3.4. Zadny Bridge

Possible malfunctions of the back bridge, their reason and ways of elimination

Features of a design

Fig. 3.65. Zadny Bridge: 1 – a half shaft with a brake; 2 – the plug is persistent; 3 – half shaft plate; 4 – bolt of fastening of a board of a brake; 5 – bearing; 6 – cuff; 7 – the plug is locking; 8 – case of the back bridge; 9 – reducer case; 10 – differential case; 11 – bolt; 12 – the gear wheel conducted; 13 – bearing of the leading gear wheel forward; 14 – the washer is maslootrazhatelny; 15 – cuff of the leading gear wheel; 16 – washer; 17 – flange of fastening of the driveshaft; 18 – nut; 19 – the plug is expansion; 20 – laying is adjusting; 21 – bearing of the leading gear wheel back; 22 – the gear wheel is leading; 23 – the washer is persistent; 24 – differential bearing; 25 – the nut is adjusting; 26 – stopper; 27 – laying; 28 – bolt; 29 – washer; 30 – bolt; 31 – half shaft gear wheel; 32 – stopper; 33 – finger of satellites; 34 – satellite; 35 – bearing cover; 36 – reducer cover; 37 – the stopper is magnetic; With – the assembly size


Zadny Bridge is leading. In a case of the back bridge (beam) of 8 (fig. 3.65) the reducer including the main transfer with differential and half shafts is established.

Fig. 3.80. Definition of an assembly gap And in a case of the main transfer: 1 – control mandrel; 2 – micrometric rack; 3 – mandrel


The case of the back bridge consists of two casings of the half shafts pressed by the free ends in a case of the 9th reducer and fastened with welding. Casings of half shafts represent pipes with the welded flanges, basic cups of springs and arms for fastening of elements of a suspension bracket and the brake system. The reducer of the back bridge includes gipoidny main transfer and interwheel differential. In a case of the 9th reducer on two roller conic bearings 13 and 21 the leading gear wheel 22 main transfers made for a single whole with shaft is placed. Between an end face of an external ring of the back bearing and a basic surface of a case of a reducer the adjusting laying 20 determining the provision of the leading gear wheel by the assembly size A = and + in is established (see fig. 3.80). Between roller conic bearings there is an expansion plug 19 (see fig. 3.65) which preliminary tightness is created by a nut of the 18th fastening of a flange of the 17th leader of a gear wheel. The speaker from a reducer case the end of a shaft of the leading gear wheel is condensed with a cuff 15. On a flange 17 the mud-reflector protecting a cuff from dirt and damages is established.
The conducted gear wheel of the 12th main transfer is attached by bolts 11 to a flange of the case of the 10th differential which rotates on two roller conic bearings 24 adjusted by the nuts 25 screwed in demountable beds of bearings. Each bearing is closed by the cover 35 attached by two bolts to a reducer case. Adjusting nuts 25 are fixed by a stopper 26. Two satellites 34 are installed on a finger 33. The finger of satellites refrains from drop-out by the conducted gear wheel 12 which blocks an opening. Conic teeths of satellites 34 are in continuous gearing with teeths of semi-axial gear wheels 31 which lean end faces on the case of the 10th differential.
Half shafts the internal shlitsevy ends enter gearing with vents of semi-axial gear wheels 31, and the external ends lean on the closed ball bearings 5 with sealants. The bearing is fixed on a half shaft via the persistent plug 2 by the locking plug 7. Last in a cold condition of a napressovan on a half shaft by effort of 98 100+1962 N (10 000+2000 kgfs). To a flange of a half shaft the brake drum and four bolts – a wheel disk fastens two screws.
In the lower part of a case of the 9th reducer (beam) the magnetic stopper of the 37th drain opening is established. Half shaft bearings – the closed type with the disposable lubricant put there on all service life before capital repairs of the car.
In use mobile details and knots of the back bridge are exposed to wear that begins to affect eventually work of all transmission and the bridge.
The nominal sizes, admissions, gaps and tightnesses of the main interfaced details, the most often subject to wear, are specified in tab. 3.5.

