7.1. Working brake system

On all wheels of cars kolodochny brake mechanisms are installed. Forward brake mechanisms structurally differ from back. Forward brake mechanisms of cars with bridges with final drives differ in the boards having other pimple, a complete set of brake cylinders and connecting tubes of cylinders, and also working position of cylinders. Back brake mechanisms of these cars differ only in boards.

Fig. 6.1. Brake mechanism of a forward wheel: and – tags on basic fingers; 1 – board; 2 – connecting tube; 3 – wheel brake cylinder; 4 – perepusknoy valve; 5 – connecting coupling; 6 – coupling spring of blocks; 7 – overlay of a block; 8 – brake block; 9 – protective cap; 10 – piston; 11 – sealing rings; 12 – piston spring; 13 – adjusting clown; 14 – basic finger of a block; 15 – nut; 16 – bolt of the connecting coupling; 17 – laying; 18 – basic plug; 19 – bolt of the adjusting clown; 20 – washer


Fig. 6.2. Brake mechanism of a back wheel: and – tags on basic fingers; 1 – basic finger; 2 – board; 3 – clown; 4 – head of an axis of the clown; 5 – wheel brake cylinder; 6 – perepuskny valve;
7, 13 – brake shoes; 8 – protective cap; 9 – piston; 10 – sealing rings; 11 – piston spring; 12 – coupling spring


The basic device of brake mechanisms of forward and back wheels is shown in fig. 6.1 and 6.2.

Fig. 6.3. Drive of the working brake system of cars of family UAZ-31512: 1 – signaling device; 2 – switch of an alarm lamp of critical condition of a hydraulic actuator of the brake system; 3 – tanks; 4 – case of the main brake cylinder; 5, 8 – nuts; 6 – vacuum amplifier; 7 – plate; 9 – pedal axis; 10 – fork; 11 – finger; 12 – pedal; 13 – emphasis; 14 – braking signal switch; 15 – ottyazhny spring; 16 – arm


Fig. 6.5. Vacuum amplifier: 1 – cover of the secondary camera; 2 – piston of the secondary camera;
3 – return valve; 4 – spring; 5 – nut; 6 – emphasis; 7 – rod; 8 – washer; 9 – rod sealant; 10,12,37 – lock washers; 11 – sealing ring; 13 – sealing cuff of a cover;
14 – plate of a diaphragm; 15 – the directing cover ring; 16 – cover of primary camera;
17 – basic ring; 18 – diaphragm of the piston of the secondary camera; 19 – connector; 20 – buffer;
21 – spring of a diaphragm of the valve of management; 22 – diaphragm of the piston of primary camera; 23 – case of the amplifier; 24 – piston of primary camera; 25 – valve case; 26 – persistent washer; 27 – the directing case ring; 28 – sealing cuff of the case; 29 – valve piston; 30 – air filter; 31 – protective cover; 32 – pusher fork; 33 – pusher; 34 – spring plug; 35 – valve spring; 36 – sealant of the valve of management; 38 – forelock-provoloka; 39 – valve diaphragm; 40 – screw-upor; I, II – atmospheric cavities; III, IV – vacuum cavities


Fig. 6.6. Main brake cylinder:
1 – cover; 2 – laying; 3 – grid; 4 – tank;
5 – union; 6, 8, 15 – laying; 7 – stopper;
9 – stopper insert; 10 – spring; 11 – spring saddle; 12 – washer; 13,19 – pistons; 14 – persistent bolt; 16 – holder of a spring; 17 – screw emphasis; 18 – sealing cuff; 20 – sealing ring; 21 – persistent washer; 22 – lock ring


Fig. 6.7. Alarm device: 1 – case;
2 – union; 3 – switch; 4, 8 – laying;
5 – stopper; 6 – long piston; 7 – short piston


The drive of the working brake system (fig. 6.3 and 6.4) includes a pedal, the vacuum amplifier (fig. 6.5), the two-chamber main brake cylinder (fig. 6.6), the signaling device (fig. 6.7), pipelines with connecting fittings and wheel cylinders.

