
Siegling Extremultus flat belts have an
efficiency of 98.6 %.
100
99
Efficiency [%]98

Source:German Federal Institute for Materials Testing:„Untersuchungen an Riemengetrieben –Bericht zur Hannover Messe“ (1984)

Siegling Extremultus flat belt

97
96
95
94

V-belt93

Power ratio P/PNenn [%]A set of V-belts
Slight variations in individual belt lengths
result in:– excessive slip
– different effective radii– different tensions– possibly jerky elongation compensation– asymmetrical rotation– increased edge friction

Higher friction losses when the
V-belt pulleys are misaligned.

27

Extremultus Compendium · 01/2019100

2.8 Special strengths of flat belts

Flat belt drives can be used at high speeds, can transmit high power and are extremely efficient. In addition to the key
technical information illustrated in Chapter 2.7, they boast other interesting advantages.

Versatile and simple drive design

High efficiency

Due to their great flexibility and the option of using bothsides of the belt for drive tasks, flat belts can be used ina wide variety of drive configurations (see series of figureson next page).

Flat belts are significantly more efficient than V-belts andV-ribbed belts. This is mainly due to friction losses. In
ad­dition to losses resulting from slip and hysteresis, which
are minimal with flat belts and at times considerably higher
with V-belts and V-ribbed belts, the edge friction present
with V-belts and V-ribbed belts can also lead to friction loss­
es. The more pronounced the wedge, the higher the con­tact surface between the edges of the wedge and thepulley. As the contact surface increases, so too does theedge friction and the friction losses.

As flat belts are custom made, there is no need to adhere
to standardized lengths and widths when designing thedrive. Due to their flat design, flat belts enable relatively low
drum diameters. The even surface also makes the drive anddrum pulleys easy to manufacture and thus cost-effective.

Long lifetimes
Flat belts boast long lifetimes due to their high abrasion
resistance. The constant friction coefficient guarantees
constant RPMs across the entire service life. The materials
used for tension members (polyester, aramide and poly­amide) maintain their tension extremely well, necessitating
re-tensioning in exceptional cases only. Flat belts withplastic tension members and elastomer coatings aremaintenance-free.
Chrome leather coatings, used mainly for heavy duty
drives, must be treated from time to time with a special
spray paste in order to maintain smooth tracking andslip behavior (see Chapter 6.4).

28

Extremultus Compendium · 01/2019

When it comes to flat belts, the loss of efficiency as aresult of slip is so minimal that the efficiency (> 98 %) isin the range of form-fit drives such as timing belt drives
and gear drives and sometimes even greater.

Low operating noises
Flat belts produce high-frequency, low-amplitude noise.
The coating on the underside of the belt can minimize
noise, e.g. select a chrome leather layer or texture theelastomer layer. That is why flat belts generate considerably
less operating noise than V-belts or V-ribbed belts.

Wide range of application
Practically speaking, considering flat belts as pure drive
elements often falls short. In addition to the classicaldrive function, they also provide great support whenit comes to industrial (production) processes; e.g.
processing boxes.
Flat belts have also been performing conveyor tasks foryears. This has been primarily in the field of electronics
and the food industry, including the manufacture of solar
cells and the production of baked goods. These processes
are far too complex for other types of belts.

➀

➁

➂

– Flat belts are the only ones that can execute thenecessary, sometimes highly complex, belt processes.
➃– Only flat belts have such a wide range of different
characteristics at their disposal, including the fact thatthey can be food-safe and ESD compatible, etc.
– Only flat belts can be individually sized and fabricated,
including the option of belt edge processing and theapplication of profiles etc.

➄➅

➀ Classical two-pulley drive➁ Multiple pulley drive➂ Mule drive➃ Taper-cone drive➄ Half twist drive➅ Multi spindle drive

29

Extremultus Compendium · 01/2019

2.9 Application groups
Siegling Extremultus
Power Transmission Belts
The material and structure of the tension member as wellas the coatings of the top face and underside determine
the characteristic profile of each flat belt. The Siegling
Extremultus range offers a wide variety of products forthe application groups, including different tension
members and coating variants:– Power Transmission Belts– Live Roller Belts– Tangential Belts– Drag Belts– Folder Gluer Belts– Machine Tapes– Elastic Food Tapes
The drive function is often mixed with sometimes
extremely demanding process tasks, particularly in the last
four groups. Siegling Extremultus flat belts boast versatile
belt properties, perfectly supporting these processes.

Siegling Extremultus Power Transmission Belts feature
impressively high efficiency (≥ 98 %), outstanding synchroni­
zation accuracy and easy handling.
They are also characterized by:– consistent and reliable speed and long service lives– short take-up lines, low creep– good damping capabilities– durability up to a capacity of 1850 kW– their ability to easily handle bevel and cone drives inwhich the belt rotates on its longitudinal axis
Typical coating combinations
LT = Leather underside, Fabric top face
LL = Leather underside and top face
GT = G elastomer underside, Fabric top face
GG = G elastomer underside and top face30

Extremultus Compendium · 01/2019

Siegling Extremultus
Live Roller Belts

Siegling Extremultus
Tangential Belts

Siegling Extremultus Live Roller Belts are energy-saving,durable drive components that ensure quick and reliable
distribution.

Siegling Extremultus Tangential Belts have been designed
to suit the wide range of yarn-manufacturing processes anddifferent drive shapes. They play a major role in ensuringconsistently high yarn quality and efficient production
thanks to the following characteristics:

They are also characterized by:– constant tension regardless of climate(aramide and polyester line)– superior abrasion-resistant coatings made of elastomer Gor polyurethane with constant friction coefficients andlong service lives– high flexibility and tensile strength– optimized surface textures for the spindle and motor side

– low power loss due to reduced flexing force– reduced belt slip and excellent levels of
power transmission– durable friction layers with constant grip

– short downtimes due to quick installation
Typical coating combinations
GG = G elastomer underside and top face
UU = Polyurethane underside and top face
RR = Medium Grip underside and top face

– energy-efficient polyester or aramide tension members– Highly orientated polyamide sheet tension memberswith good damping capabilities– low-noise and low-vibration operation– antistatic finishes
Typical coating combinations
GG = G elastomer underside and top face
UT = Polyurethane underside, Fabric top face

31

Extremultus Compendium · 01/2019

2.9 Application groups
Siegling Extremultus
Drag Belts

Siegling Extremultus
Folder Gluer Belts

Siegling Extremultus Drag Belts are special developmentswith superior mechanical and electrostatic characteristics
which make conveying and handling electronic compo­
nents more efficient and safe:

In the manufacture and processing of boxes and corru­gatedcardboard, Siegling Extremultus Folder Gluer Belts play a
key role in ensuring that the quality and productivity poten­
tial of the machinery is exploited to the full. The Extremultus
product range offers the right flat belt with specific charac­
teristics for each application:– thanks to the HC or HC+ properties (highly conductive
or highly conductive plus) the static charge that builds up
in the conveyor can be discharged in a more controlledmanner– due to simplified accumulation with TT types which
produce consistently low friction coefficients on the top
face and underside– due to a particularly high level of abrasion resistance,
as well as stable, fray free belt edges
Typical coating combinations
TT = Fabric underside and top face

32

Extremultus Compendium · 01/2019– thanks to tension-stable tension members made ofpolyester or aramide fabric, polyamide sheet or elastic
polyurethane– thanks to “custom grip” with a variety of surfaces thatare gentle on products – also approved for direct contact
with food– thanks to constant grip and long service life
Typical coating combinations
GG = G elastomer underside and top face
RR = Medium Grip underside and top faceSiegling Extremultus
Machine Tapes

Siegling Extremultus
Elastic Food Tapes

Siegling Extremultus machine tapes are vital components
of machinery in many industrial applications. Tension mem­bers made of polyester fabric, polyamide sheet or polyure­thane make them ideal for a range of different areas.
Siegling Extremultus machine tapes boast:

Siegling Extremultus elastic food tapes are specificallydesigned for applications in the food industry. The tension
member is made of elastic polyurethane and is thus 100%
fray free. Siegling Extremultus elastic food tapes are:– superior abrasion-resistant coatings with constant friction
coefficients and long service lives– available in blue or white to optimize quality assurance(contrast to food)– surface textures and coatings, as well as electrostatic
properties in keeping with requirements– elastic and thus excellent for short center distances,
belt scales and are suitable as spreading belts– damping capability tailored to requirements (dependingon the tension member)– easy to clean– low elongation at fitting, low shaft load
– suitable for small drum diameters/rolling knife edges
Different coating combinations, e. g.
GG = G elastomer underside and top face
TT = Fabric underside and top face
TG = Fabric underside and Elastomer G top face

33

Extremultus Compendium · 01/2019– food-safe; FDA and EU compliant– chemically resistant– available with High Grip coating
Select Siegling Extremultus elastic food tapes also support
the HACCP concept.
Typical coating combinations
UU = Polyurethane underside and top face
UR = Polyurethane underside, High Grip top face

34

Extremultus Compendium · 01/2019

3 	Chemical
Resistance
3.1 General information
3.2 Chemical resistance35

Extremultus Compendium · 01/2019

3.1 General information

Information regarding the resistance of Siegling Extremultus
coatings is based on laboratory testing and practicalexperience. It is valid in a standard climate (+23 °C/+73 °F and
50 % relative humidity).
In the event of significant deviations from the standard cli­mate, the resistance of the coatings may change. We recom­
mend you check the resistances yourself to account for
actual on-site conditions and the process media that affectthe belt. We can supply appropriate samples upon request.
Please contact us.
None of the Siegling Extremultus flat belts are resistant toorganic or inorganic acids.
Siegling Extremultus flat belts featuring G, N, P, T, U, R coat­ing materials are chemically impervious to oils and greases
as well as most commercially available solvents. However,keep them free of grease and oil to ensure smooth function­ing.
Siegling Extremultus flat belts with chrome leather (L) coat­ing material are impervious to machine oil, diesel fuel,petrol, benzene, common solvents including ethyl acetate,acetone, etc. and chlorinated hydrocarbons such as per­chloroethylene, etc.
Sub-types with leather coatings on one or both sides canbe used where oil and grease are a factor.
Note: The leather coating of Siegling Extremultus flat belts
should be treated regularly with Siegling Extremultus
Spraypaste, see Chapter 6.4.

36

Extremultus Compendium · 01/2019

The chemical resistance of Siegling Extremultus flat belts isof crucial significance, particularly in applications in which
the belts are in direct contact with food. This mainly
includes products featuring the coating materials U andHigh Grip R. In these applications it is also necessary to clean
the flat belts frequently.
Belts with Medium Grip R and G coatings are used in folder
gluer machines in the food industry.
The following tables list the chemical resistance of thesecoating materials compared to the most common substanc­es from the three following areas:– Pharmaceuticals, cosmetics– Cleaning agents, general– Food products
Detailed information about the chemical resistance of spe­cific products is available on request. We would be happy
to test our Siegling Extremultus flat belts to check their resis­
tance to your cleaning agent on request. Please contact
your local representative for more information:www.forbo.com/movement > Contact

3.2 Chemical ResistancePharmaceuticals, cosmetics
Aspirin
Castor oil
Hair shampoo*
Lanolin
Lysol
Mercury ointment
Nail polish*
Nail polish remover*
PerfumePine needle oil
QuinineSagrotan (disinfectant)
Soap (bars)
Soap (solution)
Spruce needle oil
Sulphur ointment*
Tincture of iodine
Toothpaste
Vaseline

Polyurethane U

High/Medium Grip R

G elastomer

●

●

●

●

–

❍

●

●

●

●

❍

●

–
–

●

●

●

●

❍

●

–

●

●

–
–
–

❍

●

●

●

●

–

–

●

●

●

❍

●

❍

●

❍

●

–
–

●

❍

❍

●

❍

–

❍

●

●

●

●

–

●

Polyurethane U

High/Medium Grip R

G elastomer

–
–

❍

●

●

●

❍

❍

❍

–

●

–

❍

●

●

–
–

●

●

–

❍

●

–
–

●

–

●

●

●

●

–
–

●

–
–

●

●

●

❍

❍

❍

–

–
–
–
–
–
–

●

❍

●

●

●

●

●

–
–

–
–

●

●

●

●

●

●

●

Cleaning agents, general
Acids, concentrated (strong)
Acids, diluted (weak)
Alcohols
Aldehydes
Aliphatic hydrocarbons
AminesAromatic hydrocarbons
Chlorinated hydrocarbons
Crude oil/mineral oil
Ester
Ether
Fats, oils
Fuels
Halogens, dry
Hydrofluoric acid
KetonesLyes, concentrated (strong)Lyes, diluted (weak)
Organic acids
Oxidizing acids
Solutions of inorganic salts
Turpentine
Unsaturated chlorinated hydrocarbons
Water, cold
Water, warm

37

Extremultus Compendium · 01/2019

–

–

●

❍

●

●

●

❍

–

3.2 Chemical ResistanceFood products
Polyurethane U
Apple juice
Apple sauce
Beef tallow
Beer
Blancmange
BrandyBread
ButterButtermilk
Cabbage, pickled
Cake*
CheeseCinnamon, powder
Cinnamon, sticks
Citric acid
Cloves
Cocoa powder
Cocoa, ready to drink
Coconut oil
Cod liver oil
Coffee (beans or ground)
Coffee (ready to drink)Cola concentrates
Cooking oil, animal
Cooking oil, vegetable
Corn oilCorn (maize)
Cream, whipped cream
Curd cheese
Dairy products
Dextrose
Eggs (raw, boiled)
Fish
Fish (pickled in various sauces)*
Flour
Fruit juices
Fruit salad (fat-free)Gelatine
Gin
Grain
Grapefruit juice
GrapesGravy
Honey
Horseradish, ready to serve
Jam
Jelly
Lemon flavouring
Lemon juice
Lemon peel
Linseed oil

38

Extremultus Compendium · 01/2019

High/Medium Grip R

G elastomer

●

●

●

●

●

●

●

–

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

–

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

❍

●

–
–

●

●

●

●

●

●

●

●

●

●

●

●

●

–
–
–

●

●

●

●

❍

●

●

❍

●

●

●

●

●

●

●

●

●
●

●

●

●

●

●

●

❍

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

–

●

Liqueurs
Margarine
Mayonnaise
Meat
Milk
Molasses
Mustard
Olive oilOrange juice
Palm oil
Paprika
Peanut oil
PepperPineapple juice
Pork dripping
Potato purée
Potato salad
Rice
Rum*
Salt herring
Salt, dry
Saltwater
Sausage
Semolina
Soda water
Soft drinks
Soyabean oil
Starch solution, starch (aqueous)
Starch syrup
Sugar beet syrup
Sugar, dry
Sugar, solution
Sunflower oil
Tartaric acid
Tea, brewed
Tea leaves
Tomato juice
Tomato ketchup
Tomatoes
Vanilla
Vegetables, cooked
Vegetables, raw
Vinegar 5 %Vinegar essence
Water
WhiskyWine, mulled wine
Yeast

● = Good resistance39lPolyurethane U

High/Medium Grip R

G elastomer

●

●

●

●

●

●

–
–

●

●

●

●

●

●

●

●

●

●

❍

●

●

–

●

●

●

●

●

–

●

●

●

●

●

–

●

●

●

●
●

●

●

●

–

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–

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–

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❍

●

❍

–

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–

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❍ = Limited resistance l – = No resistance

Extremultus Compendium · 01/2019●l* Belt’s resistance depends on chemical composition

40

Extremultus Compendium · 01/2019

4 	Belt selection

4.1 General information
4.2 Tension member
4.3 Coating materials
4.4 Extremultus Product Finder
4.5 B_Rex Calculator

41

Extremultus Compendium · 01/2019

4.1 General information

Siegling Extremultus products are available in a variety ofdifferent material combinations.
The properties of the tension member and of the coating
material are crucial when it comes to selecting the right,
application-specific Siegling Extremultus product. The
properties required depend on the overall context of use.
To ensure proper belt selection, all of the parametersmust be thoroughly determined.

Due to technical limitations in production as well as material
and application-specific properties, not all material com­binations are possible or sensible. Do not hesitate to get intouch with your local representative should you have any
questions regarding the selection of Siegling Extremultus
products for a specific application:www.forbo.com/movement > Contact
We will be delighted to help.

The basic procedure when selecting a belt is
usually as follows:– Gather together all conditions of use– Determine the tension member series and version– Determine the coating materials– Sizing

Tension member properties
Max. elongation at fitting
The maximum elongation at fitting is the maximum elongation with which a belt in this tension member series can be
fitted in this application and still undergo no permanent
damage due to excessive strand forces.

Effective pull transmission
The effective pull transmission refers to the ability of thetension member series to transmit a high effective pull.
The greater the (effective) pull transmitted per surface unit,
the better the transmission capacity.

