Page 33 - Goodyear2011PTMaintenanceManual

Synchronous Belts
INSTALLATION GUIDE
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If using a tension gauge, the defection scale is calibrated in
inches of span length. Check the force required to defect
the belt the proper amount. There is an O-ring to help
record the force. If the measured force is less than the
required defection force, lengthen the center distance. If
the measured force is greater than the required defection
force, shorten the center distance.
If using other means to apply force to the belt, adjust the
center distance so that the belt is defected 1/64" per inch
of span length when the proper force is applied. After the
belt is properly tensioned, lock down the center distance
adjustments and recheck the sprocket alignment. If
possible, run the drive for approximately 5 minutes with or
without load. Stop the drive and lock out the power source
and examine alignment, capscrew torque and belt tension
of the drive. Adjust the center distance to increase the belt
tension to the “New” Value in the Defection Force Tables.
Lock down the drive adjustments and recheck tension.
Recheck the belt tension, alignment, and capscrew torque
after eight hours of operation to ensure the drive has not
shifted.
The following few sections detail other issues that could
arise during Synchronous belt installation.
USING A FIXED CENTER DISTANCE
A fxed center distance drive has no adjustment for
tensioning or installing the belt. Due to the tolerances of
drive components, including sprocket, belt, and drive
geometry, a drive with a Fixed Center Distance is not
recommended as adequate belt tension cannot be
assured. Proper belt installation requires a minimum
center to center adjustment. Refer to belt installation for
center to center adjustment. In some cases, fxed center
drives cannot be avoided and should be used only with the
understanding that belt life will be reduced.
DESIGN FACTORS
To ensure proper belt selection, consult the appropriate
design manual for Eagle NRG,™ Blackhawk Pd,®
Falcon HTC,® or Hawk Pd.® Due to the high load
capacity of these belts, make sure that all of the drive
components are adequately designed. Consult sprocket
and other component manufacturers for design assistance
or if verifcation of application is needed.
BELT GUARDS
Belt guards ensure cleanliness and safety. Screened,
meshed, or grilled guards are preferable because they
allow for air circulation and heat escape.
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17 IDLERS
Use idlers either inside or outside of the belt, preferably outside.
Idlers often function as a tensioning mechanism when the drive
has a fxed center distance. When an idler is necessary, follow
several general rules:
Locate the idler on the slack side of the belt.
Small, inside idlers should be grooved (up to 40 teeth).
Outside idlers should be fat, not crowned.
Minimum idler diameter should be 4 inches on 8mm pitch drives
and 8 inches on 14mm pitch drives.
Hold idler arc of contact to a minimum.
Do not use spring loaded tensioners.
Lock idlers frmly in place to minimize movement or defection
during drive start-up and operation.
TEETH IN MESH
Sprockets with low belt angle of less than 60 degrees or less than
six Teeth in Mesh will not transmit the full rated load. Should drives
be designed using less than six Teeth in Mesh, the service life of the
belt will be reduced.
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