Fig. 6.8. Pressure regulator: 1 – piston; 2 – sealing ring of the piston;
3, 6 – basic washers of a spring of the piston; 4 – piston spring; 5 – case; 7 – piston head sealant;
8 – case plug; 9 – basic washer of the plug of a pusher; 10 – pusher plug;
11 – ring sealing pusher; 12 – basic plate; 13 – pusher plug spring; 14 – stopper;
15 – laying of a stopper;
16 – perepuskny valve;
17 – cap; 18 – piston plug; 19 – lock ring; 20 – protective cover



On a part of cars in system of a hydraulic actuator the regulator of pressure (fig. 6.8) which automatically corrects pressure of brake fluid in brake mechanisms of back wheels depending on load of the car can be installed.

Maintenance
Constantly you watch serviceability of the working brake system, in due time you make its adjustment and eliminate the arisen malfunctions.
Systematically check liquid level in tanks of the main brake cylinder and in case of need you bring it to norm. Level has to be 15-20 mm lower than the top edges of bulk openings. You watch tightness of connections of pipelines of a hydraulic actuator. Check a condition of pipelines, reliability of fastening of tubes on a frame and the back bridge. At surveys be convinced of absence of damage of tubes and flexible hoses. Replace the tubes and hoses having damages new.

Fig. 6.9. Pressure regulator drive: and – cars of family UAZ-31512; – cars of family UAZ-3741, UAZ-3962, UAZ-2206, UAZ-3303 and their modifications on cars UAZ-33036, UAZ-39094, UAZ-39095 the regulator is installed from the opposite side of a cross-piece of a frame;
1 – pressure regulator; 2 – arm (basis); 3 – drive lever; 4 – adjusting bolt;
5 – elastic lever; 6, 9, and 13 – bolts; 7 – plug; 8 – lever rack; 10 – the plug is expansion; 11 – plug; 12 – rack arm; 14 – lever axis



At seasonal service check operability of the regulator of pressure. Clear the regulator of dirt and check reliability of its fastening. Be convinced by external survey that the regulator and details of its drive have no damages, there are no dribbles of brake fluid and gaps in connection of a rack with the elastic lever and an arm on the back bridge (fig. 6.9).
By pressing a brake pedal the piston 1 (see fig. 6.8) the regulator of pressure has to start from the case on 1,7–2,3 mm. Lack of a piston stroke, and also its insufficient or excessive course testify to malfunction of the regulator or its drive.
Pay attention at surveys of a hydraulic actuator to an arrangement of a plastic (control) cap 17 and lack of dribble from under it brake fluid. In the normal state the cap has to be drowned in a regulator case opening against the stop. Vystupany caps from an opening and dribble of brake fluid mean loss of tightness of sealing rings 11 and, as a result, operability of the regulator.
As required check reliability of fastening of the vacuum amplifier, wash out or you make replacement of the air filter of the amplifier.
Periodically remove brake drums and clear details of brake mechanisms of dirt. In summertime and when driving on dirty roads you purge more often.
At removal of the brake drum be convinced of lack of a leak from wheel brake cylinders, and also of reliability of fastening of wheel cylinders to boards. Pay attention to a condition of protective caps of wheel cylinders, degree of wear of frictional slips, and also a condition of the brake drum. In case of "oiling" of surfaces of slips smooth out them a grinding skin.
At the removed naves tighten bolts of fastening of brake boards.
Regularly wash out a hydraulic actuator and fill in in it fresh brake fluid. For careful washing of a hydraulic actuator sort main and blow wheel brake cylinders, pressure regulator, and pipelines compressed air.
When dismantling cylinders observe purity. Wash out rubber and metal details of cylinders in pure brake fluid. Do not allow use of kerosene or gasoline as it will cause swelling of rubber details and an exit of the brake system out of operation. During assembly working details of cylinders are recommended to be greased with brake fluid.

