The main brake cylinder is intended for use in the brake system with diagonal division of contours. In the main brake cylinder there are two pistons, on one on each contour, and it is equipped with the sensor of low level of brake fluid and the regulator of pressure.

By pressing a brake pedal pressure of liquid is distributed evenly between the piston and a bottom of the brake cylinder. Pressure attached to the piston is transferred to the cylinder of a support and presses a brake shoe to an internal surface of a brake disk. Pressure attached to a bottom of the brake cylinder of a support forces a support to slide and move on the directing fingers. As the support moves as a unit, an external part of a support begins to press on an external brake shoe, pressing it to an external surface of a brake disk. In process of increase in pressure force with which blocks press brake slips to a brake disk increases that leads to a car stop. After release of a pedal of a brake pressure in the brake pipeline decreases, and due to elasticity of the sealing ring which is in a flute, the piston departs a little back that leads to reduction of the brake effort enclosed to a brake disk. Wear of overlays of brake shoes is automatically compensated by movement of a support.

The brake mechanism of back wheels of drum type from the leader and conducted by brake shoes. At such design of brakes the top coupling spring presses both brake shoes to the working brake cylinder, and the lower coupling spring presses them to a motionless emphasis. When pressing a brake pedal the piston of the working brake cylinder presses both brake shoes to the internal surface of the brake drum. Friction force creates torque which at the movement of the car forward, presses the leading block to the brake drum even stronger.

At the movement of the car back the similar effect happens to the conducted brake shoe. At such design of a brake there is an automatic adjustment of a gap after a brake pedal otpuskaniye. Besides, at such design brake overlays of the leading block usually wear out quicker, than at the conducted block. If brakes were operated, then to interchange the position of blocks inadmissibly as at the same time the effect of automatic increase in brake effort can be broken that will lead to the increased brake pedal course.

Valves of the regulator of pressure limit pressure transferred to working cylinders of brakes of back wheels after pressure on the main brake cylinder reaches a certain size. They are necessary for regulation of pressure in cylinders of back brakes concerning load of a back axis. Such regulators are usually used in the brake system using a combination of disk and drum brakes.

The main brake cylinder is supplied with the sensor of emergency level of brake fluid. At lowering of the level of brake fluid this sensor includes a control lamp in combinations of devices. After elimination of the reason the lamp dies away.

Operability of the brake system is checked on dry, pure and rather smooth and flat section of the road. An inspection of the valid overall performance of brakes cannot be carried out at a wet, dirty, slippery condition of a paving when tires have unequal coupling with a roadbed. Check of brakes will yield the wrong results as well in case there is a road bias as car weight is distributed between wheels unevenly, or at an uneven surface when wheels jump on a surface. Check efficiency of braking at various speeds of the movement of the car, by easy and strong pressing a brake pedal, however, avoid jamming of brakes and sliding of tires. Jamming of brakes and sliding of tires are not a sign of good efficiency of braking since at rotation of wheels the brake way will be shorter than when wheels are blocked. Friction force between tires and a paving is more if they rotate, but are slowed strongly down. The design of the brake system prevents jamming of brakes, except for very sharp braking.

It is made because the smallest brake way and the best controllability of the car is reached when there is no blocking of brakes. At sharp braking of the car the feeling of the great efforts used to a brake pedal is possible.

1. Tires.

The unequal surface of contact and force of adhesion of tires with a paving lead to uneven braking, and drawings of a protector on the left and right tires have to be approximately equally worn-out.

2. Loading of the car.

At uneven loading of the car braking of wheels with bigger loading requires bigger effort. Hard loaded car demands application of bigger effort to brakes.

3. Adjustment of wheels.

Bad adjustment of wheels, in particular excessive disorder or convergence, lead to uneven braking.

The brake system of the car is equipped with the control lamp located in a combination of devices. If the ignition key is in situation Start, the control lamp of the brake system has to burn. At return of the ignition key to situation Run the lamp has to go out. The following reasons lead to fire of a control lamp of Brake of the brake system.

1. The switched-on parking brake. If the parking brake is switched on, and the ignition key is in situation On, the control lamp has to burn.

2. Low level of brake fluid. Low level of liquid in a tank of the main brake cylinder leads to fire of a control lamp of Brake.

At the engine working at idling rotation frequency, and the gear shifting lever which is in neutral situation press and hold with constant effort a brake pedal in the pressed state. If the pedal begins to fail, it speaks about possible leak in the brake system. For confirmation of this assumption examine the brake system. Check liquid level in a tank of the main brake cylinder. Small lowering of the level of liquid in a tank of the main brake cylinder can be result of big wear of brake shoes, sharp lowering of the level of brake fluid demonstrates existence of leaks in the brake system. Leaks in the brake system can be both external, and internal. When checking the brake system small leaks can be not found. If liquid level in a tank of the main brake cylinder normal, check length of a rod of the vacuum amplifier. If length is not adjusted, adjust or replace a rod. Check adjustments of hydraulic and parking brakes.

