CAT PRECISION SEALS®

Design Information
Load Deflection
The typical load/deflection graph for aDuo-ConeTM seal has a relatively flat slope,which illustrates that these seals work
satisfactorily over a wide range of operating
gaps. HDDF seals have different load
characteristics than Duo-Cone Seals because of
their design and must operate in different ranges
to provide satisfactory performance. Loaddeflection characteristics vary by metal face seal
type, load ring material and seal group size. CatSeals application engineering should be
consulted for design assistance concerning
proper loading of metal face seals.
Pressure Velocity
Metal face seal performance capability is best
described by its Pressure-Velocity (PV) or load/speed rating. The face load required to keep themetal seal rings in contact is related to theallowable speed, as described by the following
chart. Many factors influence this relationship,including seal ring material, seal ring diameter,
operating temperature, lubricant viscosity,pressure differential across the load rings, andaction of centrifugal force on the load ring.

high rotational speeds or high ambient
temperatures. High speeds can produce hightemperatures which deteriorates lubricant andchanges the properties of the elastomer loadrings. Both cases can lead to adverse sealing or
failure of the seal group. Always consult Cat Seals
application engineering for design assistanceconcerning appropriate loads for a desired speed.
How Application Variables Affect Design Choices
The selection of the proper metal face seal iscontingent on a thorough application review.
Differences in operating conditions have asignificant impact on the optimum metal faceseal for your product. Shown in the table below
are some significant application variables andthe component of the metal face seal productthey affect.

146 mm
(5.75 in)
457 mm(18.00 in)
Face load

533 mm
(21.00 in)
Rotational Speed

In low speed applications or with light lubricants,
face pressures are generally increased toensure sealing ability. The same is true whenseals are exposed to high differential pressures
and/or large end play or deflections. Lower faceloads are specified for applications producing

Variable

Design Component

Speed

Metal Seal Ring MaterialInternal/External
Pressure

Metal Seal Ring Material
and Ramp Angle

External Operating
Environment

Metal Seal Ring andElastomer Load Ring Material

Temperature

Elastomer Load Ring
Material

Available Space

Metal Face Seal TypeEnd PlayMetal Seal Type and Seal
Ramp Angle

Cat Seals Application Engineering
The engineers of Caterpillar can analyze yoursealing requirements and recommend the metal
face seal/elastomer combination that will best
meet your needs. Cat Seals can work with yourengineers to help design the application andprovide electronic drawings to aid in your design.
You need only complete the application datasheet and provide drawings of the area
containing the seals.

© 2014 Caterpillar • All Rights Reserved • Printed in USA
CAT, CATERPILLAR, BUILT FOR IT, their respective logos, “Caterpillar Yellow,” the “Power Edge”trade dress as well as
corporate and product identity used herein, are trademarks of Caterpillar and may not be used without permission.

Design Information
Seal Wear
Cast metal face seals by design automaticallycompensate for wear. The mating faces form acontact band approximately 0.5 to 1.0 mm (0.02to 0.04 in) wide that retains the oil lubricant andseals out all foreign material. As wear occurs,
the contact band will widen slightly and migrate
inward until the inside diameter is reached. As
depicted in the figure below, over time thecontact band of the cast seals migrate down thespherical radius as wear occurs.
Contact BandNewContact Band
Partially Worn

Formed seals are more flexible than the cast rings
they replace and, as a result, produce a wear
pattern different than cast ring designs. Typically,
formed seals wear in an axial rather than radial
direction, as depicted below, due to their increasedflexibility.
Wear Lip in these two areas
makes it necessary to
install a new seal.

Location ofWear Lip

Seal Service LifeAll seal life expectancies are application specific.
Because of the many differences in machine
applications, environmental conditions,maintenance and other factors that have adirect effect on the seal, it is difficult toestimate expected life.

© 2014 Caterpillar • All Rights Reserved • Printed in USA
CAT, CATERPILLAR, BUILT FOR IT, their respective logos, “Caterpillar Yellow,” the “Power Edge”trade dress as well as
corporate and product identity used herein, are trademarks of Caterpillar and may not be used without permission.