Initial value of the shaft load
The initial value of the shaft load adjusts with a brand new,
non-relaxed belt and is sometimes significantly higher thanthe calculated shaft load (in a steady state). The ratio
between the initial value and the steady value of the shaft
load is a function of the tension member material. Moreinformation on this topic is given in Chapter 6.3.

Climate resistance
Climate resistance indicates whether and to what degree
the respective tension member material is affected byclimatic changes (temperature and humidity).

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Extremultus Compendium · 01/2019

Damping
Damping is a measurement of how well the belt and tension member can absorb and break down mechanical influences such as peaks in power and vibrations. Damping isthus directly proportional to the E-modulus of the material.

4.2 Tension member

Polyester line*

Aramide line*

high max.
elongation at fittinghigh max.
elongation at fittinghigh initialvalue of the
shaft load

highdampingGood resistance toclimatic conditions

high effective pulltransmission

Polyamide line*

high initialvalue of the
shaft load

highdamping

Polyurethane line

high max.
elongation at fitting

highdampingGood resistance toclimatic conditions

high max.
elongation at fittinghigh initialvalue of the
shaft loadhigh effective pulltransmission

highdampingGood resistance toclimatic conditions* The material-specific properties shown apply to fabric tension members as well as sheets and endless cord.

43high effective pulltransmission

Good resistance toclimatic conditions

Extremultus Compendium · 01/2019high initialvalue of the
shaft loadhigh effective pulltransmission

4.3 Coating materials
Coating material properties
Abrasion resistanceAbrasion resistance refers to contact with the usual materials
in the corresponding applications.

Transport capacity
Transport capacity is derived from the friction coefficients
between the coating materials and a steel plate. The friction
coefficients are measured as part of Forbo Movement
Systems’ internal, standardized tests.

G elastomer

Operating noise
The operating noise depends on the surface pattern andthe hardness of the coating material. The conveyor design
also plays a significant role here.

Temperature stability
Temperature stability is the temperature range in which thematerials or belts can be operated without the materials
undergoing irreversible thermal disintegration as a result ofhigh temperatures or damage as a result of brittleness at
low temperatures.

High/Medium Grip R

Good abrasion
resistanceHightemperaturestability

Good grip

Low operating
noise

44

Good abrasion
resistance

Extremultus Compendium · 01/2019

High
temperaturestability

Good grip

Low operatingnoiseFabric T

Chrome leather L

Good abrasion
resistanceHightemperaturestability

Good abrasion
resistanceGood grip

Hightemperaturestability

Low operatingnoise

Low operatingnoise

Nonwoven polyester N

Polyurethane U

Good abrasion
resistanceHightemperaturestability

45

Good abrasion
resistanceGood grip

Low operating
noise

Extremultus Compendium · 01/2019

Good grip

Hightemperaturestability

Good grip

Low operatingnoise4.4 Extremultus Product Finder

The Extremultus Product Finder provides a pragmatic
option for selecting belts. This convenient finder is available
as an e-tool on the Forbo Movement Systems homepage
and is optimized for both computers and mobile devices.
www.forbo.com/movement > E-Tools
The Extremultus Product Finder is a search engine used
to search for, filter and ultimately display all of the Siegling
Extremultus products based on their technical data, signi­
ficant parameters and specific properties. It is also possible
to filter according to application group and text retrieval.

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Extremultus Compendium · 01/2019

A successful search or filtering process displays a list of
results. The article number, type designation and data
sheets (see Chapter 2.5) in PDF format are then available forall of the products in the results list. Inquiry can be placed
directly.

4.5 B_Rex Calculator

Forbo Movement Systems has been designing customer
applications with its in-house calculator B_Rex for years. You
receive the calculator free of charge upon registration at:www.forbo.com/movement > E-Tools
B_Rex makes it possible to simulate the reproduction andchanging of conveyors and drives on the PC, simulating the
combination of any system with any Siegling Extremultus
flat belt. The product data is included with the program in
the form of a database.
As a general rule, designing with B_Rex is divided into four
easy steps. All the designer is required to do is input infor­
mation that s/he already knows. Any parameter changes inthe design result immediately in a new calculation, making
the system very easy to optimize. B_Rex is freely available
and is currently the most advanced calculator with the mostpossibilities in the field of light materials handling. The pro­gram also contains instructions in PDF format.
The B_Rex calculator is a convenient option for calculating
and visualizing the development of belt force and elonga­tion at fitting for any belt configuration. Typical elements
in materials handling such as live rollers, skid plates etc.
can be modeled quickly using configurable components.

47

Extremultus Compendium · 01/2019

For classic roller conveyors with rear or head drives, prefabri­cated models are available to support frequent systemmodelling. There is also a separate calculation model avail­able for the classic 2-pulley power transmission drive. In
addition, a vibration analysis is carried out for each belt seg­
ment. This analysis issues a warning prior to any transversal
vibrations (“flapping”) of the flat belt, something that canconsiderably shorten the lifetime of the belt.
Each version of the program has a time limit for our custom­ers. This is to ensure that the current version is downloadedat regular intervals so that customers remain up-to-date at
all times when it comes to bug fixes and our current prod­
uct range.
We hope you enjoy working with this program. Please direct
any questions or problems to: brex@forbo.com

48

Extremultus Compendium · 01/20195 	Manufacturingdata
5.1 Manufacturing tolerances
5.2 Delivery dimensions

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Extremultus Compendium · 01/2019

5.1 Manufacturing tolerances

As a general rule the manufacturing tolerances indicated in the following tables apply. They do not include any
geometric changes that may occur following manufacture as a result of climatic fluctuations or other external
influences. In some cases, special tolerances are also possible upon request. Please contact your local representative:
www.forbo.com/movement > Contact

Length tolerances

Width tolerances

Polyester line and Aramide line (fabric)

Polyester line and Aramide line (fabric)

300 – 5000 mm± 0.30 %10 – 120 mm+ 0.2/– 0.3 mm

5001 – 15000 mm± 0.20 %121 – 500 mm± 1.5 mm

> 15000 mm± 0.15 %> 500 mm

± 5.0 mmPolyester line and Aramide line (cord)

Polyester line and Aramide line (cord)

500 – 1000 mm± 0.50 %20 – 50 mm± 1.0 mm1001 – 5000 mm± 0.40 %51 – 100 mm± 1.5 mm

> 5000 mm± 0.30 %101 – 250 mm± 2.0 mm

> 250 mm

± 3.0 mmPolyamide line (sheet and fabric)
300 – 5000 mm± 0.50 %Polyamide line (sheet and fabric)

5001 – 15000 mm± 0.30 %10 – 50 mm± 1.0 mm

> 15000 mm± 0.20 %51 – 120 mm± 2.0 mm

121 – 500 mm± 3.0 mm

501 – 1000 mm± 10.0 mm

Polyurethane line
300 – 5000 mm± 0.30 %

5001 – 15000 mm± 0.20 %Polyurethane line

> 15000 mm± 0.15 %10 – 120 mm+ 0.2/– 0.3 mm

121 – 500 mm± 1.5 mm

> 500 mm

± 5.0 mmThickness tolerances
Siegling Extremultus flat belts can have different
thickness tolerances depending on the combinationof tension member and coating material. Please always
observe the information on the respective data sheets.

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Extremultus Compendium · 01/2019

Tolerances for perforations
All lines
Diameter of hole

± 0.5 mm

Spacing between holes± 1.0 mm

5.2 Delivery dimensions

Siegling Extremultus products are produced in large widths and extremely long lengths of roll material.
The products can then be delivered in different, customer-specific ways, depending on production or standard
delivery dimensions.

Available as

How to measure order length

All Siegling Extremultus flat belts,
except for those with tension members
made of truly endless cord, can bedelivered in the following three forms:

When ordering flat belts spliced endless, the length is measured inside, i.e. on
the underside.

– Open, as roll material– Prepared for on-site installation in
the following variants– cut at 90° or 60° angles– prepared for being made endlesson one side
– prepared for being made endlesson both sides– Endless, spliced and ready to install(even flat belts with tension mem­bers made of endless cord)

To do this, place the flat belt on its edge, affix a steel tape firmly on its inside(Fig. 1) or measure directly over the pulleys (Fig. 2).
If your machinery has a take-up unit, it should be adjusted to determine theorder length as shown in figure 3.
The order length should be determined when the take-up unit is in the zero
position. We recommend selecting a zero position for the take-up unit thatenables a take-up line greater than the path required to apply the elongation at
fitting. In addition, it should be possible to have a return distance from the zero
position that is greater than the minus tolerance when manufacturing the belt.

Please contact your local representa­
tive for more information about thedelivery forms available:
www.forbo.com/movement >Contact
We will be delighted to help.

1

2

Return distanceTake-up line > εZero position

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Extremultus Compendium · 01/2019

3

52

Extremultus Compendium · 01/20196 	Handling
flat belts
6.1 Storage
6.2 Condition of machinery
6.3 Fitting and tensioning
6.4 Maintenance and handling

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Extremultus Compendium · 01/2019

6.1 Storage

Due to the specific properties of the Siegling Extremultus
flat belts, there are a few things to consider when it comesto storage conditions:➀➁– The belts should be stored under normal ambientconditions climate (23 °C/+73 °F, 50 % humidity) as per
DIN EN ISO 291– Do not lay the material on the belt edge. Instead, hang it
up on a pipe or similar (Fig. 1) or, if there is no otheroption, store in an upright position (Fig. 2).
– Upon consultation, high-quality flat belts (e. g: tangential
belts) with polyamide tension members are sent from ourfactory in special air-tight bags. Do not open the bags
until the belts are ready to be fitted– Do not expose flat belts to direct sunlight (take special
care with G, R and U coatings)
The material – especially the polyamide line – can deformslightly if exposed to humidity or heat on one side. But thisdeformation will disappear once elongated by 0.2 to 0.4 %,guaranteeing smooth running. Moisture greatly affects
Siegling Extremultus flat belts with polyamide tension
members. The E-modulus, and with it the important proper­

54

Extremultus Compendium · 01/2019

ties of the flat belt, can undergo significant change whenused in a moist environment or on contact with water.
If you are using flat belts with this tension member inextreme ambient conditions, we recommend you contact
Forbo Movement Systems application support.

6.2 Condition of machinery

The condition of the machinery operating the flat belts is
an important factor when it comes to maximizing the ser­vice life of the Siegling Extremultus flat belts. The maximum
service life of the flat belts and their smooth operation can
only be guaranteed if the machinery is in faultless condition.
The following list contains points that, if not followed, willlead to the premature failure of the flat belt:– Clean any anti-corrosion agents, dirt and oil fromthe pulley faces– Check parallelism of shafts and align pulleys, adjusting inaccordance with manufacturer’s instructions as needed– Check and ensure that all drum and support rolls are
running smoothly

55

Extremultus Compendium · 01/2019– Eliminate any possibility of the flat belt running up during
operation. This includes using pulleys without flanges (seealso Chapter 8) as well as checking the distances between
the frame or housing of the machinery and the flat belts
and adjusting if necessary.
– Ensure that the machinery and its surroundings are clean.
Dirt/deposits on the underside of the flat belt can lead toexcessive mechanical load and/or excessive slip, destroy­
ing the flat belt.
Note: Further information to improve the lifetime of Siegling
Extremultus Flat belts as well as information to fix flaws andcauses of failures, you will find in Chapter 11.

6.3 Fitting and tensioning
Fitting
Improper handling when fitting the Siegling Extremultus
flat belts poses the risk of damaging the belts to such an
extent that the fatigue strength of the flat belts in operation
can no longer be guaranteed. For this reason only qualified
professionals should fit and tension the belts if at all possible.
We would be delighted to set up an appointment to install
the flat belts on-site.
www.forbo.com/movement > Contact
Always observe the instructions specified by the machine
manufacturer when fitting the Siegling Extremultus flat
belts. Never wind Siegling Extremultus belts over pulleyedges or use accessories which cause damage to the flat
belt edges and result in bends or tears in the belt.

aFlat belts in the aramide line are particularly susceptible tothis type of damage (due to the aramide tension member).
Most machines have a clamping device to decrease thecenter distance between the pulleys in order to fit the flat
belts. If this is not the case or if the take-up of the clamping
device is not large enough, size the flat belt so that therequired tension is reached upon fitting.

➀➁

Possible tools include:– mounting cone (a)– chain hoist (b – use only with polyamide line)➂b➃b:➀ Clamps➁ Chain hoist➂ Protective layer (piece of belt)➃ Belt width (approx.)

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Extremultus Compendium · 01/2019

In addition to the methods used to fit the flat belts, thedirection of the belt in relation to the wedge splice mustalso be taken into account for flat belts with polyamide
tension members.
The cross-section view of the wedge splice shows that thissplice type has a front edge which, depending on how theflat belt is aligned in relation to the direction, is either on the
top face or the underside of the flat belt.
Circulation on the pulleys will be smooth and the splicing
area will have non-critical contact with the conveyed goods
when the front edge is on the opposite side of the criticalcontact point (pulley or conveyed goods).
The critical contact point depends on the use of the Siegling
Extremultus flat belt.

Front edge on the top face

Front edge at underside

Direction of movement

Direction of movement

Front edge

Front edge

1

If, for example, the flat belt is used as a power transmission
belt in a 2-pulley drive, contact with the pulley is seen as thecritical contact point because the pulley is generally the
only contact with the flat belt. To guarantee improved dura­
bility for the wedge splice, it is a good idea to align it asshown in Figure 1.

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Extremultus Compendium · 01/2019

2

If, however, the flat belt is used to transport an abrasive
product such as paper, the critical contact point is between
the flat belt and the conveyed goods. Contact with the pul­
ley then usually plays a minor role. We recommend align­
ment as shown in figure 2.

6.3 Fitting and tensioning
Tensioning
Flat belts must be pre-tensioned in order to transmit a given
torque without slippage. This tension is usually applied
using the machine’s tensioning device. Thereby, the flat belt
will be stretched and this leads to an elongation comparedto the non-tensioned initial state. This so called elongationof fitting is given in percent and results from detailed calculation and dimensioning of the Siegling Extremultus flat belt
for a specific application.
The basic standard values for the elongation at fitting of thedifferent tension members regarding different applications
are specified in the shown table.

Productline

Aramideline

Polyesterline

A variety of different methods and tools can be used totension and elongate the Siegling Extremultus flat belts.

Tension design

Application Group/
Function

Recommended
Elongation
at fitting [%]FabricPower Transmission Belts
Tangential Belts
Live Roller Belts

0.3 – 1.0
0.3 – 0.8
0.2 – 0.5

Cord (truly endlless) Power Transmission Belts

0.3 – 1.0

FabricPower Transmission Belts
Tangential Belts
Folder Gluer Belts*,
Drag Belts,
Maschine Tapes*
Live Roller Belts*

1.0 – 2.0/2.5**
1.5 – 2.0/2.5**
0.3 – 2.0

Cord
(truly endlless)Power Transmission Belts,
Maschine Tapes*

0.5 – 1.5

FabricPolyamide
line
Sheet

Polyurethane line

Foil

0.8 – 1.5

Maschine Tapes*

0.6 – 3.0

Power Transmission Belts,
Live Roller Belts
Tangential Belts
Rotor Belts
Folder Gluer Belts*,
Drag Belts

1.5 – 3.0

Maschine Tapes*

1.8 – 2.8
2.5 – 3.5
1.5 – 3.0
3.0 – 8.0

* Tension just enough so they operate properly**	Max. Elongation at fitting 2.5 % possible for GG 40E-32 NSTR/NSTR
grey/black (822128) and GG 40E-37 NSTR/NSTR black (822129)

Measuring marks
With the belt placed flat, apply two thin measuring marks at
a defined distance, e.g. 1000 mm, on the top face of the flat
belt. After fitting, use the take-up unit to elongate the flat
belt lengthways until the distance between the measuringmarks reaches the calculated value (see sample calculationin the table below).
It makes sense to turn the drive several times after following
the first elongation and then check the elongation value
and correct if necessary. Only by turning can the elongation
be distributed along the entire length of the belt.
Note: Do not measure above the splice area!

Example: Distance between measuring marks fora required 2 % belt elongation.
not elongatedelongated

1000 mm1020 mm

500 mm

510 mm

250 mm

255 mm58

Extremultus Compendium · 01/2019

Elongation gauge
A special service offered by Forbo Movement Systems involves apply­
ing reference measuring marks to the Siegling Extremultus flat belt
when ordered (see Chapter 7.4). After elongating, check the elongation
value using the elongation gauge after several turns.

Mechanical elongation measuring device
Use one of Forbo Movement Systems’ mechanical elongation measur­ing devices to directly measure the elongation at fitting. Clamp thedevice to the belt edge and set the scale to zero. The elongation value
can be read continuously during elongation.
Remove the device prior to turning the drive. It is only possible tocheck later on if the edges of the belt clamps were precisely marked
prior to removing.