This check does not guarantee detection of all malfunctions of the main brake cylinder.

1. Check existence of cracks in the case of the main brake cylinder and traces of leak of liquid around the cylinder. Leaks are demonstrated only by availability of liquid in quantity not less drop. The damp condition of a surface of the cylinder is not abnormal.

2. Check lack of jamming of the course of a pusher of a pedal of a brake and correctness of adjustment of length of a rod. If a condition of these elements satisfactory, disassemble the main brake cylinder and check a condition of sealing rings of pistons. They should not be bulked up or extended. The bulked-up or extended sealing rings testify to the bad or polluted brake fluid. If dirt got to brake fluid, all components of the brake system have to be sorted and cleared of dirt. All rubber details have to be replaced, and all pipelines are washed out.

Brake fluid of inappropriate brand, existence in brake fluid of mineral oils or water can lead to boiling of brake fluid or damage of rubber details of the hydraulic drive of the brake system.

Swelling of a sealing ring testifies to an unsatisfactory condition of rubber details of the brake system. Also inflated sealing rings of pistons of the working brake cylinder of a drum brake can testify to it. If it is obvious that rubber details are in an unsatisfactory state, sort system of the hydraulic drive of brakes and wash out details alcohol. Before assembly dry all details dry compressed air in order that alcohol did not get to hydraulic system of brakes. Replace all rubber details of the hydraulic drive, including brake hoses. During the work with brakes check availability of brake fluid on overlays of brake shoes. If slips are strongly polluted by brake fluid, replace them.

If consolidations of pistons of the main brake cylinder are in satisfactory condition, check for existence of leak of brake fluid or excessive heating of the main brake cylinder. If these symptoms are present, merge liquid from the brake system, wash out the hydraulic drive fresh brake fluid, fill with brake fluid and pump over the hydraulic drive of the brake system.

When replacing the sensor of a stoplight do not increase pusher length for adjustment of the sensor. Length of a pusher is regulated according to other requirements. See the head "The vacuum amplifier of brakes".

       PREVENTION

If for adjustment of operation of the sensor of a stoplight to use adjustment of length of a pusher of a pedal of a brake, then the pusher can drop out that will lead to full failure of the hydraulic drive of the brake system.

For adjustment of the sensor of a stoplight the design of the sensor provided own step-by-step adjustment. Adjustment of the sensor has to be made during its installation.

1. Disconnect a wire from the negative plug of the rechargeable battery.

2. Remove the decorative panel.

3. Disconnect the socket from the stoplight sensor.

4. Remove the stoplight sensor. Turn the sensor on 90 ° and take from an arm.

1. Install the stoplight sensor in an arm, turn on 90 ° for fixing.

2. Connect the stoplight sensor socket.

       PREVENTION

Do not regulate operation of the sensor of a stoplight by means of adjustment of length of a pusher.

Press a pedal of a brake and extend a sensor pusher at the maximum length. Release a brake pedal. The stoplight sensor is adjusted now.

3. Install the decorative panel.

4. Connect a wire to the negative plug of the rechargeable battery.

Check correctness of operation of the sensor of a stoplight. If necessary repeat adjustment.

       NOTE

Do not use the liquids containing oil products. Do not use for storage of brake fluid of capacity in which liquids on the basis of oil products, or the capacities containing the water remains were stored. Liquids on the basis of oil products lead to swelling and violation of a form of rubber details of the hydraulic drive of the brake system. Hit of water in brake fluid leads to fall of temperature of its boiling, hold all containers with brake fluid closed for prevention of its pollution.

For prevention of hit of moisture and air in the hydraulic drive of the brake system and existence of a sufficient reserve of brake fluid it is necessary to watch liquid level in a tank of the main brake cylinder. However in order to avoid overflow of a tank as a result of expansion of liquid when heating from brake cylinders and the engine do not pour too much liquid in a tank. The tank of the main brake cylinder is located on the cylinder in the left forward side of a motor compartment of the car. Before removal of a tank carefully clear it of dirt in order to avoid hit of dirt in a tank. Uncover. Add liquid to tag level on outer side of a tank. Use brake fluid for the hydraulic drive of brakes (Hydraulic Brake Fluid) or similar. Quality of liquid has to correspond to DOT 3.

