Moving handrail drive belt tensioning device

A spring loaded tensioning assembly is mounted on the truss of a moving walkway or escalator to apply pressure and tension to a moving handrail drive belt. The assembly includes a roller which is biased against the inside surface of the drive belt to urge the drive belt against the inside surface of the handrail. The tensioning assembly is an adjunct to the original equipment drive belt tensioner and can be retrofitted onto existing equipment in the field to extend the service life of the drive belt.

DESCRIPTION 
1. Technical Field 
This invention relates to a moving handrail drive belt tensioner, and more 
particularly to an auxiliary drive belt tensioner which can be retrofitted 
onto existing equipment in the field. 
2. Background Art 
The moving handrail of an escalator or moving walkway is driven by a drive 
belt that engages the inside surface of the handrail and frictionally 
applies a driving force to the handrail. The handrail is forced by the 
drive belt against a support roller bow which provides the backup force 
for the drive belt. The drive assembly is mounted on the people mover 
truss along the return path of travel of the handrail. The drive belt is 
reeved over a drive roller and a tension roller, the latter of which is 
spring-biased so as to stretch the belt thereby applying a constant 
tension thereto. One drawback which has arisen with the aforesaid drive 
system is excessive drive belt wear, which requires frequent replacement 
of the drive belts. 
DISCLOSURE OF THE INVENTION 
This invention relates to a drive belt tensioning assembly which can be 
retrofitted onto an existing escalator or moving walkway in the field, and 
which lessens the problem of drive belt wear encountered in the prior art 
system. The belt tensioning assembly of this invention applies a 
tensioning pressure directly to the drive belt from the inside of the 
drive belt loop. The drive belt is thus forced against the handrail after 
the handrail has encountered the support roller bow. The tensioning 
assembly of this invention includes a mounting bracket which can be 
secured to the people mover truss by two bolts which are already disposed 
on the truss. A threaded rod is secured to a yoke or fork in which a 
pressure roller is journaled. The threaded rod is slidably mounted on the 
bracket, and is spring loaded against a stop surface on the bracket so as 
to spring load the pressure roller against the inside surface of the drive 
belt along the arc of the support roller bow. The outer surface of the 
presser roller has circumferential grooves which match ribs found on the 
inner surface of the drive belt. 
It is therefore an object of this invention to provide a moving handrail 
drive belt tensioner that can apply a pressing force on the drive belt 
which presses the drive belt against the handrail. 
It is another object of this invention to provide a drive belt tensioner of 
the character described which presses against the inner side of the drive 
belt loop to force the drive belt against the handrail. 
It is a further object of this invention to provide a drive belt tensioner 
of the character described which can be retrofitted onto an existing 
escalator or moving walkway in the field. 
It is an additional object of this invention to provide a drive belt 
tensioner of the character described which utilizes a spring force to 
press the tensioner against the drive belt. 
These and other objects and advantages of the invention will become more 
readily apparent from the following detailed description of a preferred 
embodiment thereof when taken in conjunction with the accompanying 
drawings, in which:

BEST MODE FOR CARRYING OUT THE INVENTION 
Referring now to the drawings, FIG. 1 shows a handrail drive assembly which 
includes a drive belt 2 reeved about a powered roller 4 and a tensioning 
roller 6. The powered roller 4 will typically be driven by the main step 
drive sprocket (not shown) in the escalator or moving walkway. The 
tensioning roller 6 is journaled on a tension carriage 8 mounted on the 
people mover truss 10 and biased in a drive belt-stretching direction by a 
spring 12. The drive belt 2 contacts the inner surface of the handrail 14 
as the latter moves along an arcuate path of travel defined by a support 
roller bow assembly 16. The roller bow assembly 16 includes a curved 
elongated bracket 18 which is secured to the truss, and on which are 
journaled a plurality of support or backup rollers 20 which contact the 
outer or exposed surface of the handrail 14. The inner surface of the 
drive belt 2 which contacts the rollers 4 and 6 is ribbed so as to 
increase friction between the powered roller 4 and the drive belt 2. 
The tensioning device of this invention is denoted generally by the numeral 
22, and is mounted on two existing bolts 24 and 25 located on the truss 
inside of the loop of the drive belt 2. The tensioner 22 includes a 
pressure roller 26 which is movably mounted on a bracket 28. In the 
embodiment shown in FIG. 1, the handrail 14 moves in the direction of the 
arrow A, and the pressure roller 26 is located to the handrail entry side 
of the roller bow 16. 
FIGS. 2--4 show details of the tension device 22. As noted in FIG. 2, the 
bracket 28 has a hole 30 at one end for receiving the truss bolt 24, and 
an elongated slot 32 at the other end for receiving the truss bolt 25. The 
slot 32 allows some flexibility as to the exact locations of the bolts 24 
and 25. A guide 34 having a through passage 36 projects from the side of 
the bracket 28, and an elongated slot 38 is formed to one side of the ear 
34 in general alignment with the passage 36. As seen in FIGS. 3 and 4, a 
threaded rod 40 carries a yoke 42 at one end thereof, and extends through 
the ear passage 36. A nut assembly 44 threaded onto the rod 40 secures the 
yoke 42 in place, and a coil spring 46 seats against the ear 34 and 
against a second nut assembly 48 threaded onto the rod 40 at the end 
thereof distal of the yoke 42. The pressure roller 26 is journaled on the 
yoke 42, and includes an axle assembly 50 which extends through the slot 
38. The roller 26, yoke 42 and rod 40 can thus be pulled to the left as 
viewed in FIGS. 3 and 4 thereby causing the spring 46 to compress and urge 
the assembly back toward the right, as viewed in FIGS. 3 and 4. As seen in 
FIG. 4, the outer circumferential surface of the roller 26 is grooved as 
at 52 so as to compliment the ribbed inner surface of the drive belt 2. 
As noted in FIG. 1, when the assembly 22 is mounted on the truss bolts 24 
and 25, the roller 26 can be pulled to the left so that it will compress 
the spring 46 and thus wedge the roller 26 against the handrail 14 as the 
latter moves up the curved path defined by the support roller bow 16. The 
roller 26 is thus forced against the moving drive belt 2 to in turn press 
the driVe belt 2 against the handrail 14. The roller 26 also increases the 
tension on the portion of the drive belt 2 disposed between the roller 26 
and the roller 6, thereby increasing the pressure exerted by that section 
of the drive belt 2 on the handrail 14. 
It will be readily appreciated that the tensioning assembly of this 
invention is of simple yet rugged design, and can be attached to existing 
people movers in the field. The assembly will directly press the handrail 
drive belt against the handrail, and will also create an additional degree 
of tension in the portion of the drive belt interposed between the 
pressure roller and the downstream drive belt tension roller. The result 
of adding the tensioning assembly of this invention is increased drive 
belt life. 
Since many changes and variations of the disclosed embodiment of the 
invention may be made without departing from the inventive concept, it is 
not intended to limit the invention otherwise than as required by the 
appended claims.