29. Install torque wrench, 0 to 50 ft. lb. scale, if avail-
28. Install torque wrench adapter bar, as shown in Fig.
able, and check rotating torque or rolling resistance
183. The adapter bar can be fabricated locally to
of wheel hub [Fig. 185). Rotating torque when using
specifications outlined in Fig. 184. Bar illustrated will
new bearings should be between 15 and 20 ft. Ibs.
accommodate wheel hubs with planetary bolt circle
On used bearings rotating torque should be between
diameters of 12, 16, 19, and 23 inches.
6 and 12 ft. lbs.
CAUTION: Make certain wheel brake is in complete
release position and that it is not dragging on brake
drum.
30. If rotating torque is not to specifications given above,
remove adapter bar and tighten or loosen inner nut
until rotating torque is within specifications. After
tightening or loosening nut as required, rap wheel
hub several times with plastic or rawhide faced mallet
while rotating hub to seat bearings. Recheck rotating
torque as indicated in step 29.
Second (Optional) Method
31. Attach heavy string or cord to one of wheel studs
on hub and wrap cord around wheel hub several
times attaching pound pull scale to end of cord as
shown in Fig. 186. Tighten inner nut until rotating
torque measured on pull scale is between 21 and 28
lbs. for new bearings and between 9 and 17 llbs. for
used bearings.
NOTE: Bearing preload rotating torque, using a
pound pull scale, is figured by multiplying the radius
(distance from center of wheel to outside diameter of
wheel hub) by the reading on the pull scale and
dividing by 12 to arrive at ft. lbs. of torque. For ex-
ample: Wheel hub radius of 8-5/16 inches times 24
[ 52]
