Repair of bridges of the MAZ car

The central gearbox of the rear axle, after being removed from the car for repair, is disassembled on a workbench 500-600 mm high in the following sequence:

• - remove drive gear 5 (see Fig. 1) with bearings as an assembly;
• - remove the stoppers and unscrew the nuts 20 of the differential bearings, loosening the bolts securing the covers 21;
• - remove the covers of 21 differential bearings;

• - unscrew the nuts of the differential cup mounting bolts and disassemble the differential using dismantling bolts (remove satellites, side gears, thrust washers);
• - remove, if necessary, bearings 22 of the differential using a universal puller;
• - clamp the drive gear in a vise, the jaws of which are covered with soft metal pads, unscrew the nut and remove the flange 9 of the drive gear, cover 13 with the stuffing box;

- remove housing 15 with bearings; remove the inner race of the inner tapered bearing from the pinion shaft using a universal mandrel puller (fig. 2);

- if necessary, press the outer cages of the drive gear bearings out of the bearing housing using a puller (Fig. 3) without ring 6.

The disassembled parts of the central gearbox are washed and carefully inspected.

Check the condition of the working surfaces of the bearings: they should not have crumbled places, cracks, dents, peeling.

Rollers and separators should also not be destroyed or damaged.

Gear teeth should not have chips and breaks, cracks, chipping of the cementation layer, pitting. Nicks and burrs on the gear teeth must be removed and cleaned.

The wear of the teeth of bevel gears in thickness is characterized by the amount of backlash with properly adjusted gearing (along the contact patch).

The gap is measured with an indicator from the side of the large diameter.

If the noise of the gears of the central gearbox is increased, the value of the side clearance of 0.8-0.9 mm can serve as a basis for replacing the bevel gear pair.

If it is necessary to replace one of the gears, it is necessary to completely replace the driving and driven bevel gears, since at the factory they are matched in pairs according to the contact patch, side clearance and are marked with the same number.

When inspecting the details of the differential, pay attention to the condition of the surface of the necks of the cross, the holes and spherical surfaces of the satellites, the bearing surfaces of the side gears of the support washers and the end surfaces of the differential cups.

These surfaces must be free of burrs. In case of significant wear or loose fit of the bronze satellite bushing, it must be replaced.

Process the new bushing after pressing it into the satellite to a diameter of 32+0.05mm.

In case of significant wear of the bronze bearing washers of the side gears, the latter must be replaced.

The thickness of the new bronze washers is 1.5 mm. Differential cups, if it is necessary to replace one of them, are replaced as a set.

The gearbox housing is made of malleable cast iron КЧ 37-12.

The main defects in which the crankcase is restored is the wear of the holes for the crankcase of the bearings and the hole for the rear bearing of the drive gear shaft, damage to the threads for the nuts of the differential bearings.

When the hole for the crankcase of the drive gear shaft bearings is worn to a diameter of more than 150.10 mm, it is bored to a size of 156 + 0.08 mm to a depth of 44 + 0.1 mm.

The repair sleeve is pressed into the bored hole (Fig. 4) until it stops against the shoulder, ensuring an interference fit in the range of 0.08-0.12 mm and aligning the hole in the sleeve with the oil channel in the bearing housing.

The hole in the sleeve is bored to a diameter of 150 + 0.063 mm, the end of the sleeve is cut flush with the base metal and a chamfer of 2x30 ° is bored.

The hole for the rear bearing of the pinion shaft, worn out to a diameter of more than 90.07 mm, is restored by installing a repair sleeve.

The worn hole is bored on a lathe in a faceplate to a diameter of 96 + 0.07 mm to a depth of 22 + 0.1 mm.

Then press the repair sleeve until it stops against the collar, providing an interference in the range of 0.05–0.08 mm, and bore the hole in the sleeve to a diameter of 90 + 0.035 mm.

The end of the sleeve is cut flush with the base metal and a chamfer of 1.5x30 ° is bored.

If the thread for the adjusting nuts of the differential bearings is damaged, they bore: the damaged thread for the left bearing nut up to 135.9-02 mm to a depth of 21 mm, a chamfer 1.5x45 °, a groove 5 mm wide to 139 mm to a depth of 21 mm and cut repair thread M138x2 to exit into the groove.