Electronic vibration meter
A commercially available electronic vibration meter (accuracy< 1/10 Hz) can be used to indirectly determine the belt tension via
the vibration behaviour of the belt strand. The frequency demonstrat­
ed by the flat belt at a defined elongation must be calculated prior
to the measuring process.
A mechanical strike, manually striking with a hammer for example,
makes the belt strand vibrate and its frequency is measured. The flat
belt is stretched until the calculated vibration frequency is reached.
Check the elongation by turning the drive several times and measur­ing the frequency again.
Take the running-in behavior (relaxation) of the tension member into
account when fitting brand new flat belts for the first time. Moredetailed information can be found in the following section “Runningin behavior of plastic tension members”. Depending on the tension
member, set the frequencies at the beginning slightly higher thanthose calculated for run-in operation.
Note: Correctly calculating the frequency of the belt strand and reliably
measuring the vibration of the Siegling Extremultus flat belt using theelectronic vibration meter both require a high degree of technicalknowledge and experience. Please contact Forbo Movement Systems
to properly tension according to this method.

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Extremultus Compendium · 01/2019

6.3 Fitting and tensioning
Running-in behavior of plastic tension members
Plastics exhibit running-in behavior, also known as relaxation, under dynamic loads. In the case of flat belts with plastic
tension members, this behavior presents in the form of a high shaft load when fitting the belt for the first time.

cinitial =FW initial
FW dPermissible maximum shaft load (depending on machinery)

Shaft load FW [N]Constant elongation
When fitting new Siegling Extremultus flat belts
with a defined elongation, there is a high initialshaft load value FW initial. Over the course of theinitial operating hours, this shaft load falls to asteady value FW steady that corresponds to the cal­culated dynamic shaft load FWd. The graph to theright illustrates the sample development of a
Siegling Extremultus flat belt during the runningin phase.

Initialvalue

Steady state
value
recommended
idle speed range

0
Number of bending cycles

The ratio cinitial varies between the initial shaft
load value and the steady value depending on
the material and design of the tension member.
In addition to various other factors, this ratio
determines the duration of the running-in pro­
cess and is thus extremely difficult to predict. As ageneral rule, at least 150,000 bending cycles (cor­responding to 75,000 revolutions in a 2-pulley
drive) should be applied to Siegling Extremultus
flat belts before operating the machinery at full
load.

Note: The steady state value of the shaft load is the basis for calculating thepower transmission of a flat belt. The higher initial shaft load value should
be taken into account by the designer, at least when dimensioning the shaft
bearings based on static loads.

Line

Tension member design

Running-in ratio cinitial

Fabric

1.8

Cord

1.5

Polyester line
Aramide line
Polyamide line

1.4

Cord

1.5

Sheet

2.2

Steady state
value

Elongation at fitting ε [%]Constant pre-tension force
Pneumatic, spring or weight-loaded take-up units
must tension the flat belts using at least the cal­culated dynamic shaft load FWd. The appro­priate
elongation at fitting ε is only reached after a cer­tain running-in
period due to the running-in behavior of thetension members. The center distance increases
slightly during the running-in period.

FabricInitialvalue

recommended
idle speed range

0
Number of bending cycles

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Extremultus Compendium · 01/2019

Installing strong flat belts
When installing Siegling Extremultus flat belts with a high width-related shaft load F’W, forces that are significantly higher
than the calculated force values may be applied to the shafts and bearings during the initial fitting.

First stage:
Tension the Siegling Extremultus flat
belt only to about 50 % (in individual
cases up to max. 70 %) of the required
elonga­tion at fitting (ε50 % = 0.5 · ε). The
machinery should then be operated
with low load at moder­ate speed. Afterapproximately 150,000 bending cycles(corresponding to 75,000 revolutions in
a 2-pulley drive) there should be no
more significant changes in the shaft
load (in some cases this point canoccur earlier or somewhat later).

Initial valueat ε 100 %Shaft load FW [N]Tensioning in two stages
Installing Siegling Extremultus
flat belts with a high width-related
shaft load can be problematic forbearing machine parts. The running-in
be­­havior of the plastic tension mem­ber can cause the permissible loadon the shafts and/or bearings of themachinery to be exceeded by thehigh initial value of the shaft load,causing damage to the machinery.
In such cases, Forbo Movement
Systems recommends following
a two-stage tensioning method:at ε 50 %Permissible maximum shaft load (depending on machinery)at ε 100 %constant

Steady state
value

recommended
idle speed range

0
Number of bending cycles

Second stage:
Now tension the Siegling Extremultus
flat belt to the required elongation at
fitting (ε100% = ε) and run it in foranother approx. 50,000 bending cycles(corresponding to 25,000 revolutions in
a 2-pulley drive). The machinery canthen be run safely in the full load
range.
The flat belt will continue running induring operation until it reaches thesteady state value of the shaft load. No
further action is necessary.

By using this two-stage tensioning
method, it is possible to avoid exceed­
ing the permissible maximum value ofthe shaft load (FW,max) for the machin­ery (shown in light grey in the graphic
above). The two-stage tensioning
method has no negative affect on thewidth-based shaft load F’W of the
Siegling Extremultus flat belt or on the
maximum possible power transmission
by the flat belt.
Note: Forbo Movement Systems strongly
advises you against tensioning the flat
belts in more than two stages, otherwise
the shaft load-elongation behavior in thetension members can change, rendering
the flat belt useless (dead tensioning theflat belt).

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6.3 Fitting and tensioning
Removing and re-fitting used flat belts
When a used flat belt is removed, it must have the sameelongation as before when it is re-fitted and put back into
operation.
We therefore recommend applying clear measuring marks
to the flat belt or marking the position of the take-up unit
before loosening the belt and removing it. When re-fitting
the flat belt, you must restore the original measurement
markings and the original position of the take-up unit.

When using an electronic vibration meter, determine thefrequency of the belt strand in its original state of tension
prior to loosening and set it again when re-fitting the belt.
Due to measuring uncertainties, however, we recommend
using measuring marks when tensioning the Siegling
Extremultus flat belts during re-fitting.
Sufficiently relaxed flat belts generally do not display
running-in behavior again when re-fitted.
Note: A minimum window of time (>24 h) must be observed
between removing and re-fitting the Siegling Extremultus flat
belts so that the flat belts have time to slacken

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Extremultus Compendium · 01/2019

6.4 Maintenance and handling

MaintenanceIn general, most Siegling Extremultus flat belts are mainte­
nance-free.

Maintenance of Siegling Extremultus leather surfaces
In the absence of regular care (or if care is excessive), thechrome leather layer loses its special properties. It should
therefore be checked every two to three weeks.
When checking, the leather surface should be soft, greasy
and matt. If the film of grease has noticeably worn down
since last checked, applying Siegling Extremultus spray
paste (item no. 880026) to the surface of the belt is recom­
mended. If the surface of the leather is already hard, shiny
and dry or is very soiled, use a soft wire brush to roughen it
up beforehand. The pulleys should also be regularly cleaned
during this service time. You should contact Forbo
Movement Systems immediately if there is a noticeablechange in the appearance of the belt, if unusual noises
develop, or if there is excessive abrasion (e.g. red dust).
www.forbo.com/movement > Contact

Cleanliness around the machinery and the operatingcon­dition of the machinery can also play a role andshould be checked at regular intervals.
Further information about this topic, you will find in
Chapter 11.

Permissible operating temperatures
Forbo Movement Systems recommends that you adhere to
the following guidelines to ensure the long-term operationof Siegling Extremultus flat belts:
The power elongation values of the tension members
and the minimal drum diameter are within the limits of
the operating temperatures indicated in the productdata sheets as part of normal product tolerances. While itis possible to use them in colder temperatures, such asin refrigerated warehouses, they would require a larger
roll diameter, specific friction coatings and laboratory
trials conducted at Forbo Movement Systems.

Note: Use only Siegling Extremultus spray paste for the chromeleather surfaces of the Siegling Extremultus flat belts!

Note: Please adhere to the information contained in the
Siegling Extremultus data sheets regarding permissible
operating temperatures. They may differ from the values
indicated in the table on a case-by-case basis

Product line

Tension member design

Coatings

Permissible operating [°C]FabricAll-20/+70

Cord

All-20/+60

FabricAll-20/+70

Cord

All-20/+60

FabricAll-20/+80Sheet

LL, LT and uncoated-40/+80

Sheet

All other coatings(GG, GT, TT, TG, RR, UU, NN)-20/+80

Foil

All-20/+60

Aramide line
Polyester line

Polyamide line

Polyurethane line

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64

Extremultus Compendium · 01/20197 	Splicing andfabrication
technology
7.1

General information

7.2 Splice types
7.3 Splicing
7.4 Fabrication options

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7.1 General information

Precise endless splicing is a crucial prerequisite for all
Siegling Extremultus flat belts manufactured as rolledmaterial to ensure good tracking properties and a longservice life.

Depending on the application and the customer’s request,
endless splices can be fabricated directly on-site within themachinery. Alternatively, we can take care of the endlesssplicing in one of our fabrication centers and then deliver
the endlessly spliced Siegling Extremultus flat belts to you.

Except for when using mechanical fasteners, the types ofsplicing are distinguished by the geometric shape of theends of the flat belts, e.g. wedge splice, Z-splice and butt
splice. Depending on the tension member material used,
the prepared ends of the flat belt are either glued or melted
together. However, melting the tension member materials
together requires thermoplastic materials such as aramide,
polyester and polyurethane.

In addition to creating endless splices, our fabrication
centers can also take care of perforations, profiles andbelt edge processing for the Siegling Extremultus flat belts
on request. As with splicing technology, it is necessary tocheck on a case-by-case basis whether the additional
processing requested is technically feasible and approved
by Forbo Movement Systems.

Forbo Movement Systems keeps procedures andequipment technology in tune with current flat belt
developments by co-operating closely with users andequipment manufacturers, offering compatible fabrica­tion systems to provide effective and reliable endlesssplicing.

The following descriptions illustrate the basic nature of
the various types of splices and their manufacture. If you
require work instructions to create an endless splice for a
specific Siegling Extremultus flat belt, please contact yourlocal representative at Forbo Movement Systems:
www.forbo.com/movement > Contact– high-quality tools with all the accessories

We will be delighted to help.

– detailed instruction manuals– comprehensive service

Furthermore you will find more information at:www.forbo.com/movement > Products > Splicing Tools

Preparation and splicing methods
PreparationP

Splicing

S

CuttingPC

Bonding (≤120 °C)

SB

Splitting/Peeling

PS

Melting (>120 °C)

SM

Grinding

PG

Clamping

SC

Punch-cutting

PP

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7.2 Splice types

Wedge spliceZ-splice

The wedge splice is a splice in which the ends of the cut flat
belt are ground in the shape of a wedge. To join the groundends of the flat belt, place the ends over one another, apply
glue and place the ends in a heating device.

To produce a Z-splice, an appropriate punching machinepunches the ends of the cut flat belt in the shape of a Z.
The punched ends then slide together and are joined using
a heating device.

A bonding process is used for this splice, which, in turn,is used for Siegling Extremultus flat belts in the polyamideline. The flat belts are generally cut and ground at 90 ° or
60 ° angles. The splicing length can be varied based on
the incline of the wedge:

As this is a melt splice it is only permitted for thermoplastic
materials (polyester, aramide and polyurethane lines as well
as some products from the polyamide line with fabric ten­sion members (only with U foil)). The Z-splices for Siegling
Extremultus flat belts are available in four different subtypes that differ in the length and/or width of theZ- edges:– 3.5 mm : 100 mm– 4.5 mm : 100 mm
Preparation– Wedge-shaped grinding of the belt ends using theappropriate preparation tools
Bonded endless splicing– Align and clamp the prepared belt ends, remove thehold-down bar with the clamped end of the splice– Apply adhesive(s) to the splicing areain accordance with the belt structure and the splicing
data sheet– Replace the hold-down bar with the clamped end of
the splice, insert the shim bars
– Glue/heat the splice (≤ 120°C) and apply pressure witha defined holding time
Note: Depending on the surface pattern of the belt, structuralmesh, levelling mats etc. must be inserted above or below the
belt (see splicing data sheet).
67

Extremultus Compendium · 01/2019– 35 x 5.75 mm– 35 x 11.5 mm– 70 x 11.5 mm– 110 x 11.5 mm

Preparation– Z-shaped punching of the belt ends with hand punchesor punching devices
Melting process for endless splicing– Insert texture foil into the splice guide (replicates texture
and allows outgassing of plastics)– Insert belt ends (including U foil if necessary) precisely
into the splice guide– Fit texture foil to the splicing area (replicates texture andallows for outgassing of plastics)– Insert the splice guide into a heating device, melt using
heat (> 120 °C) and pressure with a defined holding time7.2 Splice types

Butt splice

Overlap splice

In the case of butt splices, the ends of the flat belt must firstbe perfectly aligned at a 90° angle and cut straight tolength. The ends are then melted and pressed into one
another.
Forbo Movement Systems also produces butt splices withdifferent angles for special applications.

When executing an overlap splice, the ends of the flat belt
must first be at exactly a 90° angle and cut exactly to length.
The ends are then laid on top of one another with approxi­
mately 2 mm of overlap and then joined in a heating device.
Forbo Movement Systems also produces overlap splices
with other angles for special applications.

A melting process is always used to create butt splices. Dueto the minimal splicing surface between the ends of the flat
belt, this type of splice is only suitable for applications inwhich relatively minimal forces act on the flat belt. Hencebutt splices are only used to join Siegling Extremultus flat
belts of the polyurethane line.

A melting process is always used to create an overlap splice.
Although the splicing surface is larger than that of a butt
splice, it is still extremely small compared to a wedge orZ-splice. For this reason the overlap splice, like the butt
splice, is also only suitable for Siegling Extremultus flat belts
in the polyurethane line.

Preparation

Preparation– Cut belt ends parallel– Cut belt ends parallel

Melting process for endless splicing

Melting process for endless splicing– Position the ends of the flat belt on opposite sides of
the heating plate– Insert texture foil into a splice guide (replicates texture
and allows outgassing of plastics)– Melt the ends of the flat belt together– Insert belt ends precisely into the splice guide– Remove the heating plate and press the ends together– Fit texture foil to the splicing area (replicates texture andallows for outgassing of plastics)– Insert the splice guide into a heating device, melt using
heat (> 120 °C) and pressure with a defined holding time

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Mechanical fasteners
Mechanical fasteners are wire clamps or hinge designs thatare pressed into the ends of the Siegling Extremultus flat
belts and then held together with a connecting wire or pin.
Mechanical fasteners are generally available in metal andplastic.
This type of splicing was developed at the start of industrial­
ization and was the only viable option to adequately join
flat belts at the time. Nowadays, mechanical fasteners havebecome much more delicate due to the high-strength
materials. In addition, the splicing techniques describedabove represent other options for joining flat belts that havebeen added over time. That is why, if at all possible, mechan­ical fasteners are only used for Siegling Extremultus flat belts
as a special solution and only if expressly requested.
Preparation– Cut belt ends vertically at 90° angle– Affix the fasteners to the belt ends
Endless splicing with mechanical fasteners– Place the belt ends together so that the eyes ofthe fasteners are aligned in a row– Guide the connecting wire/pin through the eyesof the fasteners

69

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7.3 Splicing

Splices in flat belts are largely created by hand. Only individual steps
can be automated. That is why errors can easily occur when creating
splices. These errors can be avoided by following the proceduredescribed below.

1
Splicing instructions
2

Adjusting, affixing, ends of– Place the prepared ends of the belt in the middle of the splice guide. Push the Z-fingers on theends of the splice tightly together.

the splice in the splice guideZ-splice 407_00– Check which distance between the ends of the splice has to be adhered to.
Distance >> see splice data sheet

Splicing procedure

Melt splice

Type of splice (AdV)

Z-splice (09)a) At a distance 5of 0Preparing
mm: Affix theof the belt with clamps
onto thespliceguide.clamp and set the target heating temperature on the control unit.
for ends
heating– Switchon theheating
Top heating temperature >> see splice data sheet

Splice pitch

110 x 11.5 mm

Splicing tool

SMX-HC-140/40 (handling explained in operating instructions)

Bottom heating temperature >> see splice data sheet– Wait till the target heating temperature has been reached.

