After disassembly, thoroughly wash all parts of the gearbox in kerosene, blow with compressed air and inspect

Gearbox housing. External inspection reveal cracks, chips, breaks of lugs and fastening ears, thread condition in the holes, absence of burrs and burrs on the sealing surfaces.

Crankcase that has cracks, chips and kinks, replace. Eliminate minor faults.

Gears. There should be no chips or nicks on the teeth.

The lateral surface of the teeth should not have any signs of chipping and crushing; there should be no burrs on the end surfaces of the gears.

Seating surfaces must be free of damage and wear that disturbs the alignment of parts.

Synchronizer gear rims should not have tooth destruction and electric rivets.

The gear of the first gear of a partially synchronized gearbox must not have burrs that extend beyond the height of the splines on the side of engagement of the second gear.

Clean up the burrs.

The splines of this gear, mating with the mounting surfaces of the secondary shaft, should not have metal sags at the ends on the side of the inner diameter.

If they are available, during assembly, connect such a gear to the secondary shaft so that the landing is carried out through other splines that have not previously participated in the landing. Replace bad parts.

The input shaft must not have damage on the teeth of the fourth gear engagement ring.

There must be no chipping on the rolling surface of a roller bearing.

The splines of the shaft must not have nicks (the clutch disc must move freely along them).

Replace the worn shaft.

The output shaft must not have scuffing and deep scratches on the seating surfaces under the gears of the first, second and third gears, chipped splines and spalling on the rolling surface of the roller bearing. Replace the worn shaft.

Intermediate shaft must not have any damage to threads and teeth (crushing, chipping). Worn shaft, shaft gear unit (on a synchronized gearbox) replace.

Partially synchronized gearbox synchronizer assembly and selection

Fig. 13. Completion and selection of parts of the synchronizer of the gearbox, partially synchronized: 1 - clutch; 2 - hub.

Note. With mutual movement of parts by 14 mm, misalignments in the splines, measured at points A1 and A2 on R40, should not exceed 0.35 mm (as shown)


Check the connection of the coupling 1 (see Fig. 13 and 37) of the synchronizer with the hub 2 and in case of significant mutual displacements exceeding twice those indicated in the figures in the direction perpendicular to the axis of the part, replace the coupling kit with the hub.

Select a new kit according to the instructions in fig. 13 and 37.

Replace the synchronizer clutch if the teeth are damaged or worn.

Replace the synchronizer blocking rings if the gap between the end of the ring and the end of the gear engagement ring is less than 0.3 mm, and also if the ring is deformed.

Bearingsshould not have damage to cages, cracks and chips of rings, chipping of ball raceways, as well as noticeable radial and axial play.

The bearing cages must not be damaged. Replace worn bearings.

The side cover of the gearbox must not have chips, cracks, damage to the sealing surfaces and holes for installing plugs.

Stemsshould be straight and not have chipping in the area of ​​operation of locks and latches.

The lock pin of the stem of the third, fourth gears must move freely in the hole without falling out of it.

The length of the pin, taking into account wear, must not be less than 9.8 mm. Replace worn parts.

Control dimensions of gear shift forks of a partially synchronized gearbox

Fig. 14. Control dimensions of the shift forks of the gearbox, partially synchronized: A - fork of I, II gears; B - fork III, IV gears

Control dimensions of gear shift forks of a synchronized gearbox

Fig. 15. Control dimensions of the shift forks of a synchronized gearbox: A - fork of I and II gears; B - fork III and IV gears

Forks must not be cracked or bent.

Position of the legsforks with respect to the switching groove must correspond to the dimensions shown in fig. 14 and 15.

If the wear of the shifting grooves reaches 1 mm, replace the fork.

Miscellaneous parts

Thrust washers of gears and keys must not be scored.

Oil deflectors must be of the correct shape and not interfere with adjacent parts.

The cup spring of the intermediate shaft rear bearing bolt must not be cracked.

The sealing rubber ring of the intermediate shaft front bearing cover must not have breaks or cracks.

The input shaft cover must not have cracks, breaks or damage to the working and seating surfaces.

The trunnions in the gear lever support must not wobble in their sockets.

The rubber seal of the shift lever must not have breaks or through cracks.

Replace any worn parts.