If the thread for the nut of the right bearing is damaged, the following is bored: damaged thread up to 155.9 mm to a depth of 19 mm, a chamfer 1.5 x 45 °, a groove 5 mm wide to a diameter of 159 mm to a depth of 19 mm and a repair thread M158 x is cut 2 to exit the groove.

When repairing the gearbox housing, the following basic requirements for the relative position of the surfaces must be met:

• - the runout of the surface of the hole for the rear bearing of the drive gear shaft relative to the surface of the hole for the bearing housing is allowed no more than 0.05 mm;
• - runout of surfaces for differential bearings relative to each other is allowed no more than 0.05 mm;
• - the runout of the threaded surfaces for the adjusting nuts of the differential bearings relative to the surfaces of the holes for the differential bearings should not exceed 0.2 mm;
• - non-perpendicularity of the axis of the surfaces of the holes for the rear bearing and the crankcase of the bearings of the drive gear shaft relative to the surfaces of the holes for the differential bearings should not exceed 0.05 mm over a length of 100 mm;
• - the axis of the surfaces of the holes for the rear bearing and the crankcase of the drive gear shaft bearings must intersect with the axis of the surfaces of the holes for the differential bearings with a deviation of no more than 0.05 mm.

The bearing housing of the pinion shaft is made of malleable cast iron КЧ 37-12.

The crankcase is restored when the holes for the outer rings of the roller bearings of the drive gear shaft are worn and when the crankcase journal is worn.

If there are cracks and breaks, the crankcase is rejected.

When the hole for the outer ring of the front roller bearing is worn to a diameter of more than 130.0 mm, it is restored by installing a repair sleeve.

To do this, bore holes to a size of 136 + 0.08 mm to a depth of (32 ± 0.3) mm and make a chamfer 1 x 45 °.

Then, a repair sleeve is pressed into the hole. (fig. 5) until it stops against the jumper, providing an interference fit within 0.05–0.08 mm and aligning the holes in the bushing with the hole in the crankcase.

A hole with a diameter of 12 mm is drilled in the bushing through a hole in the bearing housing and a hole is bored in the pressed bushing to a diameter of 130-0.028-0.068 mm, chamfering 2x45˚

When the hole for the outer ring of the rear roller bearing is worn to a diameter of more than 130.0 mm, it is also restored by placing a repair sleeve (see Fig. 5) in the previously indicated sequence.

The runout of the surfaces of the holes for the outer rings of the roller bearings of the drive gear relative to each other should not exceed 0.05 mm.

The holes are machined on a lathe, ensuring installation on the landing neck of the crankcase. The seat neck, worn out to a diameter of less than 150.02 mm, is restored only by surfacing using a special technology.

The cups of the differential box are made of malleable cast iron КЧ 37-12.

The cups are restored: in case of scuffing, risks or uneven wear of the end under the washer of the axle gear; wear of the holes for the spikes of the cross; scoring, risks or wear of the spherical surface under the washers of the satellites; wear of the holes for the trunnion of the axle gear; wear of the necks under the bearings of the differential and for the right cup when the neck under the driven gear is worn.

Cups are rejected for cracks or breaks.

The left and right cups are structurally different from each other. Therefore, their repair for distinctive defects and sizes will be considered separately.

Left Cup

In case of risks, scoring or uneven wear of the end face of the bearing surface under the washer of the axle shaft gear to a size of less than 47.2 mm from the axis of the holes for the pincers of the differential cross to the bearing surface under the gear of the axle shaft, the end face is machined to remove burrs and signs of wear to one of the repair sizes shown in Table 1.

Surface roughness should be Rz20.

The supporting surface is machined in a faceplate on a lathe, based on the mating surface with the right cup.

It should be noted that in order to perform turning operations, the mating surfaces of the differential boxes are taken as the base for both cups of the differential box, and for the right cup, in addition, an additional base can be taken - a neck for a bevel driven gear, and only if eu whether there is a need to replace the gear.

Nominal and repair dimensions of the bearing surface for axle gear near the cup of the differential box (table 1)
Size	Distance from hole axes under spikes to the reference surface for axle gear, mm	Thickness support washer, mm
Rated 1st repair 2nd in 3rd .	46.5+0.1 46.7+0.1 46.9+0.1 47.1+0.1	1.5-0.1 1.7-0.1 1.9-0.1 2.1-0.1

The left and right cups of the differential box are rejected if the distance from the axes of the holes for the spikes of the cross to the bearing surface for the axle shaft gear is more than 47.2 mm.

