Handrail drive system conversion

In a factory prefabricated drive system conversion unit for the handrail of an existing escalator, the drive system conversion unit includes a channel member adapted to be fixedly connected to an existing escalator structure, with a rotatable friction wheel being mounted between the channels and driven via a chain drive, having a plurality of pressing rollers, and a lever-operated tensioning device, with a set of cluster rollers, having a plurality of rollers, being mounted on a cluster roller base plate arranged on each side of the friction wheel, and also including a handrail turn around with a clamped roller chain having a plurality of both roller and chain links, as well as end pieces and intermediate guide members. Directionless cluster roller bases as well as directionless channels can also be utilized to simplify and speed up the conversion operation.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The subject invention pertains to a factory or offsite prefabricated drive 
conversion unit for the technical renovation of an existing escalator, 
with which, during the local modification work, the old handrail drive and 
its peripheral parts are replaced without changing the existing basic 
structure of the escalator. 
2. Discussion of the Background of the Invention and Material Information 
The handrail drive of an escalator is a technically demanding assembly. Its 
main task or object consists of the gentle guiding and tensioning as well 
as synchronous driving, relative to the stair movement, of the handrail. 
For the care of the handrail as well as for achieving the longest possible 
service life, the frictional forces, specifically produced by the drive 
unit, should not be excessive due to the danger of crushing or 
deformation, and the bending or deflection angles, due to the accompanying 
overload of the handrail edges, should not be too tight or narrow. In 
addition, the operation thereof should occur with the use of small tension 
forces, which in turn increases the degree of effectiveness of the drive 
and which contributes to the care or protection of the entire system. Old, 
existing handrail drive systems generally cannot meet the noted 
requirements and show, even after a relatively short service time, 
corresponding wear patterns. With an otherwise generally good operating 
condition of an escalator, it is therefore worthwhile to replace the 
handrail drive unit with a conversion or exchange construction which, at 
the same time, permits the upgrading thereof to new standards and 
requirements. 
Generally, two different drive methods or principles are utilized, one 
pertaining to the pressing of the handrail, with a partial envelopment, 
onto a large friction wheel, the other pertaining to the passage of the 
handrail through a plurality of linearly arranged friction and control 
roller pairs which also frictionally drive the handrail. 
The first-noted principle permits that, in addition to the handrail drive, 
the clamping device can be arranged within the same arrangement, which 
makes the addition of a second peripherally placed tensioning assembly 
superfluous. 
U.S. Pat. No. 3,651,919 to Vollmer describes and shows a handrail drive of 
the previously noted type. The lower part of the escalator utilizes a 
friction wheel which is enveloped by the handrail over an angle of about 
90.degree. and is pressed thereagainst by a tensioned roller chain. 
Located on each side of the driving wheel, in order to maintain the angle 
of envelopment, are fixedly attached turn around or return elements, each 
utilizing three rollers. An additional device, arranged at the upper 
portion of the escalator, is utilized for the tensioning of the handrail. 
The turn around elements of this device bend the handrail strongly 
backwards and the separate tensioning device additionally adds to the cost 
of the drive. It is obvious that this handrail drive can be improved via 
an exchange or conversion unit which utilizes the advantages of a modern, 
technical drive. 
The firm of John P. SPRIGGS, Home Elevators Inc., Roswell, Ga., U.S.A., is 
marketing a handrail drive exchange or conversion unit, U.S. Pat. No. 
5,427,221, which includes, in a common carrier unit, a friction wheel with 
a pressing device having turn around and guide rollers on both sides 
thereof. Therein, the handrail, both before and after the pressing device, 
runs over but a single roller, so that the handrail suffers from high wear 
due to the severe deviation thereof. In addition, the outer guidance 
causes frictional markings or grooves in the turn around rollers. 
SUMMARY OF THE INVENTION 
It is therefore the task or object of this invention to produce a 
conversion or exchange handrail drive which avoids the previously noted 
disadvantages; can be utilized without requiring changes in the existing 
basic structure; and which drives and guides the handrail without slip and 
with the greatest possible care. 