There are splicing instructions (1) for every splicing method (seeChapter 7.2) for Siegling Extremultus flat belts. The instructions
describe the workflow starting with the preparation of the belt material right down to the removal of the finished splice.
The splicing instructions are supplemented by splicing data sheets (2).
They contain precise descriptions of the heating process for each product, including indications for time and temperature as well as thenames of auxiliary splicing materials (e.g. structural mesh, adhesives).
The splicing instructions and data sheets can be called up from thein-house splicing database B_Rex/Splice_It (3).
Avoiding errors when creating splices starts by carefully reading the
splicing instructions and data sheets. In accordance with these documents, prepare the required accessories and check that they function
properly.
While some accessories, such as the splice guide, are easy to check,
accessories prone to wear and tear require special attention.
Is the adhesive still usable, for example?
Is the structural mesh clean and unworn?
The belt ­material must also be carefully prepared. In addition, thelength must be correctly determined (see Chapter 5.2) and cut. The
belt width must also be cut accurately.
Finally, it is essential to punch, cut and grind the immediate splicing
area. Ensure that you are using suitable cutting blades, abrasives andgrinding machines.

Preparation tools:

PP-ZP-V/… (handling explained in operating instructions)

Accessories

Thermometer

Safety knife

Thickness sensor

Measurement tapeAngle gauge

Silver pen

Splice guides

Cleaning equipment

Brush

SpiritCleaning cloth

clamp drops to start with and then rises again.
Timerb) At a distance of > 0 mm: Place markings on the Z-splice.The
Pullhold-down
the ends ofthestarts
spliceafter
apartatset target heating temperature has been reached.
time
the

Thickness allowance>> see splice data sheet

Splice allowance

Length of splice pitch (= punching length)

Cutting bar

the markings until the required distance is created. Affix the ends of the belt with clamps onto
the splice guide.6

Heating the ends

– Keep to the stipulated hold-down time. Hold-down time >> see splice data sheetof the spliceand if necessary fixation area (only for the first punch of a series)
Cut-off length

Please note: By using the cold splice guide in the heating clamp, the temperature in the heating

For a series of punches: Length measured over the drive pulleys + thickness allowance

Please note: If operated constantly the tool can get hot. There is a risk of burns.

Single punching: Length measured over the drive pulleys + thickness allowance7+ splice allowance

Cooling the splice– After completing the heating period/hold-down time, switch off the heating clamp.
– a) Let the material in the heating clamp cool down completely.
Or

Caution: These splicing instructions may only be used in conjunction with the current splice– b) Take out the material cooled to about 100 °C with the splice guide from the heating clamp.

data sheet for the type of belt required. Splicing procedures,splice type,splicewith
pitch– Coverthe splice
theandtop part of the splice guide.

Put a cooling clamp onto the splice guide straightaway.

splice tool must be the consistent in both documents.

Caution: When applying the cooling clamp, ensure that both the top and bottom of

Caution: All the following descriptions assume that the friction layer/functional layer of thethe areas to be cooled are placed completely on the splice guide.

material is at the bottom and the top face/friction layer is at the top. If it is the other way
round (underside at the top, top face at the bottom) the layout of the press described must

– Once the cooling period has elapsed (usually 3 minutes or lukewarm) take off the two

be carried out in reverse.

clamps and the cooling clamp.

Caution: Only use all the tools, equipment and machinery in accordance with theappropriate operating instructions.

Please note: The cooling down period can be cut drastically by using several cooling clamps.

8 Taking the belting material– The belt is now ready for use.
– When inserting the splice
into theheating clamp makesure note:
it is positioned
inriskthe of burns from the splice guide.
3 Inserting the splice guideout ofguidethe splice
guide
PleaseThere is a
middle between the areas to be heated. This ensures total contact over the area between
into the heating clamp– Punch the ends of the belt with a punch press from the PP-ZP-V/….
series.
the spliceguide and heating clamp.

Procedure
1

Preparing/punching

Punching pitch >> see splice data sheet
L = Length measured over the drive pulleys + thickness allowance

4

Press pressurea) Standard by hand:– Close the heating clamp (turn the star grip screw clockwise).
– Tighten the star grip screw by hand in order to create the required pressure in the press.
b) In some cases with a torque wrench:
Torque >> see splice data sheet

Instructions no. 407_00_EN; 07/11 · Reprinting, duplication – even parts thereof – only with our permission.
Subject to change · Forbo Siegling GmbH · Lilienthalstrasse 6/8 · D-30179 Hannover · www.forbo-siegling.com
Page 1/3

Instructions no. 407_00_EN; 07/11 · Reprinting, duplication – even parts thereof – only with our permission.
Subject to change · Forbo Siegling GmbH · Lilienthalstrasse 6/8 · D-30179 Hannover · www.forbo-siegling.com
Page 2/3

Instructions no. 407_00_EN; 07/11 · Reprinting, duplication – even parts thereof – only with our permission.
Subject to change · Forbo Siegling GmbH · Lilienthalstrasse 6/8 · D-30179 Hannover · www.forbo-siegling.com
Page 3/3

Splicing
Data sheet
Article number
Belt type
Product group
Splice procedure
Splice type

28.Mai 2015, HannoverThis data sheet was generated automatically and is only valid when the articles and parametersstated below are combined.

822126
GG 30E-25 NSTR/FSTR grey/black
Extremultus
Melt splice
Z-Splice 70:11,5 without splicing accessories, 90°

Splice devices

SMX-HC-140/40

Preparation device
allowance in length
Surface pressure [N/cm^2]

PP-ZP-...(Z-punching tool),
8 [mm]
35 [N/cm^2]

Pitch of Z fingers
Splice parameters

Bars / tolerance
Assembly to heat0 [mm]
upper heating temperature

170 [°C]

lower heating temperature

170 [°C]

temperature hold time[mm]

00:01:00 [min]Upper clamp
Upper heating plate
Cover plate form guide
Fine structured fabric pink
Material
Fine structured fabric pink
Lower heating plate
Lower clamp

Details

Please note: heat heating clamp to target temperature before joining the splice. Please note:heating time starts when target temperature reached; Cooling in the press up to 120 ° C; thenput in cooling tong and cool to about 40 ° C-Before connecting please heat a sample connection.

Reprinting, duplication - even parts thereof – only with our permission. Subject to change.
In selecting the right instructions from Splice_IT, users must take into account the conveyor and the application concerned. All the splicing details refer to Forbo Siegling products in combination withthe finishing tools approved by Forbo Siegling. Should you have any questions or are uncertain about anything please refer to your contact at Forbo Siegling.
Forbo Siegling GmbH - Lilienthalstraße 6/8, D-30179 Hannover - www.forbo-siegling.com, printed 08.Feb 20192

Check the following, depending on the type of splice:
Wedge splice – Are the belt ends grinded at uniform angles?
Z-splice – Are the Z-edges completely punched through and straight?
Are the belt ends aligned in a row?

3

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If the preparatory steps have been carried out precisely, the key toa good splice is applying the adhesive to the belt ends (for wedge
splices) and/or observing the parameters indicated: pressure, tem­
perature, time.
The pressure is usually specified by the heating device. The tem­
perature and time parameters, on the other hand, can be adjusted
by the user. They can be taken from the splicing data sheet and set
accordingly on the heating device (4).
Forbo Movement Systems recommends always creating a test
splice in order to try out all of the steps in the splicing process.
After the belt has cooled (see splicing instructions and data sheet)and has been removed from the splice guide, the splice edges canbe straightened.
The belt is now ready for use. Please follow the information in
Chapter 6 regarding the handling of flat belts:– Storage– Condition of machinery– Fitting and tensioning– Care and handlingIf you require help creating an endless splice for a specific Siegling
Extremultus flat belt, please contact your local Forbo Movement
Systems representative:
www.forbo.com/movement > Contact
We will be pleased to help you.

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4

7.4 Fabrication options

In addition to creating endless splices, another area of fabrication involves adding other features to the Siegling Extremultus
flat belts. “Other features” refers here to applying profiles, creating perforations and the special processing of belt edges aswell as applying labels.
Not all of the other features make sense or are technically feasible for all Siegling Extremultus flat belts so please contact
your local representative to discuss any special requests in detail:www.forbo.com/movement > Contact
We will be delighted to help.

ProfilesBelt edge processing

Profiles are usually not welded to the extremely thin
Extremultus belts. Profiles are not common, particularly withpower transmission belts. Generally speaking, longitudinal
profiles can be used for better control and lateral profiles
can be used depending on the top coating of the flat belt.
However, profiles are only used with flat belts involved inconveyor tasks.

Belt edge processing on Siegling Extremultus flat belts withfabric tension members is possible in principle but is onlyused in special cases e.g. in the food industry or with textile
machines. Fray free operation is the main goal, as well as
offering some protection to the tension member against
the flat belt running up against machinery parts during
operation.

Perforations

Belt edge designs

Any conceivable perforation can be made according to cus­
tomer requirements. The perforations are usually made on
Siegling Extremultus flat belts that are used as vacuum
belts. Forbo Movement Systems supplies these belts mainly
to the printing and pulp and paper industry.

The “sawn edge” on heavy belts in the polyamide line is a
special type of belt edge design. This type of belt edge
design makes sense if the flat belt is fed in from the side ormust be moved laterally in transmissions during operation
as the sawn edge is considerably more robust than the cutedge of the polyamide tension member in the case of later­
al run-up.

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Labelling
For many applications, applying lettering and images is desirable.
Forbo Movement Systems boasts a variety of technical methods tochoose from depending on the application and scope of the labelling.
– Films: heating films on the belt surface– Printing: applying particles to the belt surface,e.g. inkjet printing– Laser labelling: using a laser to change the color of the surface
Labelling essentially performs the following functions:
Automation
In automated processes, markings can be recognized by opticalsensors. The conveyed product is precisely positioned or precisely
controlled during processing.
SafetyHigh contrast markings ensure good visibility on a moving belt,
contributing to accident prevention.
Advertising
The application of any text or image provides customers with
eye-catching and unmistakable branding.
Identification
Important information such as technical data, belt properties andorder codes can be applied to make it easier for the user to reorder
the belt and comply with legal regulations.
Laser labelling in particular offers many advantages. The labels are
extremely resistant, accurately positioned and highly refined. It is also
economical, even for small print runs.
Laser labelling is ideal for belts that are in direct contact with unpack­aged food in accordance with the FDA regulation 21 CFR as well as
the European regulation (EU) 10/2011 and (EC) 1935/2004.
Contact your local representative for more information about belt
labelling:www.forbo.com/movement > Contact

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8 	Pulleys

8.1 Pulley geometries
8.2 Dimensions and quality of pulleys
8.3 Use of crowned pulleys

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8.1 Pulley geometries

A huge advantage with flat belt drives is the simple
geo­metry of the pulleys used, unlike drives with V-belt
and V-ribbed belts.
Forbo Movement Systems recommends the use of cylin­
drical or crowned pulleys. In special cases (e.g. a cone drive),
conical pulleys are also permitted.

Cylindrical

CrownedConicalPointedTrapezoidal

Excessively crowned

Avoid sharp edges on the pulleys at all costs. For this reason,
pulleys with trapezoidal, cylindrical-conical or even pointed
designs are not suitable.
Also avoid excessive crowning to guarantee maximum belt
durability. The crown height values h recommended by
Forbo Movement Systems are listed in the following table.
Using pulleys in line with ISO 22 ensures belt durability,
optimal power transmission, good belt tracking and low
shaft loads.
Note: For pulley diameters > 2000 mm, we recommend
contacting Forbo Movement Systems applications engineers
regarding the crown height.

Crown height „h“ as per ISO 22

Pulley diameter d [mm]

d

h

b

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Extremultus Compendium · 01/2019

Crown height h [mm]for pulley widthb ≤ 250 mm
b > 250 mm

40

to

112

		

0.3

125

to

140

		

0.4

160

to

180

		

0.5

200

to

224

		

0.6

250

to

280

		

0.8

315

to

500

		

1.0

560

to

710

		

1.2

800

to

1000

1120

to

1400

1.5 		 2.0

1600

to

2000

1.8 		 2.51.2 		 1.5Pulleys with flanges
In some cases it may be necessary to use flanges on the pulleys.
As a general rule, however, Forbo Movement Systems advises against
the use of flanged pulleys.

h1bNote: Do not use flanged pulleys to control the flat belt!

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If the use of flanged pulleys is unavoidable, ensure that the face ofthe pulley is crowned in accordance with ISO 22 (see table on previouspage). In addition, the inner edges of the flanges must feature anundercut of 5° and all edges must be rounded. These measures
ensure that the flat belt never touches the flanged pulley as thiscan damage the flat belt.
h1 ≥ 20 mm

8.2 Dimensions andquality of pulleys
The width of the pulley b is calculated from the width of
the flat belt ”b0“ used. Following ISO 22, Forbo Movement
Systems recommends the minimum pulley widths “b” forthe line of belt widths (see table).
For pulley width which are not shown in this table following
formula can be used:b ≥ 1.1 · b0
The minimum diameters of the pulleys permitted for use
in the machinery depend on the flat belts used and are
indicated in the respective Siegling Extremultus flat belt
product data sheets.
In principle, the pulley faces should have an averageroughness of Ra ≤ 6.3 μm (according to DIN EN ISO 4287
and DIN EN ISO 4288). Surfaces with an average roughnessof Ra ≤ 3.2 μm, however, are not recommended, especiallyas drive pulleys. The risk of slippage exists here, potentiallyleading to a decrease in the transmission of power.
Normal pulleys can be used for speeds up to vmax = 40 m/s.
Special pulleys must be used for higher speeds (e.g. steel,counter-balanced).

78

Extremultus Compendium · 01/2019b0  [mm]b  [mm]b0  [mm]b  [mm]

20

25

180

200

25

32

200

225

30

40

220

250

35

40

250

280

40

50

280

315

45

50

300

315

50

63

320

355

55

63

350

400

60

71

380

400

65

71

400

450

70

80

450

500

75

90

500

560

80

90

550

630

85

100

600

630

90

100

650

710

95

112

700

800

100

112

750

800

120

140

800

900

140

160

900

1000

160

180

1000

1120

8.3 Use of crowned pulleys

2-pulley drives
As a general rule, both pulleys in a 2-pulley drive should bedesigned with a crown height as per ISO 22. However, fordrives with horizontal shafts and ratios of more than 1:3, thesmaller pulley can be cylindrical.

aMulti-pulley drives
In multi-pulley drives, only the pulleys that bend the flat
belts in the same direction should be crowned. The pulleys
located on the “inside” are generally best suited for this.

e

c
d

b

f

a

g

c
d

b

With shorter belt lengths, however, it is often sufficient tocrown only the largest pulley to ensure reliable belt tracking.

gf

In example 1, we recommend crowning pulleys a, c, e, f andg. With shorter flat belts it is sufficient to crown only a and e.

e

1

In example 2, we recommend crowning pulleys a, c and d.
For short belt lengths, a crowned version of “a” is sufficient.

c

a

b

c

d
2

a

b
d

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80

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9	Calculation of
power trans­mission belts
9.1 General information
9.2 Power transmission on flat belts
9.3 Terminology
9.4 Calculation method
9.5 Operating factor c2
9.6 Basic elongation at fitting c4
9.7 Elongation allowance for centrifugal force c5
9.8 Vibration calculation
9.9 Calculation example

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9.1 General information

This chapter contains up-to-date formulae, figures andrecommendations based on our longstanding experience.
They apply to power transmission between friction layers
G elastomer, or chrome leather and steel/cast iron pulleys.
The results of these calculations may however vary fromthose provided by our B_Rex calculator (see Chapter 4.5).
These deviations are a result of the fundamentally different
approaches: while B_Rex is based on empirical measure­ments and requires a detailed description of the machinery,the calculation methods shown here are based on general,
simple physical formulae and derivations, supplemented bycertain safety factors (e.g. c2).

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In most cases, the safety factor in calculations in thisbrochure will be greater than in the corresponding B_Rex
calculation.
Note: Siegling Extremultus flat belts from the polyurethaneline are not primarily designed for transmitting power andthe relevant data cannot be calculated using these formulae

9.2 Power transmission
on flat belts
For force-fit transmission of a given torque M and thus aneffective pull FU, the flat belt must be pulled tight against
the pulley. This creates a force which acts on both the tightand slack side of the belt (F1 and F2) and acts as a reaction
force on the pulley shafts. This force is known as the shaft
load FW (see also Chapter 2.6).
The friction helps transfer the effective pull FU from thedriving pulley to the driven pulley via the contact between
the flat belt and the pulley. In so doing, the pull F1 and thus
the elongation on the tight side of the belt is higher thanthe pull F2 and the elongation in the slack side of the belt.
These elongation differences in the flat belt are compensat­
ed for by the slip s.
As shown in the diagram below, there are three slip areas:
the creep area, the creep and slippage area and the slippage
area. In this case, slippage refers to the flat belt gliding, orslipping, on the pulley. Avoid operating the flat belts in theslippage area at all costs as this significantly reduces theservice life of the flat belt. Neither can slippage be fully elim­
inated when operating in the creep and slippage area sothis operating area should also be avoided.