Adjustment
And reduction of the course of a pedal regulate restoration of a normal amount of gaps between blocks and brake drums clowns at whom six-sided heads of axes are removed outside through a board.
 You carry out adjustment of gaps between blocks and brake drums (the current adjustment) in the following order:
1. Lift a jack a wheel which brake mechanism needs to be adjusted.
2. Rotating a wheel, gradually turn the adjusting clown until the wheel does not slow down.
3. Gradually release the clown, turning a wheel before free rotation without drum zadevaniye for blocks.
4. Adjust in the same way gaps between blocks and drums of other brake mechanisms.

Fig. 6.10. Adjustment of gaps between blocks and the brake drum of a forward wheel



At adjustment of brake mechanisms of forward wheels and forward blocks of brake mechanisms of back wheels rotate a wheel (fig. 6.10) forward.

Fig. 6.11. Adjustment of gaps between blocks and the brake drum of a back wheel



At adjustment of back blocks of brake mechanisms of back wheels rotate a wheel (fig. 6.11) back.
For reduction of gaps clowns turn in the direction of rotation of a wheel, and for increase – against.
5. Check on the run of the car lack of heating of brake drums and uniformity of operation of brake mechanisms when braking.
At the current adjustment do not use basic fingers as at the same time factory installation of blocks will be broken.
When replacing frictional slips adjust installation of blocks.
You make adjustment of brake mechanisms when brake drums completely cooled down and bearings of wheels are correctly adjusted.
 UAZ – 31512 you make adjustment of a free wheeling of a pedal on family cars change of provision of an emphasis of the switch 14 (see fig. 6.3) a braking signal.

Fig. 6.4. Drive of the working brake system of cars of family UAZ-3741:
1, 20 – arms; 2 – braking signal switch; 3 – nuts; 4 – buffer-upor; 5 – pedal; 6 – intermediate fork; 7 – fork;
8 – lock-nut; 9 – draft; 10 – cover; 11 – intermediate lever; 12 – ottyazhny spring; 13 – switch of an alarm lamp of an emergency condition of brake system; 14 – alarm device; 15 – case of the main brake cylinder; 16 – tanks; 17, 19 – nuts; 18 – vacuum amplifier; 21 – pusher fork



 UAZ – 3741 you make adjustment of a free wheeling of a pedal on family cars by change of length of vertical draft 9 (see fig. 6.4) by means of forks 7, previously having turned off lock-nuts 8.
Check a free wheeling of a pedal at the idle engine.
The free wheeling of a pedal on cars UAZ makes 5–14 mm, considering on its platform.

Filling of a hydraulic actuator of the brake system with liquid and check of operability of system
Filling of a hydraulic actuator you make only special brake fluid as directed tables of greasing in the following order:
1. Check tightness of all connections of a hydraulic actuator and a condition of flexible hoses.
2. Lift a cowl (remove facing of a radiator on the car of family UAZ-3741) and turn off covers of tanks 3 (see fig. 6.3) and 16 (see fig. 6.4) the main cylinder. Fill tanks with brake fluid.

Fig. 6.12. Pumping of the brake system



3. Remove a rubber cap from the perepuskny valve of the brake cylinder of the right back brake mechanism and put on a rubber hose about 400 mm long the valve. Lower other end of a hose in the glass vessel with a capacity not less than 0,5 l filled with brake fluid (fig. 6.12).
4. Unscrew on 1/2–3/4 turns perepuskny the valve then several times press a pedal. Press a pedal quickly, release slowly.
Liquid under pressure of the piston of the main brake cylinder will fill a hydraulic actuator and to force out air. * you make pumping until allocation of vials of air from the hose lowered in a vessel with brake fluid stops. During pumping add brake fluid in tanks of the main brake cylinder, without allowing an exposure of their bottom that air did not get to system again.
During all operation on filling you hold the end of a hose shipped in liquid.
5. Densely wrap at the pressed pedal perepuskny the valve of the wheel cylinder, remove a hose and put on a cap.