In case of risks, scuffing or wear of the spherical surface under the washers of the satellites to a size of less than 134.36 mm, the spherical surface is bored to one of the repair sizes given in the table and the surface roughness Rz 20.

The left and right cups are rejected if the size is more than 134.36 mm.

The hole for the trunnion of the axle shaft gear, worn out to a size of more than 68.1 mm, is restored by setting the bushing.

To do this, the cup is installed in a faceplate, a hole is bored to Ø 73 + 0.06 mm to a depth of 27 mm and a surface roughness of 2.5 microns and a chamfer of 1x45 ° is removed.

Then, the repair sleeve is pressed (Fig. 6) into the bored hole, the hole in the sleeve is bored to Ø 68 + 0.06 mm and the roughness is 2.5 microns, the end of the sleeve is cut flush with the plane of the base metal, providing a roughness of 2.5 microns , bore a chamfer of 2x45 ° on the end of the bushing and cut a helical groove in the hole of the bushing in increments of 20 mm, with a depth of 1-0.5 mm, maintaining the groove radius (2 ± 0.5) mm.

When the neck for the differential bearing is worn down to a diameter of less than 75.01 mm, it is restored by expanding.

To do this, the cup is installed with the parting plane on the hydraulic press table and the neck is distributed up to Ø 75.2 mm with piercings (Fig. 7), the parameters of which are shown in Table 3.

Then, the neck surface is ground to Ø 75 mm and surface roughness of 1.25 µm, providing a fillet with a radius of 2-2.5 mm.

The holes for the spikes of the cross, worn out to a diameter of more than 25.08 mm, are reamed to the repair size or restored by surfacing.

Before surfacing, the holes in the left and right cups of the differential box are cleaned to a metallic sheen and the holes are welded alternately up to Ø 22 mm with an electrode Ø 4 mm.

Then, install the left cup on the studs of the right, at the same time aligning the holes with the locating pins, and screw the nuts onto the studs, tightening them to the full.

The assembled cups are fixed in the jig and holes up to Ø 23 mm are drilled on a radial drilling machine, two holes are drilled up to Ø 24.8 mm in a line and two holes are drilled up to Ø 25 + 0.023 mm in a line and surface roughness 2 .5 µm.

After that, the cups are disassembled and the sharp edges of the holes for the spikes of the cross are filed down with a chamfer of 0.5 x 45 °.

Before disassembling the cups, it is necessary to mark with paint their relative position, which is observed during assembly. Then the cups of the differential box are assembled.

Right Cup

The wear of the spherical surface under the pinion washers, the bearing surface under the side gear washer and the hole for the pin of the side gear of the right cup is restored similarly to the left cup.

If the journal for the differential bearing is worn down to a diameter of less than 100.01 mm, it is restored by vibro-arc surfacing up to 103 + 0.5 with wire Sv-Ø.8 1.6 mm at a rotational speed of the part of 2.5 min1, a wire feed speed of 1, 3 m/min and surfacing step 2.5 mm/rev, without cooling.

A similar method can be used to restore the neck under the bearing and at the left cup in cases where the expansion does not provide the required size.

The welded neck of the right cup is turned to 100.8 mm, providing a fillet radius (20.5) mm and a 2x30 ° chamfer at the end of the neck.

Then the neck is polished finally to a nominal 100 mm and a surface roughness of 1.25 microns.

Nominal and repair dimensions spherical surface for washers satellites at the cup of the differential box (table 2)
Size	Spherical diameter washer surfaces satellites, mm	Washer thickness satellites, mm
Rated 1st repair 2nd 3rd	133+0.16 133.4+0.16 133.8+0.16 134.2+0.16	1.5-0.1 1.7-0.1 1.9-0.1 2.1-0.1

Firmware parameters for distributing a bearing neck differential in the left cup (table 3)
Firmware number	Diameter of calibrating surfaces, mm
Firmware number	D	D1	D2	D3	D4	D5	D6
Second First	55-0.2 56-0.2	55.2 56.4	55.4 56.4	55.6 56.8	55.8 57.0	56.0 57.2	56.2 57.4

The worn journal for the driven bevel gear up to a diameter of less than 178.0 mm is restored by vibro-arc surfacing, without cooling.