Creep, however, means that the elastic material behaviourof the flat belt compensates for the force and elongationdifferences in the belt strands (F1 and F2) generated by theeffective pull FU. There is no excessive wear to the flat belt
as a result.
Siegling Extremultus flat belts (polyamide line) are designed
to reach their nominal effective pull FU Nenn at a defined
elongation at fitting, the nominal elongation at fitting
ε Nenn, and at a slip value of s = 0.6 %. If the flat belts areoperated at their intended operating point, they are always
working safely in the creep area. This area covers a slip ofabout s = 0.9%, meaning that in extreme cases the Siegling
Extremultus flat belts can transmit up to 150 % of their nom­
inal effective pull FU Nenn. This ensures that Siegling
Extremultus flat belts always reliably transmit power to thecustomer’s complete satisfaction. Different applications
require different flat belt widths. In order to categorize theflat belts, the nominal effective pull in the data sheet is indi­cated as width-based nominal effective pull F’U Nenn – basedon a width of 1 mm.
Note: Slippage areas depend on the material of the flat belt
used. Therefore, Siegling Extremultus flat belts in the aramide
and polyester lines have different slip values than flat belts inthe polyamide line.

Effective pull ratio FU/FU Nenn [%]Power transmission
e.g. Polyamide line

d2

150 %
Nominal effective pull

100 %Creep area

F1

FW
F2

Creep and slippage area
Slippage area
0

0,6

1
Creep s [%]83

d1

Extremultus Compendium · 01/2019

2

3 45

e

n2

9.3 Terminology

Abbreviation Unit

DesignationbmmWidth of pulley ringb0mm

Width of the flat belt

c2–

Operating factor

c4%

Basic elongation at fitting

c5%Elongation allowance for centrifugal force

cinitial–

Running-in ratio

cR

N/m

Spring constant of the flat belt

d1

mm

Diameter of the driving pulleyd2

mm

Diameter of the driven pulley

dsmallmm

Diameter of the smallest pulleyemmDistance between shafts/pulleys

F1

N

Tensile force – tight side of the belt

F2

N

Tensile force – slack side of the belt

FB

N

Reference force

FU

N

Effective pull to be transmitted

F’U

N/mm

Width-based effective pull

FU NennN

Nominal effective pull at nominal elongation at fitting

F’U Nenn

N/mm

Width-based nominal effective pull at nominal elongation at fitting

FW

N

Shaft load

F’ W

N/(mm · %)Width-related shaft load at 1% elongation at fitting

FWd

N

Dynamic shaft load

FW initial

N

Initial value of the shaft load

FW maxN

Permissible maximum shaft load (depending on machinery)

FWs

N

Static shaft load

f1

HzTransversal eigenfrequency tight side of belt

f2

HzTransversal eigenfrequency slack side of belt

ferr

Hz

Exciter frequencyhmm

Crown height

J1

kgm²

Mass moment of inertia of the driving pulley

J2

kgm²

Mass moment of inertia of the driven pulleylmm

Geometrical belt lengthl1mm

Arc length on the driving pulleyl2mm

Arc length on the driven pulleylS

mmFreely vibrating belt length

M

Nm

Torquem’

kg/m²

Weight per surface unit of the flat belt

m’R

kg/m

Weight per metre of the flat belt

n1

1/min

Speed of the driving pulley

n2

1/min

Speed of the driven pulley

P

kW

Power to be transmittedv

m/s

Belt speed

zerr

–

Number of excitation cycles per belt revolution
Arc of contact at the driving pulley

β1

mm

β2

mm

Arc of contact at the driven pulleyε%Elongation at fitting

ε Nenn%Nominal elongation at fitting

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9.4 Calculation method
Known are: P [kW], d1 [mm], n1 [1/min], d2 [mm] and e [mm]1

Arc of contact β1 and β2

2 Effective pull to be transmitted F[°]

β2 = 2 · arccos ((d1 – d2)
2e )

[°]

n
d1
· 1
1000 60

P · 1000
v

FU =

U

[m/s]
[N]

B

FB = FU · c22

Read off c2 from the “Operating factor” table (see Chapter 9.5)

force F
3 Reference
operating factor cWidth-based Effective pull F’U
width-based Nominal effective pull F’U Nenn
Basic elongation at fitting c4
Flat belt preselection

5 Width of the flat belt b

6[N]

In the diagram of dsmall going vertically to the top until it intersects with β, read off F’U,
to the left and c4 and F'U Nenn to the right.
A suitable product is preselected based on the width-based nominal effective pull of F’U Nenn.

FB
F’U

b0 =

0

Arc length at the driving pulley l1 anddriven pulley l2[mm]

l1 = π ·

d1 β1
·
2 180

[mm]

l2 = π ·

d2 β2
·
2 180

[mm]

√

(d2 – d1)24Freely vibrating length ls

ls = e2 –Geometrical belt length l

l = l1 + l2 + 2 · ls

Elongation at fitting εε = c4 + c5

force c5

Read off c5 from the tables “Elongation allowance for centrifugal force” for the selected Siegling
Extremultus flat belt (Chapter 9.7)

Shaft load FW
At a standstill (static) FWs
While operating (dynamic) FWd

FWs = ε · F’w · b0
FWd = c4 · F’w · b0

[N]
[N]

FW initial = cinitial · ε · F’w · b0[N]

7 Elongation allowance for centrifugal
8 Initial value of shaft load F

W initial

[mm]
[mm]

Note: The length of the flat belt to orderdepends on the elongation at fitting(see Chapter 5.2. and Chapter 6.3)[%]

Note: Read off F’W from the data sheet(see Chapter 2.5)

Running in ratio c initial

Read off cinitial from the table Running-in ratio in Chapter 6.3

Vibration calculation
exciter frequency ferrnferr =· zerr[Hz]	Use the speed of the pulley with the60		highest mass imbalance for n.

Weight per meter of the flat belt m’R

b0m’R = m’ ·[kg/m]
1000
		

Belt force on tight side of the belt F1

F1 =FWs + Fu
2

[N]

F2 =

FWs – Fu
2

[N]

Transversal eigenfrequency:
on the tight side of the belt f1

f1 =

1000
ls

F1
4 · m’R[Hz]

on the slack side of the belt f2

f2 =

1000
ls

F2
4 · m’R[Hz]

9 Belt force on slack side of the belt F

285(d2 – d1)2e )v = π·

Belt speed v

4

β1 = 2 · arccos (Extremultus Compendium · 01/2019

Read off m’ from the data sheet for 		the respective Siegling Extremultus Flat Belt.

9.5 Operating factor c2

Type of drive

Examples of drives

Operation
factor c2

Consistent operation
Small masses to be accelerated
Load-free acceleration

Generators with low capacity
Centrifugal pumps
Automatic lathes
Lightweight textile machinery

1.0

Almost consistent operation
Medium-sized masses to be accelerated
Usually load-free acceleration

Small fans up to 8 kW
Tool machines
Rotary piston compressor
Wood processing machinery
Light and medium-weight
Generators
Grain mills
Multi-stage gearbox
Carding machines
Extruders
Stone frame saws
Screw-type compressors

1.2

Irregular operation
Medium-sized masses to be accelerated
Sudden force

Piston pumps, compressors
Degree of uniformity > 1:80
Centrifuges
Large pressure pumps
Fans
Kneading machines
Beaters
Crushing mills
Pebble mills
Tube mills
Looms
Agitators
Cutting machines wood industry
Vehicle body presses
Conical belts paper industry

1.35

Irregular operation
Large-sized masses to be accelerated
Substantial sudden force
Acceleration under load

Piston pumps, compressors
Degree of uniformity > 1:80
Wood frame saws
Jolters
Excavator drives
Edge runners
Rolling machines
Brick presses
Forging presses
SheersPunch presses
Roller mills
Stone crushers
Flakers

1.7

Depending on drive’s torque, the following minimum parameters during operation must be kept to:
Drive

Minimum value c2

Speed-controlled electric motors (e.g. frequency converters)

1.0Electrical motors with Y-delta connection
Electrical motors with mechanical, or hydrodynamic clutch
Pole-changing electrical motors
Combustion engines
Water turbines

1.3

Electrical motors, directly switched on without centrifugal clutch

1.7

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9.6 Basic elongation at fitting c4
Polyamide line – Sheet
only at low
speed

F’U [N/mm]

F’U Nenn [N/mm]

Ideal elongation
at fitting

Calculation example
Chapter 9.9
F’u Nenn= 40 N/mm
selected

β = 144 °enlarged area
see below

dsmall = 450 mm

dsmall [mm]c4 = 2.25 %Basic elongation fitting c4 [%]only at low
speed

F’U [N/mm]

F’U Nenn [N/mm]

Ideal elongation
at fitting

dsmall [mm]87

Extremultus Compendium · 01/2019

Basic elongation fitting c4 [%]9.6 Basic elongation at fitting c4

If possible avoid elongation areaF’U Nenn [N/mm]

















Polyester line – Fabric



















F’U [N/mm]



















enlarged area
see below                   dsmall [mm]        

Basic elongation fitting c4 [%]If possible avoid elongation area
















































F’U [N/mm]F’U Nenn [N/mm]














dsmall [mm]

















Basic elongation fitting c4 [%]Info about the Polyester line: where belts have U coating, due to the low structural strength of the Polyurethane, the transferrable effective pull must be reducedby 1/3. Depending on the type, basic elongation at fitting of > 2.0 % is possible, but Forbo Movement Systems should be consulted.

88

Extremultus Compendium · 01/2019

Polyester line – Cord
















Ideal elongation
at fitting





















F’U Nenn [N/mm]








F’U [N/mm]
















                              dsmall [mm]Basic elongation fitting c4 [%]Info about the Polyester line: where belts have U coating, due to the low structural strength of the Polyurethane, the transferrable effective pull must be reducedby 1/3. The belts can be subjected to extreme stress and when they have a rubber friction layer, they may fall below the diameter thresholds shown in the diagram.
Where heavy-duty drives are concerned, we recommend you talk to Forbo Movement Systems application engineers.

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9.6 Basic elongation at fitting c4
Aramide line – Fabric

































F’U Nenn [N/mm]

F’U [N/mm]













enlarged area
see below                    dsmall [mm]


























Basic elongation fitting c4 [%]
























F’U Nenn [N/mm]

F’U [N/mm]


















dsmall [mm]





















Basic elongation fitting c4 [%]Info about the Aramide line: where belts have U coating, due to the low structural strength of the Polyurethane, the transferrable effective pull must be reducedby 1/3. Depending on the type, basic elongation at fitting of > 0.8 % is possible, but application engineers at Forbo Movement Systems should be consulted.

90

Extremultus Compendium · 01/2019

Aramide line – Cord































Ideal elongation
at fitting









F’U Nenn [N/mm]

F’U [N/mm]
























dsmall [mm]























Basic elongation fitting c4 [%]Info about the endless Aramide line: The belts can be subjected to extreme stress and when they have a rubber friction layer, they may fall below thediameter thresholds shown in the diagram. Under certain conditions, the transferable effective pull can also be increased far above the nominal effective
pull. Where heavy-duty drives are concerned, we recommend you talk to Forbo Movement Systems application engineers.

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9.7 Elongation allowance for	centrifugal force c5
Polyester line
F’U Nennv [m/s]
30

40

50

6

0.1

0.15

0.2

10

0.1

0.15

0.2

15

0.1

0.15

0.2

20

0.1

0.15

0.2

25

0.1

0.15

0.2

30

0.1

0.15

0.2

40

0.1

0.15

0.2

F’U Nennv [m/s]
40

50

60

10

0.1

0.2

0.3

14

0.1

0.2

0.3

20

0.1

0.2

0.3

28

0.1

0.2

0.3

40

0.1

0.2

0.3

F’U Nennv [m/s]
30

40

50

60

10

0.1

0.15

0.2

0.25

14

0.1

0.15

0.2

0.25

20

0.1

0.15

0.2

0.25

28

0.1

0.15

0.2

0.25

40

0.1

0.15

0.2

0.25

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Tension member design: Fabric;coatings: all
In the polyester line, the elongation at fitting ε may notexceed 2.1 %.

Tension member design: Cord;
coatings: GT, GG, UU
For endless belts in the polyester line, the elongation at
fitting ε may not exceed 1.5 %.
For belt speeds over 60 m/s, we encourage you to contact
Forbo Movement Systems application support.

Tension member design: Cord;
coatings: LT, LL
For endless belts in the polyester line, the elongation at
fitting ε may not exceed 1.5 %.
For belt speeds over 60 m/s, we encourage you to contact
Forbo Movement Systems application support.

Aramide line
F’U Nenn

Tension member design: Fabric;coatings: all
In the aramide line, the elongation at fitting ε may notexceed 1 %.

v [m/s]

15

40

50

0.05

0.05

25

0.05

0.05

40

0.05

0.05

F’U Nenn

Tension member design: Cord;
coatings: GT, GG, LT
For endless belts in the aramide line, the elongation at
fitting ε may not exceed 1 %.
For belt speeds over 60 m/s, we encourage you to contact
Forbo Movement Systems application support.

v [m/s]
40

50

60

54

0.05

0.05

0.1

80

0.05

0.05

0.1

Polyamide line
F’U Nennv [m/s]
20

30

40

50

60

70

6

0.2

0.3

0.7

1.0

*

*

10

0.2

0.3

0.6

0.9

*

*

14

0.1

0.3

0.5

0.8

1.0

*

20

0.1

0.3

0.4

0.7

1.0

*

28

0.1

0.2

0.4

0.6

0.8

*

40

0.1

0.2

0.3

0.5

0.7

1.0

54

0.1

0.2

0.3

0.5

0.7

0.9

80

0.1

0.2

0.3

0.4

0.6

0.8

F’U Nennv [m/s]
20

30

40

50

60

70

6

0.3

0.6

1.0

*

*

*

10

0.2

0.5

0.8

*

*

*

14

0.2

0.4

0.6

1.0

*

*

20

0.1

0.3

0.5

0.9

1.0

*

28

0.1

0.2

0.4

0.7

0.9

*

40

0.1

0.2

0.3

0.6

0.8

1.0

54

0.1

0.2

0.3

0.5

0.8

1.0

65

0.1

0.2

0.3

0.5

0.7

0.9

80

0.1

0.2

0.3

0.5

0.7

0.9

Tension member design: Sheet;coatings: GT
For belts in the polyamide line, the elongation at fitting ε
may not exceed 3 %.

Tension member design: Sheet;coatings: LT
For belts in the polyamide line, the elongation at fitting ε
may not exceed 3 %.

* For belt speeds of 70 m/s and higher, we recommend you always ask Forbo Movement Systems to support you in selecting the right
Siegling Extremultus Flat Belt type.

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9.8 Vibration calculation

A flat belt drive is a dynamic system which can vibrate. Depending on the application, the system is periodically
excited by the driving and/or driven machine, resulting in transversal and/or longitudinal vibrations.
To avoid unwanted effects such as shortened service life, the periodic exciter frequency may not be near the eige­n­frequency of the flat belt. This so-called resonance is a relatively rare occurrence thanks to the outstanding damping
properties and resulting low eigenfrequency of Siegling Extremultus flat belts.
However, we do recommend that vibration calculations for longitudinal vibrations be carried out by Forbo Movement
Systems, in particular for piston compressors, water turbines (Kaplans, Francis), multiple blade frame saws or similar
components.

Bending frequency
The maximum permissible bending frequency depends onthe design of the flat belt. When the bending frequency is
too high, the service life of a flat belt can be shortened andthe noise generated by the endless splice running up onto
the pulley can be considerable. In the event of high bending
frequencies, wedge splices in the polyamide line should
always be 60°.
Forbo Movement Systems should always be consulted in
the event of bending frequencies above 30 Hz.

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Longitudinal eigenfrequency

Transversal eigenfrequency

The longitudinal eigenfrequency of a flat belt depends on
the spring rate of the flat belt cR and on the mass moments
of inertia (J1) of the driving and driven pulley (J2).

The transversal eigenfrequency of a flat belt depends onthe freely-vibrating belt length lS, the force in the belt strand(tight side of the belt F1, slack side of the belt F2) and theweight per metre of the flat belt m’R.

In terms of measurement, it is very difficult to show longi­
tudinal vibrations. Signs of longitudinal vibration include
excessive wear of the underside of the flat belt, polishedpulley surfaces and fine red powder. Existing longitudinal
vibrations can only be eliminated by using a flat belt witha different tension member material.
Resonance is avoided when the exciter frequency ferr differsfrom the eigenfrequency of the system by at least 30 %.