This task or object is achieved by the subject invention via the features 
set forth in the appended claims. 
Specifically, in this invention, in a factory prefabricated drive system 
conversion unit for the handrail of an existing escalator, the drive 
system conversion unit includes a channel member adapted to be fixedly 
mechanically connected to an existing escalator structure; a rotatable 
friction wheel mounted between the channels and driven via a chain drive; 
a roller chain, having a plurality of pressing rollers, and a 
lever-operated tensioning device; a set of cluster rollers, having a 
plurality of rollers, mounted on a cluster roller base plate arranged on 
each side of the friction wheel; and a handrail turn around, secured at 
each end of the existing escalator structure, including a clamped roller 
chain having a plurality of both roller and chain links, as well as end 
pieces and intermediate guide members. 
In a further embodiment of the drive system conversion unit of this 
invention, the set of cluster rollers, mounted on each side of the 
friction wheel, are pivotable about a pivot axis and affixable via 
retention screws passing through elongated apertures in the cluster roll 
base plates, and the pivot axis is coincident with the axis of a cluster 
roll, of the plurality of cluster rollers, most closely adjacent to the 
axis of the friction wheel. 
In another embodiment of the drive system conversion unit of this 
invention, the set of cluster rollers, mounted on each side of the 
friction wheel, is each retained by means of a threaded stud, adjusting 
nuts, and an angle support plate. 
In an additional embodiment of the drive system conversion unit of this 
invention, the plurality of the rollers of the set of cluster rollers, 
mounted on each side of the friction wheel, is arranged along a curved 
path, whose radius is one of the same and larger than the radius of the 
friction wheel. 
In still a further embodiment of the drive system conversion unit of this 
invention, the plurality of the rollers of the set of cluster rollers, 
mounted on each side of the friction wheel, further include horizontal 
stud-mounted guide rollers, rotatably retained on a guide support for the 
lateral guidance of the handrail. 
A yet another embodiment of this invention pertains to factory 
prefabricated conversion drive unit for the technical upgrading of an 
already existing escalator via which, in an on-site conversion step, the 
existing old handrail drive unit and its peripheral parts are replaced 
without changing the basic existing structure of the escalator, the 
conversion drive unit including a directionless cluster roller base, via 
the use of which left hand as well as right hand cluster roller sets are 
produced. 
A still an additional embodiment of this invention pertains to a factory 
prefabricated conversion drive unit for the technical upgrading of an 
existing escalator via which, in an on-site conversion step, the existing 
old handrail drive unit and its peripheral parts are replaced without 
changing the basic existing structure of the escalator, the conversion 
drive unit including a channel member wherein the channel member is 
provided with all of the apertures, recesses and attachment points which 
are necessary for the assembly of both left hand and right hand drive 
conversion units. 
The advantages of the present invention are that the entire prefabricated 
conversion or exchange unit can be installed without costly adaptive work; 
that the handrail drive occurs with the highest possible care; and that, 
at the same time, conformity with existing standards and requirements can 
be achieved. 
Additional advantages reside in the fact that the latest developments, 
regarding materials technology and construction technology, are utilized.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With respect to the drawings it is to be understood that only enough of the 
construction of the invention and the surrounding environment in which the 
invention is employed have been depicted therein, in order to simplify the 
illustrations, as needed for those skilled in the art to readily 
understand the underlying principles and concepts of the invention. 
In FIG. 1, numeral 1 denominates a friction wheel which is enveloped over 
about 90.degree. by a handrail 2 and pressed thereagainst by means of a 
tensioned roller chain 3. Friction wheel 1 is driven by a chain drive 5 
via a coaxially affixed sprocket 4. Roller chain 3 is retained in constant 
mechanical tension, at a predetermined tension, via a tensioning device 9 
comprised of a ratio lever, threaded set bolt, clamping nuts and a spring. 