The neck is surfacing up to Ø 181 mm with wire Sv-0.8 Ø1.6 mm at a wire feed speed of 1.3 m/min, a rotational speed of the part of 1.1 min1 and a surfacing step of 2.5 mm/rev.</p >

The deposited neck is turned to Ø 178.3 mm, providing a fillet with a radius of not more than 1.5 mm, and ground to a nominal Ø 178-0.027 mm and a surface roughness of 2.5 microns.

When restoring the cups of the differential box, the following requirements for the relative position of the surfaces must be met:

• - the axis of the surface of the holes for the spikes of the differential cross, must be in the plane of the junction of the cups - the permissible deviation is not more than 0.05 mm;
• - the axes of the surfaces of the holes for the spikes of the cross must be perpendicular to each other with a deviation of no more than 0.05 mm;
• - displacement of the center of the axes of the surfaces of the holes for the spikes of the differential cross with respect to the axis of the surfaces for the pins of the side gears should not exceed 1 ± 0.05 mm;
• - the non-concentricity of the mating surfaces of the cups and the neck for the differential bearing is allowed no more than 0.03 mm;
• - non-perpendicularity of the bearing surface under the side gear and the surface under the pin of the side gear is allowed no more than 0.05 mm;
• - non-perpendicularity of the surfaces of the differential bearing stop, cup connector and flange of the bevel driven gear (for the right cup) relative to the cup mating surface is allowed no more than .05 mm;
• - non-concentricity of the spherical surface under the pinion washers, the surface under the pin of the side gear and the surface of the neck under the driven bevel gear (for the right cup) relative to the resistance surfaces should not exceed 0.05 mm;
• - the center of the spherical surface must lie in the plane of the cups parting with a deviation of no more than 0.05 mm.

The rear wheel hub and the spacer ring of the hub bearings are made of 40L steel. The end surfaces M and H of the spacer ring (Fig. 8) are hardened to a hardness of at least HRC 40 to a depth of 2–5 mm.

The hub is restored when the holes for the outer rings of the inner and outer bearings are worn.

When the hole for the outer ring of the inner bearing is worn to a diameter of more than 159.99 mm, it is restored by setting the sleeve.

To do this, the hole for the bushing is bored to Ø 166 + 0.08 mm to a depth of 71 mm and a surface roughness of 2.5 microns, chamfered 1x45 °, the bushing is pressed in with an outer 166 mm, providing an interference fit in the range of 0.08-0 ,20 mm, bore a hole in the sleeve for the outer ring of the bearing up to 160 mm and a surface roughness of 2.5 microns and chamfer 2 x 30 ° at the end of the sleeve.

The holes are machined on a lathe in a faceplate, based on a surface Ø 300 + 0.084 mm, the runout of which relative to the surface of the hole for the bearing ring should not exceed 0.1 mm.

The hole for the outer ring of the outer bearing, worn to a diameter of more than 214.98 mm, is restored by setting the bushing or vibro-arc surfacing.

When restoring the hole by setting the sleeve, the hole is bored to Ø 221 + 0.09 mm at a length of 40 mm and a surface roughness of 2.5 microns.

Then, a repair sleeve with an outer Ø 221 mm is pressed into the bored hole until it stops against the shoulder, providing an interference in the range of 0.1–0.25 mm, a hole in the sleeve is bored to Ø 215 mm and a surface roughness of 2.5 microns and a chamfer 2x30° at the end of the hub, while facing the hub flush with the metal of the hub.

When boring, the hub is fixed on the faceplate, based on the seating surface of the brake drum.

When restoring the hole for the outer ring of the outer bearing by surfacing, the hole is bored to Ø 217 + 0.5 mm over a length of 40 mm, the surface of the hole is welded up to Ø 211 mm with OBC wire Ø 1.8 mm at a rotational speed of the part 1.2 min1, wire feed speed 1.2 m/min and deposition step 2.5 mm/rev without cooling. Surfacing is performed in several layers.

The welded hole is bored Ø 215’ mm, providing a fillet with a radius of 1.5 mm at the end of the boring and a surface roughness of 2.5 µm.

The axes of the surfaces of the holes for the outer rings of the bearings must lie on the same straight line with a deviation of no more than 0.05 mm.