* You make pumping of a hydraulic actuator not only when filling with its liquid, but also in case of depressurization of a hydraulic actuator of the working cylinder of back brake mechanisms

6. Make pumping of the brake cylinder of the back left brake mechanism, then regulator of pressure and brake cylinders of forward brake mechanisms. On brake mechanisms of forward wheels the lower, and then top cylinder is pumped over at first.
7. Switch off the signaling device for what make the following:
– unscrew perepuskny the valve of the right or left working cylinder of back brake mechanisms;
– smoothly press a pedal before switching off of an alarm lamp on the dashboard; if the alarm lamp blinks, then it will mean that pistons of a signaling device passed neutral situation and therefore operation should be repeated at first, but only unscrewing perepuskny the valve of a forward wheel;
– wrap the valve at the pressed pedal.
After pumping of all brake mechanisms add liquid in tanks of the main brake cylinder to the level of bulk openings 15-20 mm lower than the top edges.
Densely wrap covers.

Note
Do not add the liquid collected in a glass vessel when pumping in the main brake cylinder.

If brake fluid in system dirty, merge it and fill system with fresh liquid. Do not press a pedal at the removed brake drum as under pressure in a hydraulic actuator pistons will be squeezed out of wheel cylinders and liquid will flow out outside.
After filling of system with liquid check the car for braking. At the correct adjustment of working brake mechanisms and correctly executed pumping of a hydraulic actuator full braking has to happen within 1/2–2/3 courses of a pedal then the leg has to feel a "rigid" pedal.

Repair
At emergence in details of the brake system of big wear or other malfunctions sort, check a condition of details and their suitability for further work. Replace the worn-out and damaged details. At repair of system use these tab. 6.1.
Lower brake shoes with the slips which are made oily in the course of work for 20–30 min. in gasoline (unleaded). Then carefully clear working surfaces of slips a metal brush and a skin. At big wear of slips (to heads of rivets there were 0,5 mm) replace them new. When replacing slips their surface to a proshlifuyta so that diameter of slips was 0,2-0,4 mm less than diameter of a drum.
If on the working surface of reels there are deep risks, teases or uneven wear, then chisel a drum. When boring drums be based on external rings of hug bearings. Increase in internal diameter of drums by 0,8 mm after boring does not demand change of diameter of brake shoes.
The most admissible diameter of the chiseled drum of the working brake mechanism – 281 mm.
When dismantling wheel and main brake cylinders and the regulator of pressure observe purity. Wash out rubber and metal details of cylinders only in alcohol or brake fluid. Do not apply kerosene or gasoline as it will put rubber details of the brake system out of action.
After a sink of a detail blow compressed air, but do not wipe fabric in order to avoid hit of fibers on a working surface of details and loss of tightness. Before assembly of a cuff and sealing rings ship in brake fluid.

Removal, dismantling and assembly of working brake mechanisms
At repair brake shoes and wheel cylinders or details entering them for which removal there is no need to remove completely brake mechanisms usually are subject to replacement.
Assembled from the car you make removal of brake mechanisms only at their full replacement new or at full dismantling of bridges.
At installation of brake mechanisms of forward wheels pay attention to the correct provision of a board to the car. The top cylinder has to be inclined forward (from a vertical axis) on a corner about 30 ° (on cars with bridges with final drives cylinders settle down horizontally). Blocks when braking have to be wrung out on the course of rotation of the brake drum at the movement of the car forward. At installation on the car of brake mechanisms of back wheels the block with a long slip has to be ahead.
 You make removal and installation of brake shoes in the following order:
1. Lift a jack the car and remove a wheel which brake shoes need to be removed.
2. Remove the brake drum from a nave. For this purpose unscrew three screws of fastening of a drum to a nave. If the drum is removed hardly, then wrap removable bolts in three special carving openings which are available in a disk and, evenly wrapping them, remove a drum.

Fig. 6.13. Removal and installation of a coupling spring of brake shoes


3. Remove a coupling spring of brake shoes by means of special nippers (fig. 6.13).
4. Remove the top cups of squeezing springs, springs, the lower cups and take out cores.
5. Turn off nuts of basic fingers, take out basic fingers, clowns and remove brake shoes.
And assembly of brake mechanisms you make installation of blocks with new slips upside-down.
Brake drums are processed together with naves therefore after removal establish them on the same naves. Shift of brake drums from one nave on another will lead to increase in a beating of working surfaces of the reel of rather brake slips.
At installation of the reel into place before wrapping screws, it is necessary to press densely nuts of fastening of wheels the brake drum to a nave and only after that to wrap screws. It is necessary for more dense pressing of the brake drum to a wheel nave.
 You make adjustment of installation of brake shoes in the following order:
1. Lift a jack a wheel which brake mechanism needs to be adjusted.
2. Turn off nuts of basic fingers a little and establish basic fingers in initial situation (tags at end faces of basic fingers have to be located as it is specified fig. 6.1 and 6.2).