Arranged on each side of friction wheel 1 is a left hand and right hand set 
7, 8, respectively, of cluster rollers 16, arranged along a curved line, 
over which handrail 2 is received or guided as it leaves friction wheel 1. 
Friction wheel 1 and roller group sets 7, 8, as well as the mounting 
support for roller chain 3 and its tensioning device 9, are all mounted on 
a common channel member 6, with channel member 6 in turn being connected 
with the existing structure of the escalator via adaptor portions 10 and a 
support bracket 11. 
FIG. 2 shows the details of right hand cluster roller set 8. Mounted on the 
upper periphery of a cluster roller base or plate 12, in short, uniform 
spacings, are seven rollers 16, arranged along a curved line. The entire 
cluster roller set 8 can be pivoted about a pivot point 17 coincident with 
the axis of the left-most first roller 16, with this pivoting being 
bounded within the region of the elongated holes 18 and 19 that are 
located at about the center of cluster roller base 12. Retention screws 
20, affixed to channel member 6 and extending through elongated holes 18 
and 19, block or retain cluster roller base 12 in an adjusted position. As 
a set-up or adjustment aid, a threaded stud 21, threaded in channel member 
6 and provided with adjusting nuts 22, is provided on the back side of 
cluster roll base plate 12 and extends parallel to elongated holes 18 and 
19. Cluster roller base plate 12 is additionally braced or retained on 
adjusting nuts 22, above threaded stud 21, via an angle support 33 welded 
on the rear face or side of plate 12 and can, upon the loosening of 
retention screws 20, be adjusted to a specific height position. 
Horizontal guide rollers 13, each affixed on a stud 14 of guide support 15, 
are provided between the second and third as well as the fourth and fifth 
rollers 16. Guide rollers 13, in the form of a rolling element bearing 
such as a ball bearing, are enclosed by the profile of handrail 2 and 
thereby provide the side or lateral guidance thereof solely via rolling 
friction. 
Roller chain 3, shown in FIG. 3, is comprised of chain members or links 23 
and rollers 34, with left and right end members or links being denominated 
by numerals 24 and 25, respectively. 
FIG. 4 shows the turn around 27 of handrail 2 at a stair or escalator end. 
FIG. 5 illustrates the individual parts of turn around or return 27, which 
takes the form of a roller chain having chain links 28, rollers 29, end 
pieces or terminal ends 31 and 32 as well as guide members 30, the latter 
being inserted and clamped into the U-shaped, semicircularly extending 
canals or channels of the balustrade constructions at the stair or 
escalator ends. Freely rotatable rollers 29 permit a low friction turn 
around of handrail 2, with guide members 30 serving for the lateral 
guiding of handrail 2. 
The function of the entire apparatus should, in principle, be evident from 
the drawing figures. A special feature is the gentle guidance of the 
handrail as it exits from the friction wheel 1. Rollers 16 are arranged 
along a circular path which, in comparison to friction wheel 1, has the 
same or a larger radius, wherein friction wheel 1 already has, considering 
the space available, the largest possible radius. In order to best 
possibly avoid the excessive bending or contortion of handrail 2, upon the 
resetting of the handrail tension, not the entire cluster roller sets 7 
and 8 are adjusted, in parallel, height-wise, but are rather pivoted 
upwardly about pivot axis 18, only as far as is necessary to obtain the 
desired tension, and are then again fixedly secured. This tension 
generally should not be high and any resetting thereof should only avoid 
excessive slack during the return of handrail 2. The length of handrail 2 
is so measured that in the new condition, rail 2 does not yet touch the 
last roller 16 of left hand cluster roller set 7 and/or right hand cluster 
roller set 8. Such touching occurs only after the first or second 
resetting or adjustment thereof. As soon as, after several adjustments, 
there is a bending or contortion as handrail 2 emanates from one of 
cluster roller sets 7 or 8, wherein the radius of the bend is smaller than 
that of the roll curvature, then the handrail length must be shortened. 