Table 3.5  the Nominal sizes, admissions, gaps and tightnesses in the main interfaced details of the main transfer and the back bridge

Definition of technical condition of the back bridge on noise
To facilitate searches of possible malfunctions, adhere to the following testing procedure.
Test No. 1.
Conduct the car on the highway with a speed about 20 km/h distinctly to define the nature of noise. Then gradually increase speed to 90 km/h, listening to change of noise and noting the speed at which it occurs.
Release a pedal of an accelerator and without snubbing reduce speed the engine. During delay you monitor change of noise and fix the moment of its strengthening or reduction. Usually noise arises and disappears at the same speeds both at acceleration, and at delay.
Test No. 2.
Accelerate the car to 100 km/h, put the gear shifting lever in neutral position, switch off ignition and, moving a setup, you watch the nature of noise at various speeds. If the noise noticed during this test same as at the first test, then it proceeds not from a reducer as this knot without loading does not publish noise. On the contrary, the noise noted at the first test and which is not repeating at the second can proceed from a reducer of half shafts or bearings. Define a source of this noise during the following test.
Test No. 3.
On the motionless and slowed-down car launch the engine and, increasing smoothly rotation frequency, compare the arisen noise with noticed in the previous tests: if they are similar to noise of the first test, so their source is not the reducer, but other knot, for example the air cleaner, the muffler, the engine or a body.
Test No. 4.
The noise found at the first test and which did not repeat at the subsequent proceed from a reducer. For confirmation lift back wheels, launch the engine, include the fourth transfer and be convinced that noise really arises in a reducer.

Removal
1. Weaken bolts of fastening of wheels to flanges of half shafts.
2. Raise a back part of the car and establish it on supports. Finally turn off bolts of fastening and remove wheels.
3. Turn off traffic jams oil-filling 32 (see fig. 3.65) and masloslivny 37 openings and merge oil from a case of the back bridge.
4. Turn off four bolts of fastening of the driveshaft to a flange 17 and disconnect the driveshaft.
5. Disconnect a back cable of the drive of the parking brake from an adjusting tip.
6. Disconnect flexible hoses of a hydraulic actuator of brakes from a collector and muffle their openings.
7. Disconnect pressure regulator rack from an arm on a beam of the back bridge.

Fig. 4.13. Back suspension bracket: 1 – plug expansion shock-absorber; 2 – nut; 3 – the shock-absorber is back; 4 – nut of fastening of the top bar; 5 – arm of the top bar; 6 – the bar is top; 7 – shock-absorber cover; 8 – the cover is restrictive; 9 – shock-absorber pillow; 10 – laying top springs; 11 – spring cup; 12 – spring; 13 – compression buffer; 14 – laying lower springs; 15 – the bar is cross; 16 – the bridge is back; 17 – nut; 18 – the plug is expansion; 19 – plug; 20 – the bar is lower; 21 – bolt of fastening of a bar; 22 – bolt of fastening of the shock-absorber; 23 – shock-absorber plug


8. Establish a jack under a bridge beam and disconnect the lower ends of shock-absorbers from bridge beam arms, having turned off nuts 2 (see fig. 4.13) and having taken out bolts 22.
9. Disconnect cross 15 and two longitudinal 6 and 20 bars on both sides from bridge beam arms, having turned off nuts with spring washers and having taken out bolts.
10. Lower a jack and remove the back bridge assembled. Be careful as at the same time springs of the 12th suspension bracket are released.
11. Establish the back bridge upside-down. Fill in oil in a bridge case and adjust the drive of the parking brake.

Dismantling of the back bridge
1. Turn out two directing hairpins of fastening of a drum to a nave and remove brake drums. If the drum is not removed, establish hairpins in carving openings of a flange of a drum and, screwing them, remove a drum.
2. Disconnect brake hydraulic actuator tubes from wheel cylinders, having turned off cap nuts.
3. Turn off a face key four bolts 4 (see fig. 3.65) fastenings of a brake board through a big opening in a half shaft flange.

