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Massey Ferguson 250 - Differential and bevel drive gear

MF 230, 235, 240, 245, 250 Tractors Repair Operations

Differential

Massey Ferguson 250 and Orchard model tractors are equipped with planetary final drive units located in outer end of rear axle housings. On all other models, the rear axle shaft splines directly into the differential side gears. All models may be equipped with a mechanically actuated jaw-type differential lock.

Remove, reinstall and overhaul - The ring gear and differential unit can be removed from differential housing after removing the rear axle housing assembly from left-hand side of Massey Ferguson 250 tractor. Disassemble the removed differential unit, first scribe alignment marks on both halves of differential case to ensure correct reassembly. Pull bearing cone off differential lock coupler cap, then remove cap screws retaining coupler cap. Remove coupler cam and separate differential case halves. Differential side gears, pinion gears and cross can now be removed. The main drive bevel ring gear is secured to differential case half with either special bolts and nuts or rivets. Note that ring gear is a press fit on case and may also be epoxy bonded to case if it has been previously serviced. Inspect all parts for scoring, chipping, wear or other damage and renew if necessary. Pinion gears and cross should be renewed as a set. Backlash between pinion gears and side gears should be 0.08-0.28 mm (0.003-0.011 inch). Reassemble differential, reverse the disassembly procedure while noting the following special instructions: If bevel ring gear was removed, use special epoxy bonding kit when reinstalling. Be sure to follow kit instructions and cure epoxy for correct time at specified temperature. Apply Loctite 262 to threads of ring gears retaining bolts and tighten evenly to 160 Nm (120 fl-lbs.) torque. Be sure to align differential case scribe marks, and tighten retaining cap screws to 108 Nm (80 ft.-lbs.) torque. To reinstall differential, reverse the removal procedure. If differential case halves and/or carrier bearings were renewed, bearing preload should be checked and adjusted as outlined in paragraph 159.

Carrier bearing preload - The differential carrier bearing preload is adjusted by installing correct thickness spacer shield, or shim depending on differential type, under right-hand carrier bearing cup. The recommended method of checking the preload adjustment is by use of Massey Ferguson special tool. If tool is not available, an alternate procedure (although not as accurate) can be used as follows: This adjustment procedure should be performed with bevel drive pinion gear removed to prevent interference with movement of differential. Install differential assembly and left-hand axle housing, or carrier bearing housing, depending on differential type. Install a 1.27 mm (0.050 inch) spacer shield, or several shims, and bearing cup into right-hand axle housing or carrier housing. A spacer shield thickness change is likely using this procedure. When shield is removed it Is usually distorted beyond reuse. Position axle housing or carrier housing (without gasket or O-ring) onto differential housing and install three or four equally spaced retaining cap screws. Tighten cap screws evenly until end play of differential is just removed. Rotate differential several turns to make certain that bearings are properly seated. Use a feeler gage to measure gap between axle housing and differential housing at several different locations. Preload will be correct when measured gap is 0.43-0.55 mm (0.017-0.022 inch) on models with drum brake axles, or 0.25-0.38 mm (0.010-0.015 inch) on models with disc brake axles. Remove axle housing or carrier housing and change spacer or shim thickness as necessary.

Differential lock

Operation - When the differential lock foot pedal is depressed, the axle half of coupler is forced inward to contact the differential case half of the coupler. If slippage is occurring at one wheel, depressing the pedal will cause the coupler dogs to lock the differential case to the right axle. The differential and both drive wheels then rotate together as a unit. As soon as contact is made by the coupler dogs, the pressure wlll keep the differential lock engaged and foot pedal may be released. When ground traction on both drive wheels again becomes equal, coupler dog contact pressure will be relieved and the coupler will automatically disengage.

Adjustment - On all except Orchard models and MF 250 models, differential lock coupler should be fully engaged when pedal clears tractor step plate by 12 mm (1/2 inch). If adjustment is required, loosen clamp screw and reposition pedal on actuating shaft. Retighten clamp screw when adjustment is complete. On Orchard models and MF 250 models, pedal should be against stop when released. If not against stop, loosen locknut and turn clevis until pedal arm just contacts stop. Tighten locknut after acljustment is complete.