The spacer sleeve is restored with wear, risks and wear of the end surfaces to a size of less than 118.0 mm (see Fig. 8).

If there is a specified defect, a repair sleeve is installed on the side of the mating surface of the end of the ring with the inner bearing (see Fig. 8).

To do this, the end of the ring is cut off, a size of 106 mm is provided to the second end, a hole for the repair sleeve is bored to 0 98 + 0.07 mm to a depth of 7 mm and a surface roughness of 2.5 microns, a chamfer of 0.5x45 ° is removed in the hole and a chamfer 2x45 ° on the outer surface for welding.

Then the bushing is pressed into the hole and welded with a circular seam with Sv-0.8 wire Ø 1.6 mm at a wire feed speed of 1.2 m/min and a part rotation frequency of 1.5 min.

Surfacing 4 is carried out under a layer of flux AN-348A. Then the end of the sleeve is cut to a size of 119-0.1 mm from the opposite end, a chamfer of 2.0 x 45 is bored and the surface of the end of the ring is hardened. h. to a depth of 2.5-5.0 mm to a hardness of at least HRG 40.

After hardening, the surface of the end face of the ring is ground on a surface grinder, providing a total length of the spacer ring (118.5 ± 0.2) mm and a surface roughness of 2.5.

It is allowed to surfacing the worn surface of the end of the ring up to a size of 120.5 mm with an electrode of the UONI-13/55 0 4 mm brand, followed by processing described for the option of setting the sleeve.

The second end of the spacer sleeve is restored in the same way, observing the entire sequence and dimensions, with the exception of boring the hole for the repair sleeve (see Fig. 8) to Ø 128 + 0.08 mm.

The surfaces of the ends M and H must be parallel to each other with a deviation of no more than 0.05 mm.

When assembling the gearbox, the seating and mating surfaces of the parts are lubricated with oil, the seals with paste or nitro-paint, and the working edges of the seals with Litol-24 grease.

The bearings are washed with kerosene or kerosene, followed by lubrication with working oil.

To assemble the central gearbox, you must first assemble the drive gear, for which:

• - press the stuffing box 8 (see Fig. 1) into the bearing housing cover to a depth of 6 mm from the front end of the cover using the mandrel shown in pis. 9, avoiding misalignment of the oil seal and its deformation;
• - press the outer races of bearings 4, 7 (see Fig. 1) into the bearing housing until it stops against the shoulder. In this case, it is recommended - to heat the bearing housing in oil to a temperature of 60-70 ° C;
• - press the inner tapered bearing 4 onto the shaft of the drive bevel gear until it stops;
• - put a spacer ring, shims 6 on the gear shaft, install the gear into the bearing housing;
• - install the second tapered bearing 7, flange 9, sealing ring 12, washer 11 on the gear shaft and tighten the flange nut 10 to a torque of 450-600 Nm (45-60 kgf / m);
• - adjust tapered bearings with preload.

After the final assembly of the drive gear, the differential should be assembled, for which:

• - press the bearing onto the right differential cup until it stops using a mandrel (Fig. 9);

• - install the bronze washer in the right differential cup, lubricating it with liquid oil;
• - insert a semi-axial gear lubricated with liquid oil into the bore of the right cup. A properly installed side gear should turn easily by hand;

lubricate the spikes of the differential cross with liquid oil;

• - put thrust washers of bushings of satellites, satellites with bushings on the spikes and put on bearing washers of satellites, lubricating the indicated parts;
• - install the cross with satellites and washers in the sockets of the right cup, pressing the cross to the seat of the cup, check the lateral clearance between the gear teeth and ease of turning.

When one (any) or two satellites are rotated by hand, the rest, as well as the side gear, should also rotate;

• - press the bearing onto the left differential cup until it stops using the mandrel shown in fig. 9, and gear 3 (see Fig. 1) on the pins of the cup until it stops;
• - install the support washer and side gear in the left cup (similar to installing them in the right cup);
• - move the crosspiece with satellites and washers to the left cup (similar to the right cup), check the side clearance;
• - holding the axle gear with your fingers, put the right cup on the left cup through the hole for the axle shaft in the right cup, putting it on the pins and aligning the numbers of the set of differential cups.