Fig. 3.66. Removal of a half shaft by means of a stripper: 1 – bracket; 2 – flange; 3 – screw


4. Take out a half shaft 1 together with a brake board. If the half shaft is not taken out by a hand, take out it by means of a stripper, as shown in fig. 3.66.

       NOTE
Half shafts of the back bridge can be removed, without removing the back bridge. Dismantling order the same.

Fig. 3.67. A mandrel for a half shaft cuff press fitting in a nest of a flange of a case of the back bridge


5. For replacement of a cuff 6 (see fig. 3.65), take out it from a case of the back bridge and press a new cuff, previously having dipped it into engine oil, by means of a mandrel (fig. 3.67) against the stop into a case flange.
6. Collect the back bridge upside-down.
Definition of technical condition of half shafts
1. Replace the worn-out and damaged ball bearings 5 (see fig. 3.65), locking 7 and persistent 2 plugs. The radial gap in the bearing should not exceed 0,1 mm.
2. If the bearing or locking and persistent plugs are displaced concerning the seats, replace them.
3. Replace the damaged plates of 3 half shafts of fastening of bearings.
4. Replace a half shaft 1 if it is deformed and landing surfaces and vents are damaged or worn-out.
Dismantling of a half shaft
1. Remove the locking plug. The easiest to make it if to pierce it on outer diameter (or to sfrezerovat or were washed down on a cylindrical surface to a lysk). At the same time the plug will weaken and will easily be removed from a half shaft.
2. It is possible to remove the plug together with the bearing on a hydraulic press. For this purpose between a plate 3 fastenings of the bearing and the bearing insert the plates 4-5 mm thick or special half rings covering and the bearing. Operev these half rings on a support or to a press traverse, a press rod from the shlitsevy end to a vypressuyta a half shaft.

       PREVENTION
Reuse of the locking plug is not allowed.

3. Remove a plate of a half shaft and the persistent plug.
Assembly of a half shaft
1. Put a half shaft vertically.
2. Install on a half shaft the persistent plug 2 (see fig. 3.65) and a plate 3 half shafts.
3. Put on the bearing a half shaft and press it against the stop in the persistent plug.
4. Heat the locking plug 7 to temperature of 250-300 °C. At such temperature colors of a pobezhalost appear (blue and violet).
5. Put on the locking plug a half shaft. The big facet on the external surface of the plug has to be turned towards shliyets.
6. Napressuyte the locking plug on a half shaft against the stop, using for this purpose a pipe with perpendicularly the cut end face with a diameter of opening of 30,5-32 mm and 555-650 mm long.

       NOTE
You carry out dismantling of a reducer at the special stand or adaptation. If they are absent, then dismantling and assembly can be executed with use of the device fixing a bridge beam in a motionless state.

Dismantling of a reducer of the back bridge
1. Uncover the 36th reducer, having turned off bolts of its fastening.
2. Turn off bolts and remove stoppers of adjusting nuts of bearings of differential. Mark covers of bearings of differential as they are not interchanged.
3. Turn off bolts of fastening of a cover of bearings of differential and uncover.
4. Take out adjusting nuts and differential with the conducted gear wheel and bearings.
5. Turn off a nut of fastening of a flange to a shaft of the leading gear wheel.

Fig. 3.68. Removal of a flange of fastening of the driveshaft


6. A stripper remove a flange of fastening of the driveshaft (fig. 3.68).
7. The rubber or wooden hammer beat out the leading gear wheel with an internal ring of the back bearing and the expansion plug, holding at the same time with a hand a gear wheel for a head.

Fig. 3.69. Vypressovka of an external ring of the forward bearing: 1 – support; 2 – mandrel


Fig. 3.70. A support under a case of the main transfer at a vypressovka of an external ring of the forward bearing. End faces And yes In have to be parallel


8. Establish a case on a special support of 1 (fig. 3.69) by a mouth down and by means of a mandrel to 2 vypressuyta an external ring of the forward bearing along with a maslootrazhatelny washer and a cuff of the leading gear wheel. The sizes of a mandrel are shown in fig. 3.70.

