6.4.4. Adjustment of the back bridge

Bearings of the back bridge, side gap and the provision of a spot of contact in gearing of the main couple regulate at the plant, and, as a rule, they do not demand adjustment at operation. Their adjustment is necessary only after a partition of the bridge and replacement of details, and also at big wear of bearings. The side gap in gearing of the main transfer which increased owing to wear of teeths, adjustment do not reduce as it leads to violation of gearing and, as a result, to the increased noise of the back bridge or breakage of teeths. The side play in conic bearings is eliminated, without violating the mutual provision of the conducted and conducting gear wheels.
Adjustment of a pretightness of bearings of the leading gear wheel
Need for adjustment of bearings can be determined by existence of an axial side play of the leading gear wheel. An axial side play measure at the disconnected driveshaft by means of the indicator with the division price no more than 0,01 mm when moving a flange in the axial direction. The indicator leg at the same time has to rest against a flange end face parallel to an axis of the leading gear wheel.

Fig. 5.32. Zadny Bridge with a beam like a banjo with a separate reducer (middle part): 1 — a nut; 2 — a flange of the leading gear wheel; 3 — a cuff; 4, 6, 11 — bearings; 5 — a ring; 7 — an adjusting ring; 8 — a reducer case; 9 — the leading gear wheel; 10 — differential; 12 — a half shaft; 13 — laying; 14 — a lock plate; 15 — a case; 16 — a nut of bearings of differential; 17 — a differential bearing cover; 18 — a stopper of a maslozalivny opening; 19 — the conducted gear wheel; 20 — сапун




The axial gap in bearings of the leading gear wheel should be eliminated with adjustment of a preliminary tightness. The preliminary tightness is regulated by selection of thickness of an adjusting ring 5 (see fig. 5.32).
Adjustment needs to be executed as follows:
— to rasshplintovat and turn off a nut 1, to remove a flange 2, an epiploon 3 and an internal ring of the bearing 4;
- to replace an adjusting ring 5 new which thickness has to be less than the axial side play replaced with size plus in addition of 0,05 mm at a run of the car it is less than 1000 km or 0,01 mm — at a car run more than 10 000 km;
- to put into place an internal ring of the bearing, a new epiploon, a flange and to tighten a nut the moment of 160 — 200 N · m (16 — 20 kgfs · l), then to check ease of rotation of the leading gear wheel. If rotation of the leading gear wheel requires bigger effort, than was before adjustment, then it is necessary to replace an adjusting ring, having increased its thickness by 0,01 — 0,02 mm.
After the end of adjustment of a pretightness of the bearing it is necessary to tighten a nut the moment of 160 — 200 N · m (16 — 20 kgfs · l) before coincidence of a cut in a nut with an opening under the forelock. The nut for coincidence of an opening under the forelock with a cut of a nut needs to be tightened only, otherwise because of an insufficient inhaling perhaps provorachivany an internal ring of the external bearing, wear of an adjusting ring and, as a result, increase in an axial side play of bearings. At an inhaling of a nut of a flange it is necessary to make a provorachivaniye of the leading gear wheel for the correct installation of rollers in bearings.
After adjustment it is necessary to check heating of bearings after the movement of the car with a speed of 60 — 70 km/h within 20 — 30 min. At the same time heating of a mouth of a case should not exceed 95 °C (the water which got on a mouth should not boil). At excessive heating it is necessary to reduce a pretightness.
To make adjustment of a pretightness when replacing bearings of the leading gear wheel and gear wheel of the main transfer in the following order:
- it is necessary to adjust the provision of the leading gear wheel by selection of an adjusting ring 7 (see fig. 5.32), having provided the size of (109,5±0,02) mm — distance between the general axis of semi-axial gear wheels and the end face of the leading gear wheel adjacent to an adjusting ring 7;
- selection of an adjusting ring 5 to adjust a pretightness of bearings of the leading gear wheel. At the correct adjustment the moment of resistance to rotation of the leading gear wheel has to be in limits of 150 — 200 N · m (15 — 10 kgfs · cm) for new bearings or 70 — 100 N · m (7 — 10 kgfs · cm) for the working bearings. If the moment of resistance to rotation of bearings appears within norm, it is necessary to zashplintovat a nut, otherwise it is necessary to repeat adjustment. At the same time, if the moment of resistance to rotation appeared less demanded, it is necessary to reduce thickness of an adjusting ring and if more — it is necessary to pick up a ring of bigger thickness.
After adjustment of a pretightness of bearings it is necessary to establish to the bridge differential assembled and to make adjustment of a pretightness of bearings of differential and a side gap in gearing of gear wheels of the main transfer.
Adjustment of a pretightness of bearings of differential and side gap in gearing of gear wheels and the main transfer
Adjustment without replacement of bearings.
It is necessary for adjustment of bearings:
- to remove half shafts, a cover of a case and laying of a cover (for the one-piece back bridge);
- to remove half shafts and to take out a reducer from a bridge case (for the back bridge with a beam like a banjo);

Fig. 5.33. Check of an axial gap in differential bearings (the bridge with a beam like a banjo)




- at the removed lock plates 14 (see fig. 5.32) and the weakened covers of 17 bearings of differential 16 to install by adjusting nuts an axial gap of 0,01 mm in differential bearings (see fig. 5.33)

Fig. 5.34. Check of a side gap in gearing of teeths of gear wheels of the main transfer (the bridge with a beam like a banjo)