The adjustment of one of cluster roller sets 7 or 8 is eased in that 
cluster roller sets 7 or 8, upon the loosening of retention screws 20, 
have their angle support 33 resting upon adjusting nuts 22 of threaded 
stud 21 and thus do not suddenly slide vertically downward. Any further 
adjustment can then be made by merely upwardly turning adjusting screws 22 
and then successively tightening retention screws 20 in elongated or 
slotted holes or apertures 18 and 19. FIG. 1 illustrates the extreme upper 
settings of cluster roller sets 7 and 8. The thin or dotted lines 
additionally show the extreme lower settings. 
The drive of handrail 2, only via friction, requires a relatively high 
pressing force thereof onto friction wheel 1. Therefore, the tension of 
roller chain 3 must be set very high and maintained for pressing rollers 
34. For this purpose, roller chain 3 has its right terminal piece attached 
to channel member 6 and its left terminal piece 24 guided or retained by a 
lever tensioning device 9. Since the tensioning device lever ratio is, for 
example, 5:1, the right lever end can, via the use of the threaded rod, 
compression spring and nut, be adjusted with very little effort so as to 
produce a sufficiently large tensioning force. 
The construction of the device or apparatus of this invention is 
furthermore so designed that the installation is both short and problem 
free. This requires a construction which requires no adaptation work 
relative to existing structure 26. Adapter members 10 and a support 
bracket 11 serve as intermediate members. By means of these intermediate 
members the installation of the conversion or replacement drive is made 
possible without requiring changes at the existing structure of differing 
types of escalators. Even in a worst case situation only additional 
intermediate members need be utilized and even these can be prefabricated, 
thus necessitating no increased time requirements for the rebuilding of 
the escalator. In order to achieve the highest possible universal 
utilization of the conversion drive system, channel member or plate 6 is 
provided with several additional apertures in order to avoid drilling at 
the construction site. Thus it is possible, even with the use of simple 
clamping brackets to achieve a solid or rigid attachment of the conversion 
drive system at an existing structure 26. 
The drive or actuation of this device is accomplished by means of a 
sprocket 36 mounted on an existing drive shaft via a chain drive 5 having 
a chain tensioning roller 35. The transmission via chain drive 5 allows, 
upon the consideration of minimal of slip in the handrail drive, the 
highest possible synchronization with the movement of the steps. Long and 
trouble-free operation of the conversion drive system is assured in that 
all rotating bearings take the form of sealed rolling element bearings. 
In a further embodiment of the conversion drive system and of channel 6, 
the latter can be so designed that a single design or embodiment can be 
utilized for both left and right hand sides of the escalator. Therefore, a 
neutral-sided or direction-less channel contains all of the holes, 
recesses and attachment points so as to permit, via an offsite or factory 
preassembly, the production of a conversion drive system for the use in 
both left and right hand side applications. Thus, the drive systems or 
assemblies for the left and right hand sides of the escalator are 
identical in design but of allochiral or mirror image construction. 
In addition, cluster roller base or plate 12 can be so constructed that 
with but a single design variation, both left and right hand cluster 
roller sets 7 and 8, respectively, can be produced. In this design, angle 
support 33 is no longer welded onto the rear face or side of plate 12, but 
rather the horizontal leg portion thereof is slid through a stamped slot, 
with the vertical leg portion being attached, via screws that extend 
through pre-stamped apertures, at preassembly. Prefabricated cluster 
roller bases of this type, since they are thus no longer bulky, can be 
stored more compactly and at double density, as well as being easier to 
manufacture. 
While there are shown and described present preferred embodiments of the 
invention, it is to be distinctly understood that the invention is not 
limited thereto, but may be otherwise variously embodied and practiced 
within the scope of the following claims and the reasonably equivalent 
structures thereto. Further, the invention illustratively disclosed herein 
may be practiced in the absence of any element which is not specifically 
disclosed herein.