Install the cup mounting bolts and locking plates so that they cover the pins, tighten the nuts to a torque of 210-260 Nm (21-26 kgf m), bend the plates on the edges of the nuts;

• - insert the splined reference into one of the side gears and make a few turns - the differential gears should rotate easily, without knocking and jamming from the efforts of the hand.

Total assembly of the central gearbox should be done in the following order:

• - install the gearbox housing on the fixture so that the hole for the cup of the drive gear 5 (see Fig. 1) is at the bottom;
• - lubricate the differential bearings with liquid grease, put on the outer races and install the previously assembled differential into the housings of the crankcase bearings;
• - install the centering pins (bushings) in the sockets of the supports for the bearings, put the covers, locking plates and pre-tighten the bolts;
• - tighten nuts 20;
• -adjust differential bearings with preload;
• - turn the gearbox crankcase so that you can install the drive gear assembly with bearings in the crankcase;
• - adjust the meshing of the bevel gears;
• - tighten the bolts of the covers to a torque of 250-280 Nm (25-28 kgf), then locking them with plates, bending them on the verge of the bolts and the cover;
• - fully tighten all the nuts of the studs securing the drive gear bearing housing to the gearbox map;
• - put stoppers of 27 differential bearing nuts and press them with bolts with spring washers.

The central gearbox of the middle axle is disassembled during repair in the following sequence:

• - remove differential lock mechanism 20;
• - unscrew the bolts and remove the crankcase assembly with the axle drive shaft 30 and the center differential 29: when removing the crankcase, it is necessary to turn the flange to ensure the differential exits from behind the gear;
• - remove the flange 17, unscrew the cover fastening bolts 15, remove the glass together with the bearing 14 from the shaft 30 and the differential lock clutch 19 using a universal puller;
• - unscrew the bolts securing the cups of the necks of the center differential 29 and remove the cup with the gear and the bearing from the shaft 30
• - remove the retaining ring, pin and unscrew the nut fastening the cross 28;
• - remove cross 28 from shaft 3, remove gear 25 with bearings using a puller 13;

• - remove the inner ring of the outer bearing of the cylindrical gear using a puller with a mandrel 3 (Fig. 10) during partial disassembly, when it is necessary to remove only the shaft 30 (see Fig. 11) of the axle drive assembly with the center differential 29, unscrew the bolts securing cover 15 and remove the axle drive shaft together with the center differential.

In this case, to remove it, it is necessary to set the flat on the differential cups by turning the shaft 30 so that the cups do not touch the gear 10.

To remove, if necessary, the inner race of the cylindrical bearing of the center differential, use a universal puller;

• - unscrew the nuts and remove the drive gear 3 with the crankcase 8 bearings and the spur gear 10 as an assembly;
• - clamp the drive bevel gear 3 in a vise (the jaws of which are covered with soft metal pads), unscrew the nut 11 and remove the gear 10;
• - remove the inner ring of the inner tapered bearing from the drive gear shaft 3 using a puller with a mandrel 6 (see Fig. 2);

• - if necessary, press out the outer rings of bearings 9 from the crankcase 8 (see Fig. 11) using a puller (see Fig. 3);
• - remove stoppers 50 (see fig. 11) and covers 48 of differential bearings 47;
• - remove differential 43 assembly;
• - unscrew the nuts of the bolts of the differential cups and disassemble the differential 43 using the dismantling bolts, remove the satellites 1, side gears 45, washers 46;
• - if necessary, remove the differential bearings 47 using a puller;
• - unscrew the bolts 36 (see Fig. 11) and remove the shaft 32 complete with bearings 35, unscrew the nut 40 and disassemble the shaft;
• - if necessary, disassemble the differential lock mechanism 20.

The disassembled parts of the gearbox must be washed and the condition of the working surfaces of bearings and gears checked.

Gear teeth should not have chips, cracks, chipping of the cementation layer, as well as severe wear.

With a slight step development of the teeth, the steps are cleaned; it is also necessary to clean the nicks and burrs on the gear teeth.

The wear of the teeth of bevel gears in terms of thickness is characterized by the amount of backlash. The gap is measured with an indicator from the side of the larger diameter.

If the gears of the central gearbox are noisy, the side clearance of 0.8 mm can serve as a basis for replacing the bevel gear pair.