That means that the eigenfrequency on both the tight sideand the slack side of the belt are to be considered to obtaina complete vibration analysis.
Transversal vibrations are obvious – the flat belt flaps exces­
sively. This can be avoided by integrating a tangential roller(steady roller), or by changing the shaft distance or belt ten­sion.
Resonance is avoided if there is a difference of at least 20 %between the exciter frequency ferr and the flat belt’s eigen­frequency (on the tight side of the belt f1 and the slack sideof the belt f2).

ls

F

cR

J2

d1

J1

cR

95

d2

F

Extremultus Compendium · 01/2019e9.9 Calculation example

Motor capacity

P

Diameter of drive pulleyd1 = 450 mm= 280 kW

Motor speed

n1 = 1490 1/min

Center distancee

Diameter of driven pulleyd2 = 2000 mm

Speed of driven pulleyn2 = 335 1/min= 2500 mm

Ambient conditions are dusty, free of oil, normal temperature
Required: Power Transmission Belt for electrical drive in a gang saw

1 Arc of contact β and β12Belt speed v

2 Effective pull to be transmitted FU

β2 = 2 · arccos ((450 mm – 2000 mm)= 216.1°       )2 · 2500 mm

1490 1/min
450 mm·1000 mm/m 60 s/min= 35.1 m/s

280 kW · 1000 W/kW
35.1 m/s= 7976 N

v = π·FU == 13559 N

Read c2 = 1.7 off the “Operating factor” table (see Chapter 9.5)

2

Width-based Effective pull F’U
width-based Nominal effective pullF’U Nenn

4(2000 mm – 450 mm)      
) = 143.9 °2 · 2500 mm

FB = 7976 N · 1.7

Reference force FB

3 operating factor cβ1 = 2 · arccos (Basic elongation at fitting c4

On the basis of the ambient conditions, a Siegling Extremultus flat belt with polyamide sheet
and rubber coating can be used. The diagram for the polyamide line is evaluated:β143.9 °  F’U
45 N/mmc4
2.25 %F’U Nenn
40 N/mmdsmall = 450 mm = d1
Flat belt preselection

5 Width of the flat belt b

GT 40P black (850049) is preselected (see Chapter 4) based on the width-based nominal effective
pull of F’U Nenn = 40 N/mm.

0

Arc length at the driving pulley l1 anddriven pulley l2

6

b0 =

= 301 mm

l1 = π ·450 mm 143.9°= 565 mm·2180°

l2 = π ·2000 mm 216°
·
2
180°

Freely vibrating length ls

b0 = 320 mm is selected= 3772 mm

mm – 450 mm)
		√ (2500 mm)   – (20004= 2377 mm

l = 565 mm + 3772 mm + 2 · 2377 mm		= 9091 mmls =Geometrical belt length l13559 N
45 N/mm22

Note: The length of the flat belt to order depends on the type of tensioning (see Chapter 5.2
and Chapter 6.3)

96Extremultus Compendium · 01/2019

Elongation at fitting εallowance for centrifugal
7 Elongation
force c58

ε = 2.25 % + 0.25 % = 2.5 %c5 = 0.25 % read from the table for polyamide GT line (Chapter 9.7)

Shaft load FW

F’W = 40 N/mm for GT 40P black (850049) read off data sheet (see Chapter 2.5).

At a standstill FWs

FWs = 2.5 % · 40 N/(mm · %) · 320 mm		= 32000 N

While operating FWd

FWd = 2.25 % · 40 N/(mm · %) · 320 mm		= 28800 N

Initial value of shaft load FW initial

FW initial = 2.2 · 2.5 % · 40 N/(mm · %) · 320 mm= 70400 N

Running in ratio cinitialcinitial = 2.2 read from the table running-in ratio in Chapter 6.3

Vibration calculation

Like all crank drives, a gang saw transmits power unevenly. For every rotation of the drive pulley,
it carries out 2 working strokes (= zerr).

Vibration calculation ferr

335 1/minferr =     · 260 s/min= 11.2 Hz

Use the speed of the driven pulley for n.

Weight per metre of the flat belt m’R

320 mmm’R = 4 kg/m2 ·= 1.28 kg/m Read off m’ from the data sheet for the1000 mm/m
		respective Siegling Extremultus flat belt.

Belt force on tight side of the belt F1F1 == 19988 N

9 Belt force on slack side of the belt F

32000 N + 7976 N
2F2 =32000 N – 7976 N
2= 12012 N

Transversal eigenfrequency:
on the tight side of the belt f1

f1 =1000 mm/m
2377 mm19988 N
= 26.3 Hz
4 · 1.28 kg/m

on the slack side of the belt f2

f2 =1000 mm/m
2377 mm12012 N= 20.4 Hz
4 · 1.28 kg/m

2

The eigenfrequencies of the tight and slack side of the belt both differ by more than 20 %of the exciter frequency. There is therefore no risk of transversal vibrations (flapping)of the flat belt.

Solution: GT 40 P black (850049) is suitable for this application

97

Extremultus Compendium · 01/2019

98

Extremultus Compendium · 01/201910	Calculation ofLive Roller Belts
10.1 General information
10.2 Terminology
10.3 Calculation method

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Extremultus Compendium · 01/2019

10.1 General information

We always recommend designing live roller drive belts using
our calculation software B_Rex (see Chapter 4.5). The soft­
ware features prefabricated models for classic roller convey­
ors with rear or head drives (see image).

This chapter also contains a description of how to calculate
the design of live roller drive belts by hand.
To properly design a live roller belt, regardless of whether
you use the calculation software B_Rex or do the calculationby hand, a series of data about the machine and how it
operates is required. Ideally this information is provided by
the manufacturer and/or operator of the machine.
The information includes geometric data for the machinery(including the number and diameter of the conveying andpressure rollers, diameter of drive and drum pulleys, convey­
ing length, etc.) as well as information about loading andpossible accumulation. Further, it often includes require­ments regarding the belt thickness s, belt width b0 and themax. loading of the live roller from an existing machinery
design.

100 Extremultus Compendium · 01/2019

A list of these basic essential machine parameters can befound in the Siegling Extremultus application checklist.
Please contact your local representative for more infor­
mation:www.forbo.com/movement > Contact
Live roller belts should be designed based on thesemachine parameters. The design comprises the following
calculation steps:– Calculation of the effective pull
– Calculation of the belt width and elongation at fitting– Calculation of transmission of power at the drive pulley– Calculation of the arc of contact on the conveying rollers– Calculation of the engagement depth10.2 Terminology

Abbreviation Unit

Designationb0mm

Width of the flat belt

b0,actualmm

Selected width of the flat belt

b0,minmm

Minimum required width of the flat belt

dCR

mm

Diameter of the conveying rollers

ddrivemm

Diameter of the drive pulley

eCR

mm

Center distance between the conveying rollers

F'U Nenn

N/mm

Width-based nominal effective pull at nominal elongation at fitting

F'U Nenn,min

N/mm

Minimum required nominal effective pull (per mm of belt width)

FU,a

N

Effective pull resulting from acceleration

FU,accumulation

N

Effective pull resulting from accumulation

FU,bendN

Effective pull resulting from bending

FU,CR

N

Effective pull on one conveyor roller

FU,incline

N

Effective pull resulting from incline

FU,J

N

Effective pull resulting from inertia

FU,loadN

Effective pull resulting from load

FU,maxN

Maximum transmissible effective pull

FU,reqN

Required total effective pull

g

m/s²

Acceleration due to gravity

lconveym

Conveying length

m'L

kg/m

Line load

mCR

kg

Mass of the conveying rollers

mR

kg

Mass of the flat belt

nCR–

Number of conveying rollerssmmThickness of the flat beltx

mmInfeed of the pressure rollerymm

Engagement depth of the belt into the conveying rollersα°

Arc of contact between flat belt and conveying roller
Arc of contact between flat belt and drive pulley

β1

°

ε

%

Elongation at fitting

ε Nenn%Nominal elongation at fittingµr–

Coefficient of friction for rolling support

ρmax

N/mm²

Transmission capacity

101 Extremultus Compendium · 01/2019

10.3. Calculation method
Calculation of the effective pull
The effective pull required to safely operate the respective
live roller is made up of several elements. They include:–	Effective pull resulting from load (FU,load)–	Effective pull resulting from incline (FU,incline)

Calculation of the belt widthand elongation at fitting
Requirements for maximum belt width b0 are often set out
at the time of design, in other words by the machine manufacturer. The following equation is then used to calculate
the minimum nominal effective pull F’U Nenn,min required by
the belt for this application.

–	Effective pull resulting from accumulation (FU,accumulation)–	Effective pull resulting from inertia (FU,J)F’U Nenn,min =FU,reqb0–	Effective pull resulting from bending (FU,bend)–	Effective pull resulting from acceleration (FU,a)The required total effective pull FU,req is the sum of theeffective pull elements.
FU,req = FU,load + FU,incline + FU,accumulation + FU,J +FU,bend + FU,a
Depending on the topology and geometry of the machinery as well as the degree of contact between the conveying
rollers and the power transmission belt, the elements ofeffective pull can vary greatly from machine to machine.

Now select a belt from the B_Rex belt database or from theExtremultus Product Finder whose nominal effective pullF’U Nenn is greater than the minimum required nominal effective pull F’U Nenn,min.
F’U Nenn > F’U Nenn,min
The nominal effective pull of each product is listed in therespective data sheet (see Chapter 2.5).

However, in most cases there is no comprehensive data
available to calculate all of the effective pull elements. Thismeans that only the effective pull resulting from load canbe calculated using the following formula:

If there is no belt with an appropriately high nominal effective pull and/or the width can be varied, the above formulacan be transposed using b0 so that the minimum belt widthb0,min is calculated from the quotient of the required effective pull and the nominal effective pull of a selected belt
(selected from B_Rex or Extremultus Product Finder >application group: live roller belt):

FU,load = (lconvey · m’L + mR + mCR) · µr · g

b0,min =The friction coefficient for rolling support (running over aroller) can be assumed to be µr = 0.033.
To estimate the required total effective pull FU,req in ahorizontal conveyor system, the effective pull element forload FU,load is multiplied by an adjustment factor of 3.
FU,req ≈ 3 · FU,load

For good measure you should then select an actual belt
width b0,actual that is greater than the calculated minimum
belt width.
b0,actual > b0,min
The following formula can now be used to roughly calculate
the required elongation at fitting ε:ε=

102 Extremultus Compendium · 01/2019

FU,reqF’U Nenn

FU,reqF’U Nenn· b0,actual
ε NennThe nominal elongation at fitting ε Nenn is the elongation
at fitting used to determine the nominal effective pullF’U Nenn of the selected belt. This nominal elongation at
fitting is a function of the tension member material and canbe assumed as follows for the respective tension member
materials:
Tension member material

ε Nenn [%]Aramide0.8

Polyamide

2.0

Polyester

2.0This formula contains the variables– Arc of contact β1– Width of the flat belt b0– Diameter of the drive pulley ddrive
Changing these variables, in consultation with the customer,
can affect the maximum transmissible effective pull FU,max.
To ensure safe operation, the maximum transmissible effec­
tive pull FU,max must be greater than or at least equal to therequired total effective pull FU,req.
FU,max ≥ FU,req
To obtain the minimum limit of one of these variables, thediameter for example, transpose the formula according to
ddrive and use the required total effective pull FU,req for the
maximum transmissible effective pull FU,max. This results inthe following formula:

Calculation of transmissionof power at the drive pulley
The transmission of power between the flat belt and thedrive pulley is a function of the so-called transmission
capacity ρmax. The transmission capacity ρmax depends onthe material and refers to the tension member material
used. The ρmax values for the tension member materials
used by Forbo Movement Systems are listed in the following
table.
Tension member material

ρ max [N/mm2]

Aramide0.15

Polyamide

0.08

Polyester

0.10

To calculate the maximum transmissible effective pull FU,maxthat can be transmitted from a drive pulley with the select­
ed flat belt or tension member of the belt, the transmission
capacity ρmax must be multiplied by the contact surface
between the belt and the drive pulley. The formula used is
as follows:
ddriveπ · β1FU,max = ρmax ·    
180° · b0 ·2

103 Extremultus Compendium · 01/2019

ddrive ≥ 2 ·FU,reqπ · β1· b0 · pmax
180°

Using this method you obtain the minimum possible
drive pulley diameter for the required total effective pull
calculated.

10.3. Calculation method
Calculating the arc of contact on the conveying rollers
The next step is used to determine the arc of contact of theflat belt on the conveying rollers in order to guarantee thatthe transport task is safe and secure. To do this, estimate theeffective pull FU,CR that must be transmitted to a conveying
roller for safe operation.
If a pressure roller is always positioned between two conveying rollers (see diagram) and we can assume that thesame effective pull is transmitted to all conveying rollers,
dividing the required total effective pull FU,req by the number of conveying rollers nCR gives the effective pull FU,CR to
be transmitted to a conveying roller:
FU,CR =

To calculate the minimum arc of contact α, transpose theequation for the transmission capacity ρmax to solve for thearc of contact α:
α≥

FU,CR
π
dCR
· b0 ·· ρmax180°2Note: If the angle α selected is significantly greater, it may benecessary to recalculate the required effective pull (with a higher
adjustment factor) as the effective pull portion increases as aresult of the bending capacity (FU,bend).

FU,reqnCR

Calculating the engagement depth
Once the required arc of contact α to the conveying rollers
has been determined, the engagement depth y of the belt
into the conveying rollers and thus also the infeed x of thepressure rollers can be geometrically determined (see diagram):tan(α) =

y
eCR
(2)

e
y = tan(α) · ( CR )2
In addition to the arc of contact on the conveying rollers,
the center distance between the conveying rollers eCR isalso required for this calculation.

104 Extremultus Compendium · 01/2019

The infeed x of the pressure rollers is calculated by subtracting the belt thickness s from the engagement depth y of the
belt:
x=y–s

Note: When the infeed of the pressure rollers is x = 0 mm,
the engagement depth y is equal to the belt thickness s (seediagramm).
A live roller belt can be completely designed for the respective application using this formula. However, before making
a binding order we recommend having our experts checkthe calculation. Please contact your local representative:
www.forbo.com/movement > Contact

Conveying roller
CR

Conveying rollersy = x+sx

Live Roller Belt
Pressure roller
CR

CR

Center distance

Note: A good start value for a live roller belt calculation is an engagement depth y equal to half of the belt thickness s.
y = s/2
x = y – s = s/2 – s = – s/2

105 Extremultus Compendium · 01/2019

106 Extremultus Compendium · 01/201911	Troubleshooting
11.1 Installation
11.2 Splice opening
11.3 Noise generation
11.4 Poor belt tracking
11.5 Wear
11.6 Changes in properties

107 Extremultus Compendium · 01/2019

11.1 Installation

Description of the problem

Cause of the problem

Countermeasure

Comment/recommendation

Flat belt cannot be installed
or would have to beelongated too much

Ambient temperature too cold,
resulting in flat belt becoming
too stiff

Warm flat belt up just prior to
installation

The stiffness of plastic changes withthe temperature

Flat belt length incorrectly
measured (wrong order length)

Correctly measure required flat belt
length (see Chapter 5.2) and replaceflat belt

When ordering, the inner length of
the flat belt is crucial

Flat belt is easy to install but
cannot be brought tocalculated elongation at
fitting

Flat belt too long. Flat belt
length incorrectly measured(wrong order length)

Correctly measure required flat belt
length (see Chapter 5.2), shorten flat
belt if possible or replace

When ordering, the inner length of
the flat belt is crucial

Calculated value of the shaft
load exceeded by a significant
amountFlat belt relaxation notcomplete

Let flat belt run slowly with no load;
if necessary, tension in two stages(see Chapter 6.3)

The relaxation time for the Siegling
Extremultus flat belts can takeseveral operating hours

Calculated value of the
shaft load in steady state notreachedFlat belt was tensioned in manysmall stages (dead tensioning)

Replace flat belt;
Tension the new flat belt in twostages at most (see Chapter 6.3).
Avoid multi-stage tensioning (>2)

The shaft load/elongation behaviorof the flat belt changes whentensioning takes place in manysmall stages

Flat belt gets longitudinalgrooves and/or breaks in thelongitudinal direction

Flat belt bent when installedon pulley

Replace flat belt

Aramide tension members may not
be bent! Endless belts should be
carefully placed on pulleys. Avoid
longitudinal and transversal bends

108 Extremultus Compendium · 01/2019

11.2 Splice opening

Description of the problem

Cause of the problem

Countermeasure

Comment/recommendation

Splice opening with smoothjoint faces (wedge splice)

Faulty endless splicing

Replace flat belt

Check splicing parameters, adhesives
and heating device; splice according
to Forbo Movement Systems splicing
instructions

Splice opening with
splintered joint faces(wedge splice)

Endless splice overload

Replace flat belt

Tension Siegling Extremultus flat belts
only to the calculated elongation at
fitting