Fig. 3.71. Vypressovka of an external ring of the back bearing: 1 – mandrel; 2 – bearing ring


9. Vypressuyte an external ring of 2 (fig. 3.71) of the back bearing by means of the special, entered through the same ring mandrel 1 also take out adjusting laying.

Fig. 3.72. Removal of an internal ring of the back bearing from the leading gear wheel: 1 – ring; 2 – a glass from two semi-cylinders; 3 – the gear wheel is leading; 4 – internal ring of the bearing


10. Remove the expansion plug from the leading gear wheel. Remove an internal ring of 4 (fig. 3.72) of the back bearing on a manual press, using the special support consisting of two semi-cylinders connected by a ring 1.
Dismantling of differential

Fig. 3.73. Removal of the bearing of differential


1. Remove differential bearings by means of a stripper (fig. 3.73).
2. Fix differential with the conducted gear wheel in a vice. Turn off and remove bolts of fastening of the conducted gear wheel.
3. Easy blows of the wooden or rubber hammer remove the conducted gear wheel 12 (see fig. 3.65) from a differential box.

Fig. 3.74. Vypressovka of a satellite axis: 1 – metal core; 2 – satellites; 3 – differential box; 4 – finger of satellites


4. By means of a metal core beat out a finger of satellites (fig. 3.74) from a box.
5. Turn gear wheels of 31 half shafts (see fig. 3.65) and satellites 34 so that the last were rolled out from a differential case window.
6. Take out from the case of differential of a gear wheel of 31 half shafts with persistent washers 23.
Check and repair of details of a reducer
1. Before survey of a detail of a reducer carefully wash up to facilitate detection of defects and wear.
2. Check whether is not present on teeths of gear wheels of damage or the increased wear, whether contact spots on a working surface of teeths are correctly located. At detection of the increased wear, incomplete gearing of teeths or the painted teeths replace gear wheels. The conducting and conducted gear wheels are replaced only in a set as in the course of production they are selected in pairs for noise and a spot of contact.
3. Check the surfaces of necks of semi-axial gear wheels, vents, seats in the differential case.
4. Check a condition of surfaces of an axis of satellites, seats in the case of differential, an opening of satellites, basic surfaces. At insignificant damages polish with a fine-grained skin, at serious defects replace details new.
5. Examine bearings of the leading gear wheel and cases of differential. They have to be without wear signs, with smooth working surfaces.
6. Replace bearings at the slightest doubt in their working capacity. Defective bearings can be the cause of noise and jamming of teeths.
7. Check a case of the back bridge, the differential case for existence of deformations and cracks. Replace defective parts.
Assembly of differential
1. Dip gear wheels of half shafts and satellites into engine oil.
2. Install in the differential case semi-axial gear wheels with persistent washers.
3. Install satellites in the case and turn half shaft gear wheels with satellites so that the axis of rotation of satellites coincided with the corresponding openings in the case.
4. Implant a finger of satellites.

