gear and jackshaft gear at internals of (60 degrees
(38) If noise level remains the same, remove drive
around the hull gear.
wheel from drive axle housing.
(15) Insure that backlash is between 0.008 and 0.012
(39) Install drive wheel and bearings on spindle.
(40) Mount a dial indicator on the spindle.
(16) Using a dial indicator, check backlash at one of
(41) Check run out of bull gear face and inside
the bull gear retaining screws.
diameter of bull gear teeth. (fig. 3-75.)
(17) If backlash between bull gear and jackshaft gear
(42) Insure that run out on bull gear face does not
exceed 0.010 inch.
(18) Check that bull gear and jackshaft gear are
(43) Insure that run out on inside diameter of bull
properly lubricated according to LO 10-3930-620-12..
gear teeth does not exceed 0.005 inch.
(19) Insure that areas between the teeth of the bull
(44) If run out of bull gear face and inside diameter of
gear are filled with grease to approximately 3/4 to 7/8 the
bull gear teeth are within allowable limits. remove mast.
height of the teeth.
drain differential, and remove differential cover.
(20) Clean and check each bull gear tooth contact
(45) Operate drive motor and check noise level.
(46) Mount a dial indicator on differential carrier.
(21) Insure that contact pattern is located at the same
(47) Check backlash between ring and pinion gears
point on each tooth, of equal length, and that pitting or
at four positions (90 degrees apart).
peening is not present.
(48) Insure that backlash is between 0.005 and 0.010
(22) Operate drive train without the drive wheels
inch or as etched on pinion gear face.
installed and check noise level.
(49) If backlash setting is adjusted, check noise level.
(23) If noise is present, remove jackshaft and operate
(50) If noise level is not reduced after backlash
drive motor in forward and reverse gear.
setting is adjusted, reset backlash at several settings
(24) If noise is not present after performing step (23),
within the range.
inspect the differential side gear splines
(51) Set backlash at lowest noise level within the
and jackshaft splines.
(25) Loosen drive motor support bracket nuts.
(52) If noise level does not change after backlash
(26) Operate drive motor and check noise level while
adjustment, check ring and pinion gear tooth contact.
varying the amount of looseness of the bracket nuts.
(53) Apply a coat of red lead, white lead, or prussian
(27) Secure drive motor support bracket in position of
blue to ring gear teeth.
lowest noise level.
(54) Rotate ring gear slowly until a good tooth contact
(28) Loosen front drive axle mounting pad bolts.
pattern is made in ring gear tooth coating.
(29) Operate drive motor and check noise level.
(55) Adjust tooth contact pattern as indicated in figure
(30) If noise level remains the same, loosen rear
3-76 by shimming.
drive axle pad bolts.
(56) Recheck backlash if tooth contact pattern has
(31) If noise level is reduced, check flatness of axle
and frame mounting pads.
(57) Check clearance between pinion gear face and
(32) Check each mounting pad on drive axle and
frame for flatness and squareness.
(58) Insure that clearance is 0.156 -0.002 inch.
(33) Place a straight bar stock across drive axle pads
(59) Add or remove shims between drive motor
and check for parallelness.
mounting flange and differential carrier, as required.
(34) Insure that mounting pads are parallel with each
(para 3-47e (16) (a). )
other and on the same horizontal plane.
(60) Check noise level after shimming pinion gear.
(35) Repeat steps (32) through (34) for frame
(61) Remove carrier caps from carrier and lift
differential end bearings with differential from carrier.
(36) Check screws securing drive motor flange to
(62) Check differential end bearings for foreign
differential carrier and drive axle housing to carrier.
matter, uneven wear, or scoring.
(37) If any bolts require tightening, operate drive
(63) Check differential carrier bearing mount
motor and check for change in noise level.