External mechanical influence

Replace flat belt and checkmachinery for stalled shafts,
bearings and pulleys as well as
for sharp edges that may comeinto contact with the flat belt

Due to the high relative speeds
between a flat belt in operation
and a stalled part of the machinery,such contact results in quick failureof the flat belt

Splice opening with smoothjoint faces (Z-splice)

Faulty endless splicing

Replace flat belt

Check splicing parameters andheating device; splice according to
Forbo Movement Systems splicing
instructions

Splice opening with frayedjoint faces (Z-splice)

Endless splice overload

Replace flat belt

Tension Siegling Extremultus flat belts
only to the calculated elongation at
fitting

External mechanical influence

Replace flat belt and checkmachinery for stalled shafts,
bearings and pulleys as well as
for sharp edges that may comeinto contact with the flat belt

Due to the high relative speeds
between a flat belt in operation
and a stalled part of the machinery,such contact results in quick failureof the flat belt

109 Extremultus Compendium · 01/2019

11.3 Noise generation

Description of the problem

Cause of the problem

Countermeasure

Comment/recommendation

Whistling noises

Slippage as a result of largetransmission ratio between
drive and driven (arc of contact
at the small pulley too small)

Change the geometry of themachinery or increase the arc ofcontact at the small flat belt pulleyusing snub rollers

Based on experience, a two-pulley
drive can start to whistle at a trans­mission ratio greater than 5:1

Squeaking noises(leather coating)Slippage due to hard,
shiny leather surface

Roughen leather surface with awire brush and apply Extremultus
spray paste. Re-tension polyamideline flat belt by approx. 0.2 %A highly compressed leather surface
cannot absorb grease. By roughening
the surface, the leather is capable ofabsorption once again

Squeaking noises(rubber coating)Load and thus creep too high

Recalculate and replace flat belt

Over the long term performance canonly be achieved with a larger belt
pulley diameter and/or wider flat belts

Banging/flapping noises

Splice causes flapping noises
but shows no signs of damage

No intervention necessary

Welded and bonded splices usuallyexhibit different bending stiffness
than the rest of the belt

Splice is damaged

Replace flat belt

See Chapter 11.2

110 Extremultus Compendium · 01/2019

11.4 Poor belt tracking

Description of the problem

Cause of the problem

Countermeasure

Comment/recommendation

Flat belt runs off ofthe pulley

Pulleysare not properly aligned

Align pulleys parallel andflush to one another

Misaligned pulleys(especially crowned pulleys)
result in significantly higher
loads and shorter belt life cycles.
If the flat belt runs over the edge
it is destroyed very quickly

Flat belt
overtensioned

Reduce belt tension (observe
recommended elongation at fitting)If the flat belts in the machinery
are tensioned too high, the shaftson the pulleys can be deflected,
causing the alignment of the pulleys
to change.

Cantilevered bearing:Calculate shaft deflection andincrease shaft diameter if necessary

Flat belt drifts,
flat belt regularly slides on
the pulley (moves fromone side of the pulley tothe other and back)Pulleys are dirty

Clean pulleys

Performing regular maintenanceon the machinery results in a longer
lifetime for the flat belts

Pulleysare not crowned

Lathe pulleys
into a crowned shape

For information on crown heights
see Chapter 8.1

The endless splicing in
the flat belt has a kink or
the flat belt is bowedCountermeasure only necessary
if the flat belt is required to run
extremely smoothly

During production it is not always
possible to guarantee the complete
absence of tension in the material.
This can result in a curvature of
the material. As a rule the curvature
flattens out with minimal elongation
at fitting, see Chapter 6.1
If it is necessary for the flat belt to
run extremely smoothly, this canbe achieved through measures
such as splicing flat belts in thebend or cutting off the belt edges
after splicing.

Flat belt slides on the pulleyirregularly (runs from one sideof the pulley to the other andback)

Cylindrical pulley
is grooved

Lathe pulleys,
avoid grooves

Grooves can cause a threading effectwhich influences the tracking of theflat belt

Crown of the pulley
incorrectly selected

Lathe pulleys
into a crowned shape

For information on crown heights
see Chapter 8.1

Pulleys are dirty

Clean pulleys

Performing regular maintenanceon the machinery results in a longer
lifetime for the flat belts

111 Extremultus Compendium · 01/2019

11.4 Poor belt tracking

Description of the problem

Cause of the problem

Countermeasure

Comment/recommendation

Flat belt flaps

Transversal vibrations (exciterfrequency corresponds to thetransversal eigenfrequency of
the flat belt)

Change belt tension (observe
recommended elongation at
fitting); change speed; change
freely-vibrating length(e.g. installation of steady roller)

In the worst-case scenario theresonance between the exciter andeigenfrequency can destroy the flat
belt. Please contact Forbo Movement
Systems prior to taking any of theaforementioned countermeasures.

Flat belt slips(no/reduced performance/
power trans­mission)

Belt tension too low

Increase belt tension(observe recommended elongation
at fitting)If there is no improvement or
the recommended elongation at
fitting is exceeded, please contact
Forbo Movement Systems

Flat belt too long. Flat belt
length incorrectly measured(wrong order length)

Correctly measure required flat belt
length (see Chapter 5.2), shorten
flat belt if possible or replace

When ordering, the inner lengthof the flat belt is crucial

Insufficient belt tension,strong creep

Increase belt tension(observe recommended
elongation at fitting)If there is no improvement or
the recommended elongation at
fitting is exceeded, please contact
Forbo Movement Systems

Bending frequency too highReduce speed

If there is no improvement pleasecontact Forbo Movement Systems

Belt bearing overload,
relaxation of flat belt notcomplete

Let flat belt run slowly with no load;
if necessary, tension in two stages(see Chapter 6.3)

The relaxation of Siegling Extremultus
flat belts can take several operating
hours or more. If it is not possible totension the flat belt in two stages,
design the machinery bearings for the
initial value of the shaft load. Pleasecontact Forbo Movement Systems

Overload of belt bearings due
to polyamide tension member
drying out

In constantly dry climate:
Relax belt slightly

Polyamide is susceptible tochanges in ambient temperatureand humidity. Should you encounterany problems please contact
Forbo Movement Systems

Flat belt gets
excessively hot

Pulleys get
excessively hot

In variable climate:
Use flat belt with different
tension member material
Narrowing

Flat belt overstretched(elongation at fitting too high)

112 Extremultus Compendium · 01/2019

Change flat belt, reduce belt tension(observe recommended elongation
at fitting)

Please contact Forbo Movement
Systems regarding the calculationof the flat belt

11.5 Wear

Description of the problem

Cause of the problem

Countermeasure

Comment/recommendation

Wear on underside offlat belt

Friction during
normal operation

No countermeasurenecessary/possible

Friction/wear on the underside of
the flat belt is normal. The flat belt is
to be considered a wearing part

Belt tension too low or power
to be transmitted is too high(excessive slip)

Increase belt tension(observe recommended
elongation at fitting)

The flat belt is partially or entirely
operated in the slippage area.
If there is no improvement or
the recommended elongation at
fitting is exceeded, please contact
Forbo Movement Systems

Pulleys are dirty

Clean pulleys

Performing regular maintenance on
the machinery results in a longer
lifetime for the flat belts

Grooves or damage tothe pulleys

Lathe pulleys,
avoid grooves

Damage to the surface of the pulley
can damage the underside of theflat belt

Pulleys are not
perfectly aligned

Align pulleys parallel andflush to one another

Misaligned pulleys(especially crowned pulleys) result insignificantly higher loads and shorter
belt life cycles

Pulleys haveincorrect geometry

Design pulleys ascrowned or cylindrical

For information on crown heights
see Chapter 8.1

Flat belt touches
machinery parts

Check machinery for stalled shafts,
bearings and pulleys as well as for
sharp edges that may come into
contact with the flat belt

Due to the high relative speeds
between a flat belt in operation
and a stalled part of the machinery,such contact results in quick failureof the flat belt

Leather surface hardened,coarse abrasion

Roughen leather surface
with a wire brush and apply
Extremultus spray paste

Leather is a natural product that loses
its special properties without regularcare. The leather surface should be
soft, greasy and dull. See Chapter 6.4
for care instructions

Wear on underside offlat belt with fine red dust

Longitudinal vibrations

Replace the flat belt with anotherbelt with a suitable tension member

Longitudinal vibrations can only
be influenced by the use of aflat belt with a different tension
member material. Please contact
Forbo Movement Systems

Wear on top face offlat belt

Wear during the course of
normal operation frommedium to be transported(e.g. paper)No countermeasure necessary/
possible

Wear on the top face of the flat belt
during the course of transport isnormal. The flat belt is to be con­sidered a wearing partSee “Wear on the underside of
the flat belt”

See “Wear on the underside of
the flat belt”

See “Wear on the underside of
the flat belt”

113 Extremultus Compendium · 01/2019

11.5 Wear

Description of the problem

Cause of the problem

Countermeasure

Comment/recommendation

Wear on the edge(s) of
the flat belt

Flat belt touches
machinery parts

Align pulleys with one another,check the crowning of the pulley,
check machinery for stalled shafts,
bearings and pulleys as well as for
sharp edges that may come into
contact with the flat belt

Due to the high relative speeds
between a flat belt in operation
and a stalled part of the machinery,such contact results in quick failureof the flat belt

Flat belt touches
flanged pulley

Align pulleys, check crowning ofpulleys, dismantle flanged pulleys

Avoid flanged pulleys in general.
However, if flanged pulleys areunavoidable, see notes in Chapter 8.1

Edges not sawn
(polyamide line in gang saw
with shifter)

Replace flat belt. Mention sawnedges when re-ordering.

When operated with a shifter,
sawn edges on flat belts in thepolyamide line have proven tohave longer service lives thancut edges.

Pulley diameter smaller thanrecommended minimum

Replace pulley with a larger one or
select Siegling Extremultus productwith corresponding minimum
pulley diameter

Siegling Extremultus flat belts are
manufactured from several layers ina “sandwich design”. When the pulleys
are too small, the tensions between
the layers are so big that it leads toseparations between the layers

External mechanical influences,peeling the surface

Replace flat belt and checkmachinery for stalled shafts,
bearings and pulleys as well as
for sharp edges that may comeinto contact with the flat belt

Due to the high relative speeds
between a flat belt in operation
and a stalled part of the machinery,such contact results in quick failureof the flat belt

Bonding strength between
the layers too low

Replace flat belt

If there is ply separation on a Siegling
Extremultus flat belt and the mini­
mum pulley diameter has been met,
please contact Forbo Movement
Systems immediately

Ply separation(delamination) in splice area

Overloaded endless spliceor faulty endless splice see
Chapter 11.2

see Chapter 11.2

see Chapter 11.2

Flat belt gets longitudinalgrooves and/or breaks in thelongitudinal direction

Pulley(s) designed as conicalcylindrical or crowned withsharp peak in the middle

Use crowned or
cylindrical pulleys

For information regarding therecommended geometries ofpulleys see Chapter 8.1

Belt runs up on
flanged pulley

Align pulleys, check crowning ofpulleys, dismantle flanged pulleys

Avoid flanged pulleys in general.
However, if flanged pulleys areunavoidable, see notes in Chapter 8.1

Ply separation(delamination)

114 Extremultus Compendium · 01/2019

11.6 Changes in properties

Description of the problem

Cause of the problem

Countermeasure

Comment/recommendation

Cross crackingsin the rubber surface

Ageing of
the rubber material

No countermeasurenecessary/possible

Cross crackings are a familiar
phenomenon with ageing
rubber material subject toconstant dynamic loadDegradation

Influence ofincompatible media

Examine temperatures andchemicals used and use suitable/
resistant flat belts

Forbo Movement Systems has
a variety of Siegling Extremultus
flat belts in its range that all havedifferent resistances to tempera­ture and/or chemicals. Should you
encounter any problems pleasecontact Forbo Movement Systems

Brittleness, discoloration

Effect of UV rays

Protect flat belts fromdirect UV rays or use
UV-resistant flat belts

Depending on the durationand intensity of the exposure,plastics chemically degrade(age) under the influence of UVA,
B and C rays (sunlight).
The UV rays cause brittlenessand color change (discoloration)in the material.
Forbo Movement Systems has
special products in its range foruse in applications in which theflat belts are exposed to increased
UV rays. Should you encounterany problems please contact
Forbo Movement Systems.

Shaft load/transmissible
power decreases

Influence of
ambient temperatureand humidity

Control climatic conditions,observe specifications for theflat belts, if necessary replace
the flat belt with another one
with a suitable tension member

Polyamide is susceptible tochanges in ambient temperatureand humidity. Should you encounterany problems please contact
Forbo Movement Systems

115 Extremultus Compendium · 01/2019

116 Extremultus Compendium · 01/201912	GlossarY

117 Extremultus Compendium · 01/2019

12 Glossary

A

Term

Explanation

Abrasion

Abrasion, also known as wear, refers to the loss of material on the surface of materials during use.
Abrasion is caused by mechanical stress (e.g. friction). Depending on the material and surface properties,
particles (dust) are released from the surfaces in contact (e.g. flat belts and pulleys).

Antistatic

Property of a component that enables it to discharge electrostatic charges in a targeted manner to prevent
sudden discharging. Antistatic Siegling Extremultus flat belts are also fitted with conductive components.
The resistance (RDi as per ISO 21178) is under 3 · 108 Ω.

AramideHigh-strength tension member material with high E-modulus. It is used in Siegling Extremultus flat belts inthe form of cords (truly endless flat belts) or as yarn in mixed fabrics together with polyester yarn.

Arc length

Length of the flat belt in contact with the pulley by way of the arc of contact.

Arc of contact

The contact area, in angular degrees, in which the flat belt encompasses the pulley.

B B_Rex

Forbo Movement Systems software used to design belt drives and select suitable Siegling Extremultus flat belts.

Basic elongation at fitting

Elongation value used when fitting the flat belt in order to transmit the required effective pull without
taking the centrifugal force into consideration.

Belt construction

Structure of the flat belt. Please see Chapter 2.2 for more information.

Belt edge processing

Coating/sealing the belt edge/flat belt edge, generally using the coating material.
Please see Chapter 7.4 for more information.

Belt tension

The tension in the flat belt required for force-fit power transmission. The required belt tension is set byfitting the flat belt at a defined elongation at fitting.

Bending frequency

Number of bends made by a flat belt per unit of time. Example: If a belt completes a full revolution overtwo pulleys within one second, the bending frequency is 2 1/s = 2 Hz.

Butt splice

Type of splice used for some Siegling Extremultus flat belts in the polyurethane line. The ends of the flat belts aremelted together on the face and joined. Please see Chapter 7.2 for more information.

C Centrifugal force

The centrifugal force is a force that “pulls” the flat belt on the pulley towards the outside, reducing the shaft load. It is,however, a pseudo force (not a real force) due to inertia. Opposed to this force is the centripetal force (real force).
The centrifugal force is not to be ignored, especially when it comes to high speeds.

Climate resistance

Climate resistance refers to the ability of a Siegling Extremultus flat belt to reliably transmit the necessary forces evenin varying climatic conditions (e.g. relative humidity).

Cord

See Truly endless flat belt

Creep

Creep refers to how the elastic behavior of the flat belt material compensates for the differences in force andelongation in the belt strands (F1 and F2) caused by the effective pull FU. During normal operation flat belts shouldbe operated in this slip area.

Cross crackings

A phenomenon that occurs when dynamically stressed rubber ages.

Crown

See Crowning

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Term
Crowning

D DampingE

Explanation
Curvature of the pulley faces enabling the flat belt to track in a centered position.
Please see Chapter 8.1 for more information.
Describes the loss in amplitude of a vibration over time. The greater the damping of the flat belt,
the faster the vibrations are reduced following sudden or periodic excitation.

Dead tensioning

A phenomenon that can occur when installing new flat belts and tensioning them in many small stages.
The physical properties of the flat belt or tension member are changed to such an extent that it is no longer
possible to guarantee reliable power transmission. Please see Chapter 6.3 for more information.

Direction of movement

The installation direction of the Siegling Extremultus flat belt recommended by Forbo Movement Systems.
The direction of movement or installation direction can be crucial when it comes to preventing an opening inthe splice, especially for flat belts featuring a wedge splice.

Drag Belts

Siegling Extremultus flat belts developed specifically for drag belt conveyors. Both the top face and underside fea­
ture a low-friction textile coating with special electrostatic properties. Please see Chapter 2.9 for more information.

Drive pulley

The pulley on the motor or turbine that is driven and thereby transfers effective pull to the flat belt.

Driven pulley

The pulley on the generator or working machine to which the flat belt transfers the effective pull or
torque of the drive pulley.

Effective pull

The force exerted on the flat belt during power transmission at a given power and speed.
Please see Chapter 2.6 for more information.

