37
6.
Belt Tension Check
The automatic belt-tensioning device is designed to maintain proper tension throughout belt life. It is recommended,
however, that belt tension be checked periodically and confirmed to be within tension requirements. If belt tension is
not within the limits described, contact an authorized Quincy Distributor for service. On 3V belt sections, new belt
tension should read between 6.5 - 7.5 pounds deflection force and the run-in belt tension should have a reading
between 4-5 pounds deflection force for 3V belt sections. On 5V belt sections, new belt tension should read 10
pounds deflection force and the run-in belt tension should have a reading of 8 pounds deflection force. Without
exception, the most important factor in the successful operation of a V-belt drive is proper belt tensioning. Too little
tension results in slippage, causing rapid belt and sheave wear. Too much tension can result in excessive stress on
belts, bearings and shafts.
After installing new belts operate the unit for two hours to run-in the belts. To measure belt tension, refer to
illustration on page 39.
1. Measure the span length (t)
2. Position the lower of the two o-rings using either of the following methods:
a) On the scale reading “Deflection Inches”, set the o-ring to show a deflection equal to 1/64” per inch of span
length (t).
b) On the scale reading “Inches of Span Length”, set the o-ring to show a deflection equal to the inches of
measured span length (t). Read scales at the bottom edge of o-ring. Leave the upper o-ring in maximum up
position.
Always rotate pulleys a minimum of 2 revolutions before taking belt tension measurements. At center of span (t)
apply force, with Tension Tester perpendicular to the span, large enough to deflect one belt on the drive until the
bottom edge of the lower o-ring is even with the tops of the remaining belts. A straight edge across the belt tops will
assure accuracy of positioning. Use belt tension gauge P/N 142645 to measure the deflection force halfway between
the pulleys as shown.
Find amount of deflection force on upper scale of Tension Tester. The sliding rubber o-ring slides down scale as
tool compresses – stays down for accurate reading of pound pressure. Read at top edge of ring. (Slide ring up
before re-using.)
Compare deflection force with range of forces stated above. If less than minimum recommended deflection force,
belts should be tightened. If more than the maximum recommended deflection force, drive is tighter than necessary.
Check tension of all belts on the drive as described above.
Check the ride height. All the belts in each set must ride at the same height in the pulley groove within 0.030” total
of each other.
Recheck for pulley misalignment and correct as necessary.
Operate the drive a few minutes to seat the belts in the sheave grooves. Observe the operation of the drive during
start-up and full load operation (highest load conditions). A slight bowing of the slack side of the drive indicates
adequate tension. Excessive bowing or slippage indicates insufficient tension. If the slack side remains taut during
the highest load, the drive is too tight.
Check and assure the motor base plate is level when belts are at initial tension. If motor base is level, belt tensioning
is complete. If not level refer to motor base instructions on page 38.
NOTE:
If problems are noted with belts, refer to Section VIII for troubleshooting procedures.
To Next Page
Loading...
Need help?
General