If necessary, the driving and driven bevel gears are replaced as a set, since at the factory they are selected in pairs according to the contact patch and backlash.

When replacing bevel gears, a pair of middle axle gears must be installed. Installation of rear axle gears is not allowed.

When inspecting the parts of the differential, pay attention to the condition of the surface of the necks of the cross, the holes and spherical surfaces of the satellites, the bearing surfaces of the side gears, the bronze bearing washers and the end surfaces of the differential cups.

These surfaces must be free of burrs and wear.

When defecting parts of the rear and middle axles of the car, you should be guided by the nominal and permissible dimensions given in the table.

Nominal and allowable sizes
Controlled diameter	Size, mm
	Rated	Valid without repair
Axle gearbox housing holes for differential bearings Bearing holes for drive bevel gear shaft: front rear Journals for the front bearing of the pinion shaft Journals for the rear bearing of the pinion shaft Differential cross stud Holes in differential pinion hub Holes for the tires of the cross in the differential cup (right, left) Holes for the neck of the axle shaft gear in the differential cup (right, left) Axle pinion journals Holes for the pinion axle of the wheel gear cup (inner, outer skinny) Outer pinion axle Curses for wheel gear hub bearing Neck for inner wheel bearing Holes for the outer ring of the outer bearing of the wheel hub Holes for the outer ring of the inner wheel bearing	160+0.010-0.030 140-0.012-0.052 170-0.012-0.052 65-0.012-0.032 80+0.04+0.02 32-0.025-0.064 32+0.05 32-0.027 70+0.12 69.8 30+0.045 30-0.014 120+0.026 100+0.075 215-0.015 180-0.015	160.04 140.0 170.0 64.95 80.0 31.85 32.10 32.3 70.3 69.5 30.07 29.98 119.95 99.9 214.9 179.9

In case of significant wear or loosening of the satellite bushing, it must be replaced.

The processing of a new bushing must be done after pressing it into the satellite to a diameter of 32^+0.05mm.

In case of significant wear of the bronze support washers of the side gears and satellites, the washers must be replaced. The thickness of the new bronze washers is 1.5 mm.

Before assembly, the seating and mating surfaces of the gearbox parts must be lubricated with working oil, it is recommended to lubricate the gaskets with grease, sealing paste or nitro paint, and the working edges of the seals with Litol-24 grease.

The bearings must be washed in kerosene, then lubricated with working oil.

The assembled rear axle after repair must be tested on the stand.

Before testing, industrial oil 12 or 20, heated to a temperature of 60 ° C, is poured into the wheel gear and rear axle housings.

To fill the wheel drive with oil, remove the small cap and fill with oil up to the lower edge of the hole in the large cap.

In addition, grease can be poured into the wheel drive through the drain plug hole by turning the hub so that the edge of the hole for the small cover is on the same horizontal line with the hole for the drain plug.

In this case, the oil is poured up to the level of the drain plug hole.

In the rear axle housing, oil is poured through the hole in the rear cover to the edge of the hole.

A connecting head is screwed into the opening of the rear axle housing under the breather, a hose is connected and the rear axle is filled with air, bringing the pressure to 0.02-0.04 MPa (0.2-0.4 kg / cm ² ).

In the event that oil leaks through welded joints, they are welded, and in case of oil leaks through flanged joints, they are tightened with bolts.

Then, the rear axle is tested at a drive gear shaft speed of 900-1500 min1 according to the mode given in the table.

Rear axle test mode
Test conditions	Braking Torque on each axle shaft, kgf/m	Duration tests, min
No load	-	5
Under load	50	10

To check the operation of the differential and wheel drive, it is necessary to completely brake the drums in turn for 0.5-1.0 minutes, supplying compressed air to the corresponding brake chamber.

When testing the rear axle, the following are not allowed: increased, uneven noise of gears, knocking of gears, sticking of the differential, heating of the brake drums, oil leakage through the seals and connections.

A slight appearance of oil stains at the joints and gland seals is allowed.

At the end of the test, the degree of heating of the gearbox gear bearings, differential and wheel hubs is checked by touch.

A slight increase in the temperature of the corresponding places of the crankcases and hubs is allowed.

In case of excessive heating, it is necessary to check the tightness and adjustment of the bearings.

The defects identified during the testing of the rear axle are eliminated and the rear axle is re-checked on the stand.