Fig. 6.14. Adjustment of brake blocks of a back wheel basic fingers



3. Pressing a pedal with constant effort 118–147 N (12–15 kgfs), turn basic fingers so that the ends of blocks from fingers rested against the brake drum (fig. 6.14). Determine the moment of contact of blocks with a drum by increase in resistance when turning a basic finger. In this situation tighten nuts of basic fingers, watching that at the same time fingers did not turn.
4. Turn adjusting clowns against the stop of blocks in the brake drum until the wheel slows down.
5. Having stopped pressing a pedal, turn adjusting clowns in the opposite direction so that wheels rotated freely, without drum zadevaniye for blocks.
At the correct installation of new blocks with not worn-out brake drums of a tag "and" on basic fingers have to be located, as shown in fig. 6.1 and 6.2 or with deviations from this situation in this or that party to 50 °.
At installation of new blocks when frictional slips are not earned extra to the surface of reels yet, brake drums after the specified adjustment can heat up a little. After several braking of a block will be earned extra, and heating will stop. At strong heating of brake drums take away blocks from the brake drum adjusting clowns a little.
 You make removal and dismantling of wheel brake cylinders in the following order:
1. Disconnect the pipeline from the cylinder and remove the cylinder.
2. Take off protective caps of cylinders, take out pistons with sealing rings and springs.
 You make assembly and installation of wheel brake cylinders upside-down.
 You make removal and dismantling of the main brake cylinder in the following order:
1. Disconnect the pipelines conducting from the main brake cylinder to the signaling device.
2. Disconnect the signaling device from the main brake cylinder.
3. Disconnect the main brake cylinder from the vacuum amplifier.
4. Turn off a persistent bolt 14 (see fig. 6.6).
5. Remove a lock ring 22 and take out a persistent washer 21.
6. Take out the piston of primary camera assembled 19.
7. Turn off a stopper 7, take out an insert of a stopper 9, a returnable spring 10 and the piston of the secondary camera assembled 13.
Tanks 4 are not recommended to be removed without need. In case of need for their removal turn off traffic jams of tanks 1, remove grids 3 and unscrew unions 5 of fastening of cases of tanks.
Assembled 19 take out the piston only towards a flange, and the piston assembled 13 – towards an opposite end face. Take out pistons carefully not to damage sealing cuffs 18 and rings 20. If pistons are not taken out freely from the cylinder, at first slightly push the piston 13 the piston 19, and then carefully push out the piston 19 pressing (through the released cavity) the screw-driver or other subject on the holder of a spring 16 or the screw of the holder of a spring 17.
You make assembly and installation of the main cylinder upside-down. At the same time install assembled pistons in the cylinder carefully and only from the torets of the cylinder corresponding to them. In order to avoid damage of sealing cuffs and rings do not push pistons through all cavity of the cylinder.
At assembly of the piston 19 wrap the screw 17 against the stop in the piston. 14 wrap a persistent bolt in a case only after installation of the assembled piston 19, a washer 21 and a lock ring 22.
 Inhaling moments:
persistent bolt 14..... 8–10 N · m (0,8–1,0 kgfs · l);
union 5..... 16–22 N · m (1,6–2,2 kgfs · l);
traffic jams 7..... 167-186H · m (17–19 kgfs · м).