Remove and reinstall - Remove the differential lock coupler halves, first drain Massey Ferguson 250 transmission and hydraulic reservoir, block up under diffet·ential housing and remove right fender and rear tire and wheel assembly. Remove right lower hitch link and disconnect right brake linkage. Support rear axle housing assembly in a hoist and remove retaining stud nuts, then slide right rear axle and housing as a unit away from differential housing. Remove bearing cone from coupling half. Remove the differential case retaining cap screws and lift off the coupling. When installing, tighten differential case cap screws to a torque of 108 Nm (80 ft.-lbs.). To remove axle half of coupler on models without planetary final drive, upbolt rear axle outer bearing retainer from axle housing and withdraw axle from housing; then lift out the coupler. Shoes will be free in fork with coupler removed. To service the actuating mechanism, remove the clamp bolt and withdraw actuating shaft from housing and pedal, then lift out the remaining actuating parts. Remove axle half of coupler on models with planetary final drive, remove spring pin securing shift fork to actuating shaft and the two countersunk screws secw·ing carrier plate to axle housing, then slide plate, fork and coupler carefully off end of drive axle. On all models, assemble by reversing the disassembly procedure and adjust after axle housing is reinstalled.

Main drive bevel gears

Remove and reinstall - The main drive bevel ring gear and bevel pinion gear must be renewed as a matched set. Remove bevel ring gear, first remove differential assembly. Ring gear retaining nuts are installed with thread locking compound, and removal will be easier using a slight amount.of heat on the nuts. Ring gear is a tight fit and may also be bonded to differential case with epoxy, so it will probably be necessary to press ring gear from differential case. Remove bevel pinion gear, first remove hydraulic lift cover. Remove axle housings and differential assembly if not previously removed. On Massey Ferguson 250 tractor equipped with independent pto, Multi-Power transmission or auxiliary hydraulics, split the tractor between differential housing and transmission housing. Remove pto side cover, disconnect hydraulic lines, remove pump support pins and remove hydraulic pump assembly and independent pto clutch unit out front of differential housing. On MF 250 models not equipped with independent pto, Multi-Power transmission or auxiliary hydraulics, it is not necessary to split the tractor to remove pinion shaft. Remove the coupler tube and pinion drive shaft. Remove side cover from left-hand side of housing and move pto driven gear forward on pto shaft splines. Remove ground speed pto drive gear from pinion shaft. On all models, remove cap screws attaching retainer to housing, then thread two of the cap screws into the tapped holes in retainer. Tighten the two cap screws evenly to force retainer with pinion as an assembly from housing bore. Check and adjust differential carrier bearing preload, If necessary, before reinstalling bevel pinion gear. When reinstalling bevel pinion gear, make certain that the locating pin is aligned before pressing retainer into place. Tighten retainer cap screws to 108 Nm (80 ft.-Ibs.) torque. Complete installation by reversing the removal procedure.

Overhaul - Disassemble bevel pinion gear, proceed as follows: If bearing adjusting nut is retained by a tab washer, unlock tabs and remove the nut. If bearing adjusting nut is retained by locking pins, it will be necessary to split the nut using a hammer and chisel to remove nut from the shaft. Be careful to avoid damaging threads of pinion when splitting the nut. On all models, bump the pinion shaft out of retainer after nut is removed. Examine all parts for wear or other damage and renew as necessary. Bearings and retainer are serviced as an assembly. When reassembling pinion gear, tighten nut to obtain pinion rolling torque of 2.25 Nm (20 in.-lbs.) to provide correct bearing preload. Secure nut by bending tabs of lock washer or by driving locking pins down both sides of one of the pinion splines. Be sure pins are flush with end of adjusting nut. When installing the ring gear, make certain that mating surfaces of ring gear and differential case are thoroughly clean and free from nicks or burrs. Apply special epoxy to both mating surfaces and cure for specified time following kit instructions. Apply Loctite 262 to threads of retaining nuts and tighten to 108 Nm (80 ft.-lbs.) torque.