Elastomers

Synthetic materials that are malleable yet resistant to deformation (e.g. rubber). Elastomers consist of wide-mesh,cross-linked polymers. The wide meshing allows the material to stretch under tensile loading.

Elastic Food Tapes

Specially developed Siegling Extremultus flat belts for use in areas where hygiene is vital, such as the food industry.
Further information can be found in Chapter 2.9.

Electrostatics

The study of stationary electric charges, load distributions and bodies charged with electrical fields.
Differences in potential are created in flat belts due to the constant contact and separation of the flat belts
and the pulleys (triboelectric effect). These differences can cause damage if discharge is uncontrolled.

Elongation

A change in the length of the flat belt as a result of an external force acting upon it.

Elongation at fitting

In order to transmit power/force, the flat belt must be tight in the machinery. The elongation at fitting is expressed asa percentage the elongation, or the change in length of the flat belt, necessary to achieve the required tension.

E-modulus,
elasticity module

A material constant describing the relationship between the tensioning and the elongation of a material in the elastic
deformation area. The higher a material’s E-modulus, the more tensioning, or force per unit of surface area, is required
to elongate (change the length) 1% of the material, for example.

Endless belt

A flat belt with endless splicing as described in Chapter 7.2 (except for truly endless flat belts)

Endless splicing

Splice in the flat belt according to Chapter 7.2.

Extremultus Product Finder

Online tool to help find products quickly and easily (for Siegling Extremultus flat belts).
Please see Chapter 4.4 for more information.
Available at: www.forbo.com/movement/ > E-Tools

Extremultus spray paste

Cleaning agent for Siegling Extremultus Power Transmission Belts with leather coating. Item number: 880026.

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12 Glossary

F

Term

Explanation

FabricA threading system crossing warp threads (lengthways) and weft threads (crossways) at right angles. Used as
the tension member in a variety of Siegling Extremultus flat belts. Please see Chapter 2.2 for more information.

Fabrication

Fabrication refers to cutting the belt to length and width as well as preparing and creating the splice for the
Siegling Extremultus flat belt. Depending on customer needs, fabrication can include some or all points.

Fastener, mechanical

Special fastener for some Siegling Extremultus flat belts. Wire clamps or hinges are pressed into the ends ofthe flat belt and then connected with a wire or pin. Please see Chapter 7.2 for more information.

Flanged pulley

A pulley with an extra one or two “walls” on the pulley edges. Please see Chapter 8.1 for more information.

Flash StarTM

Siegling Extremultus product with HC+ classification. See Highly Conductive (HC/HC+)

Folder Gluer Belts

A Siegling Extremultus flat belt specially developed for use in box-folding machines. The top face and often
the underside feature coating materials with a high level of grip and high abrasion resistance.
Please see Chapter 2.9 for more information.

Food safe

Siegling Extremultus flat belts that comply with certain criteria (e.g. FDA or EU), allowing them to be used in
the food industry.

Force peak

A short-term increase in the load on the flat belt (e.g. during start/stop operation).

Friction coefficient

The friction coefficient µ is a measurement of the friction force compared to the contact pressure. The friction
coefficient depends on the materials and the texture. In this case, the materials and surfaces of the flat belts(underside) and the pulleys are crucial

Full load

Machinery generally has three different operating modes: No load, partial load and full load. Full load describes theoperating mode in which maximum power transmission occurs.

G Grip StarTM

H Heating clamp/device
Highly Conductive (HC/HC+)

Siegling Extremultus product with a thermoplastic high or medium grip coating (coating material R). Grip StarTM
products boast all the advantages of rubber without its typical ageing effects like brittleness and cross crackings.
Device used to create a Z-splice, wedge splice, butt splice or overlap splice.
Property of a component that enables it to discharge electrostatic charges in a targeted manner to prevent sudden
discharging. Siegling Extremultus flat belts are equipped with conductive components when assembled.
HC: Antistatic properties must be present and there must be conductivity on the surface in a longitudinal direction(resistance ROB as per ISO 21178 under 3*108 Ω).
HC+: HC properties must be present on the top face and underside and there must be conductivity all the way
through the belt (resistance RD as per ISO 21178 under 109 Ω).
Siegling Extremultus products with the HC+ property bear the Flash StarTM label.

Holding time

Time that the heating temperature must be applied to the flat belt or the heating device in order to create a reliable
Z-splice, wedge splice, butt splice or overlap splice.

I

Initial value of the shaft load

Shaft load prior to relaxation of the flat belt. Please see Chapter 6.3 for more information.

L

Live Roller Belts

A Siegling Extremultus flat belt specially developed for use in driven roller conveyors. They feature high abrasion
resistance and low flexing action. Please see Chapter 2.9 for more information.

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TermLongitudinal vibrations

M Machine Tapes

Non-visible vibrations of the flat belt or the entire machinery in a longitudinal direction.
Please see Chapter 9.8 for more information.
Specially developed Siegling Extremultus flat belts used for conveying, distributing, positioning andother tasks on the production line. Please see Chapter 2.9 for more information.

Minimum pulley diameterA minimum pulley diameter is approved for all Siegling Extremultus flat belts. Using pulleys withthis approved diameter or greater eliminates the risk of damaging the flat belt as a result of excessive
compression or elongation during returns.

Mixed fabricFabric in which the warp and weft threads are made of different materials(e.g. aramide warp threads and polyester weft threads).

Moment of inertia

The moment of inertia indicates the resistance of a rigid body to a change in its rotational movement arounda given axis and thus depends on the mass distribution in relation to the axis of rotation. For large, two-pulley drives,
e.g. in hydroelectric power plants, the moments of inertia of the driving and driven side are required to calculate
the longitudinal eigenfrequency of the machinery.

N No load

Machinery generally has three different operating modes: No load, partial load and full load.
No load describes the operating mode in which there is no transmission of power/force.

Nomenclature

Nomenclature is the naming of the Siegling Extremultus flat belts. Each name provides a unique identification basedon the materials used, properties and textures (e.g. GG 30E-30 NSTR/NSTR black).

Nominal effective pull

The nominal effective pull indicates the effective pull that can be transmitted by a flat belt with optimal elongation
at fitting and optimal slip.

O Operating factor

P

Explanation

The operating factor c2 is a safety factor by which the effective pull to be transmitted is increased, due to unevenload and/or force impact during use.

Operating noise

Operating noise is the noise created when the flat belt is in dynamic use, in other words when it is running. Some­times unusual operating noises can indicate a defect or error. More information on this topic is given in Chapter 11.3.

Overlap splice

Type of splice for Siegling Extremultus flat belts from the polyurethane line. The ends of the flat belts are placed one
on top of the other, overlapped by 2 mm and then melted together. Please see Chapter 7.2 for more information.

Order length

The length required when ordering and manufacturing flat belts. Chapter 5.2 describes how to determine the orderlength.

Partial load

Machinery generally has three different operating modes: No load, partial load and full load. Partial load describes
the operating mode between no load (no power transmission) and full load (maximum power transmission)

Plastic

Materials with good technical properties consisting mainly of macromolecules. Plastics can be divided into groups ofthermoplasts, duroplasts and elastomers.

Polyamide

A synthetic, semicrystalline thermoplastic material featuring outstanding strength and resilience. Polyamide
boasts good chemical resistance to organic solvents and a relatively high melting temperature. However,this plastic is susceptible to changes in temperature and humidity. When used in Siegling Extremultus flat belts
it is usually in the form of highly orientated sheets.

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12 Glossary

TermPolyester

Polyester is a synthetic, thermoplastic material used in fabric tension members for Siegling Extremultus flat belts.
The polyester fibers used are hard-wearing and feature high elongation at break.

Polyurethane

Polyurethane is a plastic or synthetic resin made from the polyaddition reaction of dioles/polyoles and poly­
isocyanates. Depending on the degree of cross-linking and variable tightness of the knitting, the polyurethane
can be a duroplast, a thermoplastic or an elastomer. Thermoplastic polyurethane is used in the Siegling Extremultus
flat belts.

Power

Physical variable calculated using the force to be transmitted and the speed of the flat belt or the torque to betransmitted and the speed.

Power Transmission Belts

Siegling Extremultus developed flat belts to transfer power between the driving machine element (e.g. motor) andthe driven machine element (e.g. flywheel), especially for the transmission of high power levels.
Please see Chapter 2.9 for more information.

Product Finder

Online tool to help find products quickly and easily (for Siegling Extremultus flat belts).
Please see Chapter 4.4 for more information.
Available at: www.forbo.com/movement/ > E-Tools

PulleyRotationally symmetrical machine element upon which the flat belt is placed in a belt drive. The force-fit
transmission of power takes place on the contact surface between the pulley and the flat belt.

R Reference force

S

Explanation

The reference force is the result of the effective pull to be transmitted, multiplied by the operating factor c2.

Relaxation

The typical behavior of plastics in dynamic applications. In belt operation it means that the tension member“slackens” as a result of the “setting”. This process can be recognized by the reduction in the shaft load within
the first hours of the flat belt operation. Please see Chapter 6.3 for more detailed information.

Remaining elongation

The portion of the elongation at fitting that does not recede after the flat belt relaxes or is removed.

Rho value (ρ)

The Rho value (ρ) is calculated from the quotient of the effective pull and the surface in contact with the pulley. It
refers to the capability of a tension member to transmit an effective pull.

RubberViscoelastic material (vulcanized rubber) belonging to the elastomer group.

Running-in behavior

See Relaxation

Running-in ratio

The running-in ratio cinitial describes the relationship between the initial value of the shaft load andthe steady value. By multiplying the running-in ratio by the static shaft load Fws you get the initialshaft load acting on the bearings of the machinery directly following tensioning (prior to relaxation).

Shaft load

The load exerted on the shafts and bearings of the pulleys by the elongation at fitting and thus by
the tension of the flat belt. The shaft load is essential to the maximum transferable power.
Please see Chapter 2.6 for more information.

Sheet

Highly orientated polyamide in the form of a sheet to be used as a tension member for flat belts withhigh power transmission. More information in Chapter 2.2

Shifter, shifter roller

A device used to move flat belts (Power Transmission Belts) in a lateral direction during operation.
This device is used primarily in chip drives. The shifter roller, which is either fixed or on roller bearings,
comes into contact with the edge of the flat belt.

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Term

T

Explanation

Slack side of the belt

The slack side of the belt is the part of the flat belt that is not pulled by the drive pulley.
During operation there can be significantly less force there than on the tight side of the belt.

Slip

Refers to the difference in speeds of the mechanical elements in frictional contact with one another,
expressed as a percentage. With belt drives, slip occurs between the flat belt and the pulleys. There are
two types: creep (in normal operation) and slippage (overload).

Slippage

Unlike creep, the elastic behavior of the flat belt material can no longer fully compensate for the differences inforce and elongation in the belt strands (F1 and F2) caused by the effective pull FU in this slip area. The flat belt slides
off the pulley and should not be operated in this slip area.

Splicing

See Endless splicing

Splicing instructions

Instructions for creating an endless splice

Spring constant

The relationship between the displacement of a spring or elastic component (e.g. flat belt) and the force necessary todisplace it. The spring constant depends on the material and only applies to the elastic area of the materials.

Standard climate

For conditioning and testing plastics, DIN EN ISO 291 states that the standard climate in non-tropical countries isa climate in which the air temperature is 23 °C/+73 °F and the relative humidity is 50 %, while for tropical countries it is
27 °C/+81 °F and 65 %.

Steady roller

Roller used to steady a vibrating (“flapping”) belt strand in order to change the freely vibrating length.

Steady state value of the
shaft load

Shaft load following relaxation of the flat belt. Please see Chapter 6.3 for more information.

Stiffness, bending stiffness

The resistance of the flat belt to elastic deformation through bending when going over the pulleys.

Take-up range

The range available to the tensioning station for take-up when tensioning the flat belts.

Temperature stability

Temperature stability is the ability of a Siegling Extremultus flat belt to reliably transmit the necessary forces, even at
higher temperatures.

Tangential Belts

Specially developed Siegling Extremultus Flat Belts for use as spindle drives in spinning machines and twisters.
These flat belts feature particularly equal thickness along the entire length of the flat belt, even in the area ofthe splice, minimizing fluctuations in speed on the spindles. Please see Chapter 2.9 for more information.

TensionMechanical tension is the force per surface unit which acts in an imaginary section through a body(e.g. the cross section of the flat belt).

Tension member

The part of the flat belt responsible for the strength of the flat belt and thus for absorbing the forces acting on
the flat belt during operation. More information in Chapter 2.2

Tensioning station

Device on the machinery/conveyor that applies force when tensioning the flat belt.

TextureTexture describes the nature of the surface of the Siegling Extremultus flat belts. This includes fine textured surface(FSTR), normal textured surface (NSTR), coarse textured surface (GSTR), inverted pyramid texture (NP), smooth (GL),smoothed (SM), fabric surface (FBRC), leather surface (LTHR) and high performance (HP). Please see Chapter 2.2 formore information.

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12 Glossary

Term

Explanation

Thermoplastic

Plastics that becomes pliable within a certain temperature range (thermoplastic). This process can be repeated atwill provided the material is not thermally destroyed as a result of overheating. Due to the behavior of this material
it is also possible to melt the thermoplastic material and weld it. This effect is used when creating endless splices on
Siegling Extremultus flat belts with thermoplastic tension members.

Tight side of the belt

The tight side of the belt is the part of the flat belt that is pulled by the drive pulley. It is where the highest forces
occur on the flat belt during operation.

Top face

The side of the flat belt that does not come into contact with the surface of the drive pulley.
Previously also known as the functional side.

Traction,transport capacity

The traction or transport capacity refers to the ability of a coating and pattern of a Siegling
Extremultus flat belt to reliably convey a product (e.g. food in a cutting machine or cardboard in a folder gluer
machine).

Transmission capacity

see Rho value (ρ)

Transmission ratio

The transmission ratio i expresses the relationship of the speeds (and thus also the diameter of the pulleys) between
the driving and driven side.
i=

Transversal vibrations

Visible vibrations of the flat belt or tight side of the belt and/or slack side of the belt running vertical to the directionof movement (flat belt is “flapping”). Please see Chapter 9.8 for more information.

Triboelectric effect

An effect that describes the charging (build-up of differences in potential) of different materials through frequentrubbing together and separating. The actual quantity of the charge separation from the triboelectric effect depends
on factors such as temperature, surface quality, electrical conductivity, water absorption and the position of thematerials in the triboelectric series (electron affinity).

Truly endless flat belt

Flat belts featuring a cord tension member. They are coated and wound around two cylinders in the shape of a helix.
Please see Chapter 2.2 for more information.

U Underside
W Wear

Z

n1
d
= 2
n2
d1

The side of the flat belt that comes into direct contact with the surface of the drive pulley.
Previously also known as the running side.
See Abrasion

Wedge splice

DA type of splice in which the ends of the Siegling Extremultus flat belts are prepared in the shape of a wedge,
placed on top of one another and joined. An adhesive process is used to create the splice. Please see Chapter 7.2
for more information.

Whistling

A high-frequency noise emitted by a flat belt during power transmission. The transmission ratio is generally
above 5 : 1.

Width-based
nominal effective pull

The width-based nominal effective pull indicates the effective pull that can be transmitted at optimal elongation at
fitting and optimal slip per 1 mm width of the flat belt.

Z-splice

Type of splice for Siegling Extremultus flat belts from the polyester, aramide and polyurethane lines. The ends ofthe flat belts are punched using a Z-shaped punch, placed together and then melted together. Please see Chapter 7.2
for more information.

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13 Legal Notes

Because our products are used in so many applications andbecause of the individual factors involved, our operating
instructions, details and information on the suitability anduse of the products are only general guidelines and do not
absolve the ordering party from carrying out checks andtests themselves. When we provide technical support on
the application, the ordering party bears the risk of themachinery functioning properly.

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127 Extremultus Compendium · 01/2019

Siegling – total belting solutions
Committed staff, quality oriented organization and­production processes ensure the constantly high standardsof our products and services. The Forbo Siegling Quality
Management System is ­certified in accordance with ISO 9001.

Forbo Siegling service – anytime, anywhere
The Forbo Siegling Group employs more than 2,500 people.
Our products are manufactured in ten production facilities
across the world. You can find companies and agencies withwarehouses and workshops in over 80 countries.
Forbo Siegling service points are located in more than
300 places worldwide.

Forbo Siegling GmbH
Lilienthalstrasse 6/8, D-30179 HannoverPhone +49 511 6704 0
www.forbo-siegling.com, siegling@forbo.com

01/19 · GB · Reproduction of text or parts thereof only with our approval. Subject to change.

Ref. no. 333-2

In addition to product quality, environ­­mental protection is
an important corporate goal. Early on we also intro­duced anenvironmental management system, certified in accordancewith ISO 14001.