Power shift transmission – Range gearbox


DISASSEMBLY

Power shift range transmission showing component parts end their relative positions.

1.Spacer, 2.Shim, 3.Bearing, 4.Input shaft, 5.Bearing, 6.Slotted nut, 7.Nut, 8.End plate, 9.Needle roller bearing, 10 Sliding collar gear, 11.Sliding collar, 12.Bearing inner race, 13. Thrust washer, 14.Bearing inner race, 15.Third range gear, 16.Sliding collar, 17.First range gear, 18.Shim, 19.Pinion shaft, 20.Roll pin, 21.Washer, 22.Bearing, 23.Thrust washer, 24.Shim, 25.Spacer, 26.Bearing inner race, 27.Second range gear, 28.Needle roller bearing, 29.Reverse range gear, 30.Needle roller bearing, 31.Sliding collar gear, 32.Bearing inner nice, 33.Needle roller bearing, 34.Thrust washer, 35.Bearing, 36.Range housing, 37.Shim, 38.Bearing, 39.Idler shaft, 40.Bearing, 41.Second/reverse range shift rod, 42.Second/reverse shift fork, 43.Shift interlock ping, 44.Detent spring, 45.Detent ball, 46.First/third range shift rod, 47.First/third shift fork

Power shift transmission incorporates a three-speed range gearbox located directly behind the power shift unit. Except for removal of bevel pinion shaft (19), range gearbox components can be serviced after splitting the tractor and removing power shift unit. If removal of pinion shaft is required, range gearbox must be removed from tractor as follows:

Remove
- platform or cab (if so equipped). 
- fuel tanks. Support tractor with suitable stands, then remove rear wheels and final drive assemblies. 
- differential lock sleeve and spring from right side of rear axle housing.
- transmission cover and remote valve assembly. 
- pto assembly and pto drive shaft. Support rear axle housing with a hoist, remove mounting bolts securing axle housing to main frame and remove axle housing. 
- transmission mounting bolts and bushings. Attach lifting chain and hoist to transmission, then move transmission rearward   from   main   frame.   Mount transmission on a stand if available.
- nuts from transmission studs, then separate power shift unit from range gearbox. 
- spacer and sprag clutch from end plate bearing retainer. Drive roll pin (20) from pinion shaft (19). 
- locking nuts (6 and 7) noting that shaft has left-hand threads. 
- spacer (21) and bearing (22). 
- end cover mounting bolts, then lift end cover (8) from range housing (36).
- thrust washer (23), shims (24), spacer (25), second gear (27), needle roller bearings (9) and race (26) from pinion shaft. 
- second/reverse shift rod and collar (11) as an assembly. 
- gear (10), bearing (28) and race (12), reverse gear (29), thrust washer (13), third gear (15), bearings (30) and race (14), first/third shift rail assembly with collar (16) and sliding collar inner gear (31). Withdraw input shaft assembly (4) and idler shaft assembly (39). 
- first gear (17), bearing (33) and race (32) and thrust washer (34). Mark differential carrier bearing caps to ensure correct reassembly, then remove caps and differential assembly. 
- pinion shaft (19) and rear bearing (35) rearward from range housing.
- neutral start switch, rods and balls from housing. 
- shift interlock plug (43), detent ball (45) and spring (44).

REASSEMBLY

Inspect all gears, thrust washers and bearings for excessive wear or damage and renew as necessary. If renewal of input shaft (4) or idler gear (39) or their bearings is required, shaft end play must be set as outlined in following paragraph before reassembling transmission. If renewal of pinion shaft (19) or rear bearing is necessary, pinion shaft protrusion must be set before proceeding with reassembly.

IDLER SHAFT AND INPUT SHAFT END PLAY

Heat bearings to 120°C (250°F) maximum before installing on the shafts. 

Install
- spacer (1) and front bearing cups minus shims (2 and 37) into front end housing. Position idler shaft and input shaft assemblies into housing. 
- front housing. 
Remove the four housing mounting studs, if not already removed, and install four bolts in place of the studs. Tighten bolts to 95 N-m (70 ft.-lbs.) torque and rotate shafts to be sure bearings are seated.
Mount a dial indicator so probe contacts end of idler shaft through hole in front housing. Move shaft up and down and measure end play. Mount dial indicator so probe contacts end of input shaft. Move shaft up and down and measure end play.
Remove front end housing and remove front bearing cups using a suitable puller. 
- shims (2 and 37) in front housing as necessary to obtain 0.05-0.10 mm (0.002-0.004 inch) end play for each shaft. Reinstall bearing cups in front housing making sure they are properly seated. Remove idler shaft and input shaft from range housing.

PINION SHAFT ASSEMBLY

With pinion shaft protrusion set and pinion shaft installed in housing, reassemble range transmission as follows: 

Install
- thrust washer (34) on pinion shaft with oil grooves facing away from rear bearing. 
- first gear (17), bearing (33) and race (32). Position idler shaft and input shaft assemblies in housing. Position shift interlock plug (43) in housing bore so it is between shift rod holes in range housing.  
- gear (31) on pinion shaft. 
- sliding collar (16) and first/third shift rail assembly. Use tool to depress detent ball and spring as shift rail is inserted into housing bore.
- third gear (15), bearings (30) and race (14). 
- thrust washer (13) with oil grooves facing away from third gear. 
- reverse gear (29), bearing (28) and race (12). 
- sliding collar gear (10), sliding collar (11) and second/reverse shift rail assembly. Use special tool to depress detent ball and spring as shift rail is pushed into housing bore. 
- second gear (27), bearing (9) and race (26). 
- spacer (25) with larger outside diameter against second gear.
- shims (24) removed during disassembly plus an additional 0.25 mm (0.010 inch) thickness of shims to assure pinion shaft end play. 
- thrust washer (23) with flat side of washer against shims. 
- end housing (8) with front  bearing cup and tighten mounting bolts to 40 N-m (30 ft.-lbs.) torque. 
- pinion shaft bearing (22), washer (21) and nut (7). Tighten nut to 271 N-m (200 ft.-lbs.) torque. Mount a dial indicator so probe contacts end of pinion shaft and measure shaft end play. Remove pinion shaft bearing retaining nut and front housing. Subtract shims from shim pack (24) equal to measured end play plus an additional 0.05 mm (0.002 inch) to provide bearing setting within specified range of zero end play to 0.05 mm (0.002 inch) preload.

With correct thickness shims installed, reinstall front housing, bearing, washer and retaining nut. Tighten nut to 271 N-m (200 ft.-lbs.) torque. Install locknut (6) and tighten to 271 N- m (200 ft.-lbs,) torque, then back nut off to first slot and install roll pin (20).
Apply Loctite 270 to threads of studs, install studs and tighten to 95 Nm (70 ft.-lbs.) torque. Complete installation by reversing the removal procedure.