 You make removal and dismantling of the regulator of pressure in the following order:
1. Disconnect the pipelines conducting to the regulator.
2. Disconnect the regulator from an arm (basis).
3. Turn off a stopper 14 (see fig. 6.8) from a case end face.
4. Remove a protective cover 20 and a lock ring 19.
5. Take out the piston 1 of the case with all internal details.
6. Unscrew perepuskny the valve 16.
The control cap 17 is not recommended to be removed without need. Take out the piston from the case carefully towards an end face under a protective cover not to damage sealing rings. If the piston is not taken out freely from the case, at first slightly push him from an end face under a stopper.
You make assembly and installation of the regulator in the following order:
1. Collect the piston 1 with a sealant 7 (see fig. 6.8).
2. Install in the regulator 5 case the case plug 8, the subassembled piston with a sealant, a basic washer 6, a spring 4 pistons, a basic washer 3, a sealing ring 2, the plug 18 of the piston and a lock ring 19.
3. Install in the regulator case a basic washer 9, a sealing ring 11, the pusher plug 10, the second sealing ring 11, a basic plate 12 and a spring of the 13th plug.
4. Podsoberite a stopper 14 with laying 15 also wrap it in the regulator case.
5. Wrap in the case of the regulator perepuskny the valve 16.
6. Establish a protective cover 20, a cap of the perepuskny valve and a control cap 17 (if it was taken out).
 Inhaling moments:
traffic jams 14..... 43–57 N · m (4,4–5,8 kgfs · l);
valve 16..... 10–14 N · m (1,0–1,4 kgfs · м).

Removal and installation of the drive of the regulator of pressure. The drive of the regulator of pressure is not recommended to be removed without need from the car not to break its adjustment. In case of dismantle at assembly it is necessary to sustain the adjusting sizes given on fig. 6.9. At the same time install the size N (position of the elastic lever 5 concerning an arm 2) by an adjusting bolt 4 on pressure regulator subassembled with an arm 2, the drive 3 lever, the elastic lever 5 and the plug 11 (before installation on the car).
 Inhaling moments:
bolt 13 and nuts of bolts 4, 13 and axes 14........ 27–35 N · m (2,8–3,6 kgfs · l);
bolts of fastening of the regulator to an arm 2 and nuts of a bolt 9........ 14–18 N · m (1,4–1,8 kgfs · l);
nuts of a bolt 6........ 6,4–8,0 N · m (0,65–0,8 kgfs · м).

Removal, dismantling and assembly of the vacuum amplifier
At an exit of the amplifier out of operation on pistons of the main cylinder only the effort from the driver's leg is transmitted through a pusher 33 (see fig. 6.5), the valve of management, the buffer 20 and a rod 7.
The increased size of effort to a pedal indicates the need of survey and, perhaps, repair of the amplifier.
At failure of sealants, springs and other details the amplifier remove from the car, having disconnected previously from it the main brake cylinder, a hose, a pedal and sort. Before dismantling put tags on the case and a cover that at assembly to establish them on the initial places.
Sort and collect the amplifier in special adaptation by means of a small press.
The amplifier establish by four bolts with the rubber plugs which are put on them for protection of a carving from damage in openings of not movably established plate. On two bolts of a cover of the secondary camera, having also protected previously their carving, install the special lever with openings under these bolts and, pressing on it with small effort a press, turn a cover before combination of ledges on the case of the amplifier with hollows on a cover.
Other operations do not demand special devices.
At assembly 6,17, 24, 25 and the contacting surfaces of a cover 1 with a diaphragm 18 grease the working surfaces of friction of details with TsIATIM-221 lubricant.
After assembly the amplifier check for working capacity and tightness. For this purpose attach a hose to the backpressure valve and at the working engine make effort of 196-294 N (20–30 kgfs) for a pusher 33. At the same time the case of the valve of management together with a pusher has to move against the stop.
After removal of effort from a pusher the 33rd case of the valve of management has to come back to a starting position. After 2–3 min. after an engine stop when pressing a pusher 33 hissing of the air arriving in the amplifier via the valve of management has to be listened.
Before installation of the main brake cylinder on the amplifier adjust a departure of a rod of the 7th rather privalochny plane of a cover 1 at a size of 7,78 – 8 mm and a departure of a pusher of the 33rd rather privalochny plane of the case 23 at a size of 134,7 – 136,3 mm.