Fig. 3.75. A persistent washer under a half shaft gear wheel


5. Check an axial side play of gear wheels of a half shaft. Admissible axial side play of 0,3 mm. At emergence of a bigger gap enclose additional persistent washers (fig. 3.75) under half shaft gear wheels. In order to avoid an overload adjustment of gear wheels of half shafts has to be identical.
6. After assembly of differential of a gear wheel no more than 20 N · m have to rotate from effort (2,0 kgfs · м).
Assembly and adjustment of a reducer
Durability and noiselessness of work of the back bridge in many respects depend on the correct and accurate assembly and adjustment of a reducer. At assembly have to be provided:
– the correct interposition of gear wheels of the main transfer and installation of the leading gear wheel by the assembly size C (see fig. 3.65);
– a necessary side gap between teeths of the leader and conducted gear wheels;
– preliminary tightness of bearings of the leading gear wheel.
Key parameters of adjustments of a reducer
The assembly size C – distance from an end face of the leading gear wheel to a differential axis – is theoretically equal to 53,4 mm.
However at selection of couple on the control machine for ensuring the correct contact of teeths the conducted and conducting gear wheels should be moved along their axes. Thus the theoretical assembly size is broken, and its first amendment is made.
Besides, height of a head of the leading gear wheel happens various (within the admission) therefore after its measurement the second amendment is made.
The sum of these two amendments (deviations) registers the electrocount at end faces of the leader and conducted gear wheels as the general amendment to the theoretical size C.
If the amendment is faced by the sign "+", then it needs to be subtracted from the size of 53,4 mm if "-" – to add. The received result will be the nominal assembly size. A tolerance from this size at assembly of a reducer +0,02 … –0,05 mm.
The side gap between teeths of the leader and the conducted gear wheels is necessary for compensation of errors when processing teeths, the temperature changes arising in the course of work of knot and for the correct arrangement of a spot of contact of teeths.

Fig. 3.76. Check of a side gap in gearing of teeths of the leader and the main transfer conducted gear wheels by means of the indicator


For gear wheels of the main transfer the side gap measured on a normal to a profile of tooth of the conducted gear wheel (fig. 3.76) has to be 0,10–0,22 mm, however for each separately taken couple the difference between the greatest and smallest gap should not exceed 0,08 mm. Increase in a gap has to be smooth, the difference of side gaps two a number of the located teeths should not exceed 0,03 mm.

Fig. 3.77. Check of a preliminary tightness of bearings of the leading gear wheel


The preliminary tightness of bearings (fig. 3.77) of the leading gear wheel is created by the axial loading arising at an inhaling of a nut of the leading gear wheel and regulated by means of the expansion plug and the moment of an inhaling of a nut of the leading gear wheel.

Fig. 3.78. Control device for check of the moment of friction (shift) of bearings of the leading gear wheel of the main transfer


Fig. 3.79. A mandrel for a napressovka of an internal ring of the back bearing on a shaft of the leading gear wheel of the main transfer: 1 – mandrel; 2 – bearing ring; 3 – leading gear wheel


The size of a preliminary tightness is determined by the friction moment in bearings (after a final inhaling) which has to make 1,5–2,5 N · m (0,15–0,25 kgfs · м). Measure the moment of friction by means of special adaptation (fig. 3.78) after scrolling of the leading gear wheel on 10-15 of the turns necessary for release of working surfaces of bearings from conservation lubricant and acquisition of the working condition by them. The sizes of a mandrel of adaptation are shown in fig. 3.79. In the absence of adaptation the moment of friction can be checked, turning a hand a flange: at the same time some resistance to rotation which is not causing the excessive tension of a hand has to be felt.
The increased preliminary tightness can lead to jamming and the increased wear. The axial side play of the leading gear wheel appears from behind an insufficient preliminary tightness, gearing of couple worsens, teeths wear out, the gnash at the movement of the car appears a setup.
Installation of the leading gear wheel
1. Press by means of a mandrel (see fig. 3.79) an external ring of the back bearing in a reducer case under a press or blows of the hammer.
2. Napressuyte an internal ring of 2 (fig. 3.79) of the back bearing on the leading gear wheel 3 by means of a mandrel 1 under a press or blows of the hammer.

Fig. 3.81. A mandrel for centering of a shaft of the leading gear wheel of the main transfer


3. Insert the leading gear wheel collected with an internal ring of the bearing into a case (fig. 3.80), put on a mandrel (fig. 3.81) and establish a case at the stand with an emphasis of an end face of the leading gear wheel on a support with a copper or bronze tip. Napressuyte a flange by means of a mandrel (see fig. 3.79) and the hammer, put on a washer and tighten a nut, having chosen as that an axial side play of the leading gear wheel.

