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Synchronous Belts
Installation Guide
43
20. Multiple sprocket drives
Multiple sprocket drives typically have one DriveR and two or
more DriveN sprockets. In these cases, it is acceptable to size
the drive based on the most severely loaded shaft. This is
usually the DriveR shaft since the load of all the DriveN shafts
must be transmitted through one DriveR shaft. Sprockets with
a low belt wrap angle, less than 60 degrees and/or a low
number of teeth in mesh, less than six teeth, will not transmit
full rated load and service life of the belt will be reduced.
The number of teeth in mesh is equal to Belt Wrap in mm/Pitch
in mm. Backside idlers can be used to increase belt wrap
(see Table 17 on page 36). For detailed multiple sprocket
drive design, contact a drive design specialist at
Continental ContiTech.
21. Bearing loads
On many drives, bearing life is a concern. Reducing the bearing
load will increase bearing life. Bearing loads can be reduced in
the following ways:
Calculate the belt tension instead of using the belt tensioning
tables. The tables are general and may specify higher belt
tension than is necessary on some drives. Contact your
Distributor to assist in calculating actual belt tension
requirements for your drive.
Larger diameter sprockets will require less belt tension on any
given drive.
Always position the sprockets close to the bearings. This
positioning will reduce the effect of the “overhung” bearing
load. Be sure not to install a belt at less than the recommended
tension. A belt that is under-tensioned will have a reduced
service life.