Contents: Differential assembly ↓ Installing and adjusting the drive…↓ Adjusting the pinion bearings ↓ Installing the differential box ↓
Rear axle gearbox parts
1 – drive gear flange; 2 – oil seal; 3 – oil deflector; 4 – front bearing; 5 – rear bearing; 6 – drive gear adjusting ring; 7 – axle shaft gear support washer; 8 – axle shaft gear; 9 – satellite; 10 – satellite axis; 11 – driven gear; 12 – differential box; 13 – differential box bearing; 14 – adjusting nut; 15 – lock plate mounting bolt; 16 – locking plate; 17 – locking plate; 18 – bolt for fastening the driven gear to the differential box; 19 – drive gear; 20 – cover mounting bolt; 21 – spring washer; 22 – gasket; 23 – bolt for fastening the gearbox to the rear axle beam; 24 – gearbox housing; 25 – spacer sleeve; 26 – flat washer; 27 – drive gear flange fastening nut
Reliable operation of the gearbox is ensured by strict adherence to the following assembly and adjustment techniques.
Differential assembly
1. Lubricate with transmission oil and install the axle gears with support washers and satellites through the windows in the differential box.
2. Turn the satellites and axle gears so that the axis of rotation of the satellites is aligned with the axis of the hole in the box, then insert the satellite axis.
3. Check the axial clearance of each axle gear: it should be 0–0.10 mm, and the torque of the differential gears should not exceed 14.7 N·m (1.5 kgf·m).
4. If the clearance is increased, which is a sign of wear of the differential components, replace the axle gear support washers with others of greater thickness. If the specified clearance cannot be achieved even when installing washers of the greatest thickness, replace the gears with new ones due to their excessive wear.
5. Install the driven gear on the differential case.
6. Using mandrel A.70152, press the inner rings of the roller bearings onto the differential box.
Installing and adjusting the drive gear
Main gears
1 – driven gear; 2 – serial number; 3 – correction in hundredths of a millimeter to the nominal position; 4 – leading gear
The correct position of the drive gear relative to the driven gear is ensured by selecting the thickness of the adjusting ring installed between the thrust end of the drive gear and the inner ring of the rear bearing.
Select the adjusting ring using the A.70184 mandrel and the A.95690 device with an indicator.
1. Having secured the gearbox housing on the stand, press the outer rings of the front and rear bearings of the drive gear into the housing sockets, using mandrels for this: for the front bearing - A.70185, and for the rear - A.70171 (1).
2. On the A.70184 mandrel (4), simulating the drive gear, install the inner ring of the rear bearing (3) using the A.70152 mandrel and insert the mandrel into the neck of the gearbox housing (2 - device A.95690).
3. Install the front bearing inner race, pinion flange and, while rotating the mandrel to correctly install the bearing rollers, tighten the nut to a torque of 7.8–9.8 N·m (0.8–1 kgf·m).
4. Fix the device A.95690 on the end of the mandrel 4 and set the indicator 1, which has divisions of 0.01 mm, to the zero position by installing its leg on the same end of the mandrel A.70184. Then move the indicator so that its leg stands on the seating surface of the differential box bearing (see fig. in p.2).
5. By turning the mandrel 1 with the indicator to the left and to the right, set it in such a position in which the indicator arrow marks the minimum value "a1" and write it down. Repeat this operation on the seating surface of the second bearing and determine the value "a2" (2 - device A.95690).
6. Determine the thickness "S" of the drive gear adjusting ring, which is the algebraic difference between the values "a" and "b":
S = a – b, where:
– a – the arithmetic mean distance from the ends of mandrel 1 to the journals of the differential bearings;
– a = (a1 a2)/ 2;
– b – deviation of the drive gear from the nominal position, translated into mm. (see fig. in p.5).
7. The deviation value is marked on the drive gear (see fig. Main transmission gears) in hundredths of a millimeter with a plus or minus sign.
8. When determining the thickness of the adjustment ring, take into account the sign of the quantity "b" and its unit of measurement.
Example
Let's assume that the value "a" set with the indicator is 2.91 mm (the value "a" is always positive), and the deviation "-14" is set on the drive gear after the serial number. To get the value "b" in millimeters, you need to multiply the specified value by 0.01 mm.
b= -14·0.01 mm= -0.14 mm
Determine the thickness of the adjusting ring for the drive gear in millimeters.
S = a – b = 2.91 mm – (-0.14 mm) = 2.91 mm + 0.14 mm =3.05 mm
In this case, install an adjustment ring with a thickness of 3.05 mm.
9. Place the adjusting ring (3) of the required thickness on the drive gear (4) and press on the inner ring of the rear (1) bearing, removed from the A.70184 mandrel, using the A.70152 mandrel (2). Place the spacer sleeve on.
10. Insert the pinion gear into the gearbox housing and install the front bearing inner race, oil deflector, oil seal, pinion gear flange and washer onto it.
11. Screw a nut onto the end of the gear and, having locked the flange of the drive gear, tighten it (for tightening torque, see below).
Adjusting the pinion bearings
Dynamometer 02.7812.9501
1 – movable pointer; 2 – Torque limit indicator; 3 – body; 4 – handle; 5 – a rod with a tip inserted into the adapter sleeve of the drive gear flange fastening nut
1. To limit axial displacements of the drive gear under operating loads, it is very important to create a preload in its bearings within specified limits. The preload is controlled by a dynamometer 02.7812.9501 (see fig. Dynamometer 02.7812.9501), measuring the moment of resistance to rotation of the drive gear.