Fig. 3.82. A special control mandrel and a micrometric rack for measurement of the assembly size in a case of the main transfer: and – a control mandrel; – a micrometric rack


4. Insert a control mandrel 1 (see fig. 3.80) into nests of bearings of differential. The sizes of a control mandrel are shown in fig. 3.82, and. Establish according to tags of a cover of bearings on the places and tighten bolts.
5. By means of a micrometric rack 2 (see fig. 3.80) measure distance in to a control mandrel.
6. Remove a control mandrel, a vypressuyta an external ring of the back bearing.
7. Calculate thickness of T of a package of adjusting laying which needs to be established in a reducer case under an external ring of the back bearing on a formula
T = (and + in) – With, where
and – a half of diameter of a control mandrel, mm;
in – the distance from a control mandrel to an end face of the leading gear wheel measured by a micrometric rack, mm;
With – the nominal assembly size of couple of gear wheels of the main transfer, mm (it is detailed see. "Key parameters of adjustments of a reducer").
8. Install the picked-up package of laying in a case and again press an external ring of the back bearing.
9. Press an external ring of the forward bearing in a case.
10. Insert into a case the leading gear wheel with established on it by an internal ring of the back bearing and the expansion plug. Napressuyte an internal ring of the forward bearing also put on a maslootrazhatelny washer.

Fig. 3.83. A mandrel for a press fitting of a cuff of the conducting gear wheel in a mouth of a case of the main transfer


11. Dip a cuff of the leading gear wheel into oil and by means of a mandrel (fig. 3.83) press it against the stop, and the spring of a cuff has to be from the inside of a case.
12. Napressuyte a flange of fastening of the driveshaft, put on a washer and tighten a nut before receiving the moment of friction in bearings of 2,5-3,4 N · m (0,25–0,35 kgfs · м). Zakernite a nut.
Installation of the conducted gear wheel and bearings of differential
1. Napressuyte the conducted gear wheel on the differential case by means of the wooden or rubber hammer. For combination of openings in the case with carving openings of a gear wheel screw several hairpins in carving openings. They can be made of bolts, having sawn round heads.
2. Wrap bolts of fastening of the conducted gear wheel the moment of 49-69 N · m (5–7 kgfs · м).

Fig. 3.84. A mandrel for a press fitting of bearings of differential


Fig. 3.85. Napressovka of differential bearings: 1 – differential; 2 – bearing; 3 – mandrel


3. By means of a mandrel (fig. 3.84) to a napressuyta bearings of differential (fig. 3.85).
Adjustment of bearings, differential and side gap of the main transfer
1. Establish differential in case nests with the minimum, hardly notable side gap between teeths of the leader and conducted gear wheels.
2. Establish adjusting nuts closer to differential bearings, put covers of bearings and wrap bolts the preliminary moment of 47-49 N · m (4,8–6 kgfs · м).
3. By means of the indicator fixed in a rack check a beating of an end face of the conducted gear wheel. Admissible beating of 0,08 mm. If the beating is more, find out and remove the cause of excess (smooth out zaboina, agnails, tighten adjusting nuts).
4. Wrap an adjusting nut a special key from the conducted gear wheel before receiving a side gap of 0,08-0,10 mm, at the same time the opposite adjusting nut should not concern an external ring of the bearing. Measure a side gap in gearing by means of the indicator fixed in a rack. The leg of the indicator has to settle down in the radial direction to the surface of tooth (see fig. 3.76).
5. Tighten an opposite adjusting nut before receiving a side gap of 0,15-0,17 mm on the same tooth (in detail see. "Key parameters of adjustments of a reducer").
6. Tighten bolts of covers of bearings the moment of 67-73 N · m (6,8–7,5 kgfs · l) also check a side gap. If necessary repeat adjustment.
7. Establish and fix by bolts stoppers of adjusting nuts.
8. Establish cardboard laying and tighten a case cover. It is desirable to dip bolts of fastening of a cover for sealing of carving openings into paint from aluminum powder.