- to install the indicator, as shown in fig. 5.34 and to check a side gap in gearing of gear wheels which has to be within 0,15 — 0,25 mm. To make check in not less than in six points, every time turning a gear wheel;
- to release for increase in a side gap an adjusting nut from the conducted gear wheel and on as much grooves to wrap an opposite nut. For reduction of a side gap the specified operations are carried out upside-down;
- to adjust the size of a prednagyag for what to squeeze bearings in the axial direction:
• on 0,1 mm at a car run less than 1000 km;
• on 0,05 mm at a run more than 10 000 km;
• to exercise control on an angle of rotation of an adjusting nut. The turn of one nut towards to another on width of a groove corresponds to compression of bearings on 0,05 mm;
- to tighten bolts of fastening of covers of bearings of differential and to check a side gap of gearings of teeths of gear wheels of the main transfer;
- to fix by bolts lock plates on covers of bearings;
- to establish a reducer in a bridge case;
- to establish half shafts.
Adjustment when replacing bearings.
It is necessary for adjustment of bearings:
- to remove half shafts, a cover of a case and laying of a cover (for the one-piece back bridge);
- to remove half shafts and to take out a reducer from a case (for the back bridge with a beam like a banjo);
- to remove lock plates 14 (see fig. 5.32) from covers of 17 bearings of differential;
- to turn off bolts of fastening of covers, to uncover, take out differential and adjusting nuts 16;
- to measure by a dynamometer the residual moment of friction of bearings of the leading gear wheel;
- to vypressovat internal rings of bearings from a differential box and to napressovat new;
- to deliver into place differential with new bearings, having densely drawn in their external rings;
- to insert adjusting nuts 16 into a carving part of a case of the back bridge, is whenever possible closer to bearings and to establish covers 17 according to the available markings on covers of bearings and on a case of the back bridge;
- to fix covers of bearings by bolts with the effort which is not interfering screwing up of adjusting nuts 16 (openings in a case under bolts have to be greased previously with anaerobic sealant);
- to draw in bearings adjusting nuts before receiving a small pretightness. During preload of bearings the conducted gear wheel needs to be turned on several turns in one, then in other party for the correct installation of rollers in bearings;
- serially tightening adjusting nuts of bearings of differential, to achieve increase in the moment of resistance to rotation of the leading gear wheel by 150 — 300 N · m (15 — 30 kgfs · cm) rather residual moment of resistance to rotation measured later removals of differential;
- to install the indicator, as shown in fig. 5.34 and to check a side gap in gearing of gear wheels which has to be within 0,15 — 0,25 mm. For increase in a gap to release a regilirovochny nut from the conducted gear wheel and on as much grooves to wrap a nut from the leading gear wheel for preservation of a pretightness of bearings. For reduction of a side gap the specified operations are carried out upside-down;
- rotation of adjusting nuts needs to be finished with an inhaling. For example, if it is required to release a nut on one groove, then it is necessary to release it on two, and then on one groove to tighten. It guarantees contact of a nut with an external ring of the bearing and lack of shift of a ring during the work;
- to finally tighten bolts of fastening of covers of bearings, to fix by bolts lock plates on covers of bearings;
- to establish laying and a back cover (for the one-piece back bridge);
- to establish a reducer in a bridge case (for the back bridge with a beam like a banjo);
- to establish half shafts.
Check of gearing on a contact spot
After final assembly and adjustment of a reducer of the bridge it is necessary to check gearing of gear wheels. For this purpose it is necessary to paint teeths paint. It is necessary to consider that very liquid paint spreads and soils a surface of teeths, too dense — it is not squeezed out of intervals between teeths. Braking the conducted gear wheel, rotate in both directions the leader until the accurate spot of contact is designated.

Fig. 5.35. Spot of contact of gear wheels of the main transfer: I \party of the forward course (worker); II \party of a backing; 1 — the correct contact in gearing of gear wheels of the main transfer at small loading; 2 — contact at tooth top (for correction the leading gear wheel is moved by conducted); 3 — contact on a fang (for correction the leading gear wheel is removed from conducted); 4 — contact on the narrow end of tooth (for correction remove the conducted gear wheel from the leader; 5 — contact on the wide end of tooth (for correction the conducted gear wheel is moved to the leader)




Check of installation of gear wheels and side gap in gearing comes to the end with receiving the correct spot of contact of teeths. The side gap has to be within stated limits. In fig. 5.35 typical spots of contact on teeths of the conducted gear wheel of the main transfer of the back bridge are shown.

Fig. 5.36. The correct arrangement of a spot of contact on the conducted gear wheel




The contact spot on both sides of tooth of the conducted gear wheel has to settle down, as shown in fig. 5.36.
If in the course of adjustment there is a need for movement of the leading gear wheel, then it can be reached by change of thickness of set of the adjusting laying established between an end face of a gear wheel and an end face of an internal ring of the back bearing of the leading gear wheel.
At change of a side gap the contact spot arrangement changes. The contact in this case moves as follows:
1. For reduction of a side gap the conducted gear wheel moves to the leader, the contact spot on working (convex) side of tooth slightly moves below and closer by the narrow end of tooth;
2. For increase in a side gap the conducted gear wheel is taken away from the leader:
- on working side of tooth the contact spot slightly moves above and closer by the wide end of tooth;
- on non-working side of tooth the contact spot slightly moves above and closer by the wide end of tooth;
3. At approach of the leading gear wheel by conducted:
- the contact spot on the working party moves below and closer by the narrow end of tooth;
- the contact spot on the non-working party moves below and closer by the wide end of tooth;
4. At moving away of the leading gear wheel from conducted:
- the contact spot on working side of tooth moves to top of tooth and by its wide end;
- on non-working side of tooth the spot of contact moves to top of tooth and slightly moves by its narrow end.