2. The torque resistance determines the degree of bearing tightening. It should be 157–198 N cm (16–20 kgf cm) for new bearings and 39.2–58.6 N cm (4–6 kgf cm) for bearings with a mileage of 30 km or more.
3. The flange nut should be tightened to a torque of 117–255 N·m (12–26 kgf·m), periodically checking the moment of resistance of the bearings to turning the drive gear with a dynamometer.
4. To check the moment of resistance, place the dynamometer 1 on the adapter sleeve 3 (2 – crankcase).
5 Set pointer 2 (see fig. Dynamometer 02.7812.9501) torque limitation on the scale division corresponding to 196 N cm (20 kgf cm), and use handle 4 to make several turns clockwise.
6. When turning the drive gear, movable indicator 1 should not go beyond indicator 2 and should show at least 157 N cm (16 kgf cm).
7. If the torque of resistance to rotation is less than 157 N cm (16 kgf cm), and for bearings after a run of 30 km or more - 39.2 N cm (4 kgf cm), then tighten the flange nut of the drive gear (without exceeding the specified tightening torque) and check again the moment of resistance to turning of the drive gear.
8. If the torque resistance is more than 198 N cm (20 kgf cm), and for worn bearings 58.8 N cm (6 kgf cm), which indicates that the bearing preload is too high, replace the spacer sleeve, since it has been deformed due to excessive load to a size that does not allow correct adjustment.
9. After replacing the spacer sleeve, repeat assembly with appropriate adjustments and checks.
Installing the differential box
Checking the differential box bearing preload with the A.95688/R device
1 – mounting screw; 2 – key A.55085; 3 – driven gear; 4 – adjusting nut; 5 – intermediate lever; 6 – fastening screw; 7 – indicator bracket; 8 – bracket tightening screw; 9 – indicator for checking the preliminary tension of the differential box bearings
Checking the lateral clearance in the engagement of the main transmission gears using the device A.95688/R
1 – bracket tightening screw; 2 – indicator for checking the lateral clearance in the engagement of the driving and driven gears; 3 – screw for fastening the indicator rod; 4 – indicator bracket; 5 – fastening screw; 6 – driven gear
1. Install the pre-assembled differential box into the crankcase together with the outer bearing rings.
2. Install two adjusting nuts 4 (see fig. Checking the differential box bearing preload with device A.95688/R) so that they come into contact with the bearing rings.
3. Install the bearing caps and tighten the mounting bolts with a torque wrench.
4. Preloading the differential box bearings and adjusting the lateral clearance in the engagement of the main gear gears. These operations are performed simultaneously using the A.95688/R device and the A.55085 key.
5. Attach the device to the gearbox housing (see fig. Checking the differential box bearing preload with device A.95688/R) screws 1 and 6, screwing them into the holes for the bolts for fastening the locking plates of the adjusting nuts.
6. Move bracket 7 along the guide of the device until the lever touches the outer side surface of the cover and tighten screw 8. Loosen screws 1 and 3 (see fig. Checking the lateral clearance in the engagement of the main transmission gears using the device A.95688/R), and install bracket 4 so that the indicator leg rests on the side surface of the driven gear tooth at the edge of the tooth, then tighten screws 1 and 3.
7. By turning the adjusting nuts, pre-adjust the lateral clearance between the teeth of the driving and driven gears within 0.08–0.13 mm. The clearance is checked using indicator 2 while rocking gear 6. In this case, the bearings should not have a preliminary tension.
8. The adjusting nuts must only be in contact with the bearings, otherwise the correct preload measurement will be impaired.
9. Sequentially and evenly tighten the two bearing adjusting nuts (1, 2), while the differential bearing caps diverge, therefore, the distance "D" increases. This divergence is marked by indicator 9 (see fig. Checking the differential box bearing preload with device A.95688/R), on the leg of which lever 5 acts.
10. The nuts for adjusting the differential box bearings are tightened until the distance "D" increases (see fig. in p.9) by 0.14–0.18 mm.
11. Having set the exact preload of the differential box bearings, finally check the lateral clearance in the engagement of the main gear gears, which should not change.
12. If the clearance in the gear engagement is greater than 0.08–0.13 mm, then move the driven gear closer to the driving gear or move it away if the clearance is smaller. To maintain the set bearing preload, move the driven gear by tightening one of the bearing adjusting nuts and loosening the other by the same angle.
13. To perform this operation accurately, watch the indicator 9 (see fig. Checking the differential box bearing preload with device A.95688/R), which shows the value of the previously set bearing preload.
14. After tightening one of the nuts, the indicator reading will change as the "D" divergence increases (see fig. in p.9) caps and preload of bearings. Therefore, loosen the other nut until the indicator arrow returns to its original position.
15. After moving the driven gear along indicator 2 (see fig. Checking the lateral clearance in the engagement of the main transmission gears using the device A.95688/R) check the side clearance. If the clearance is not within the norm, repeat the adjustment.
16. Remove the A.95688/R tool, install the adjusting nut locking plates and secure them with bolts and spring washers. Spare parts come in two types of locking plates: with one or two tabs, depending on the position of the nut slot.
17. Adjustment and repair of gearbox units is performed on a stand, where the gearbox can also be tested for noise and the location and shape of the contact patch on the working surfaces of the teeth can be checked, as indicated in the subsection 5.4.7.7.