At hit of air in the hydraulic drive of the brake system it needs to be removed, having pumped over brakes. If air got to the hydraulic drive because of the low level of liquid in a tank of the main brake cylinder or at a detachment of pipelines from the main brake cylinder, then pumping of all four brake cylinders can be required. If the pipeline was disconnected only from one brake cylinder, then it is necessary to pump over only this cylinder. If the pipeline was disconnected in any place between the main brake cylinder and the working brake cylinder, then it is necessary to pump over those brake cylinders which are served by the disconnected part of the brake pipeline.

If the brake system is equipped by the vacuum amplifier, several pressing a brake pedal at the switched-off engine level pressure in the vacuum chamber.

1. Fill a tank of the main brake cylinder with brake fluid and support him, at least, half filled during all operation on pumping of brakes.

2. If there is a suspicion about availability of air in the main brake cylinder, then it needs to be pumped over before pumping of brake cylinders of wheels or a support, following the instruction given below.

a) Disconnect forward brake pipelines from the main brake cylinder.

b) Let's brake fluid fill the main cylinder until it does not begin to pour out from a forward opening, for connection of the brake pipeline.

c) Connect the brake pipeline to a forward opening of the main brake cylinder and tighten a connecting nut.

d) Slowly press a pedal of a brake and hold it in the pressed situation. Weaken fastening of the forward brake pipeline to the main brake cylinder for removal of air from the cylinder. Delay fastening of the pipeline to the cylinder. Slowly release a pedal of a brake and wait for 15 pages. Repeat this sequence of actions, including 15-second pauses until all air is not removed from a cavity of the main brake cylinder. It is necessary to watch that brake fluid did not get on the painted surfaces.

e) After removal of air through forward connection of the brake pipeline repeat the actions given in point of), for removal of air from a back opening for connection of the pipeline to the brake cylinder.

e) If it is known that in supports and brake cylinders of wheels there is no air, then to pump over them there is no need.

3. Pumping of each support and the working brake cylinder of a wheel is carried out only after air is removed from the main brake cylinder.

Fig. 12.1. Pumping of brakes: And – a vessel with brake fluid; In – the tube shipped in brake fluid; With – a key

a) Install a cap key of the corresponding size on the pumping union. Dress a transparent tube which second end freely lower in a transparent vessel with brake fluid (fig. 12.1) on the union.

b) Slowly press a pedal of a brake and hold it in the pressed situation.

Unscrew a few union for removal of air from the cylinder. Tighten again and slowly release a pedal. Wait for 15 pages. Repeat actions in this sequence, including 15-second pauses until air is not completely removed. It is possible that before full removal of air it is necessary to repeat this operation 10 and more time. By sharp pressing a pedal of a brake there is also an advance of the secondary piston in the main cylinder at which removal of air from the brake system is at a loss.

4. Sequence of pumping:

– right back wheel;

– left forward wheel;

– left back wheel;

– right forward wheel.

5. Check whether the brake pedal springs. If a pedal elastic, repeat all cycle of pumping of brakes.

The equipment for pumping of brakes under pressure has to be diaphragm type. Prevention of hit of air, moisture, mineral oils and other substances polluting brake fluid in the hydraulic drive of the brake system requires existence in the equipment of the rubber diaphragm dividing brake fluid and a source of pressure of air.

1. Connect the adapter of the device of removal of air to the main brake cylinder.

2. Pump up the camera of the device of pumping up to the pressure of 137-172 kPa.

3. Connect the line to the adapter and open the crane.

4. Lift the car on convenient height and fix it on support.

5. Dress a hose for removal of pressure upon the union and lower its opposite end in the pure vessel which is partially filled with brake fluid.

6. Unscrew the union on 1/2–1/4 turns and let's liquid flow down until in it there are no vials of air.

7. Sequence of pumping:

– right back wheel;

– left forward wheel;

– left back wheel;

– right forward wheel.

Check existence of elasticity when pressing a pedal of a brake. For elimination of elasticity repeat completely the procedure of pumping of the brake system.

       PREVENTION

After pumping of the brake system the tank with brake fluid can remain under pressure. For protection of the painted surfaces and the mechanic against contact with brake fluid at a detachment of a hose, the device for pumping of brakes, or when unscrewing the adapter of the device cover connection and the adapter with technical fabric.

Fig. 12.2. Scheme of the hydraulic drive of the brake system: 1 – hollow perepuskny bolt; 2 – washer; 3 – support of the right forward brake; 4 – brake pipeline; 5 – main brake cylinder; 6 – brake hose of a back right wheel; 7 – brake drum of the right back brake; 8 – assembly clips; 9 – brake hose of a back left wheel; 10 – brake drum of the left back brake; 11 – lock bracket; 12 – support of the left forward brake; 13 – brake hose of a forward left wheel; 14 – brake hose of a forward wheel

Every time when replacing details of the brake system is recommended to wash out completely and carefully the hydraulic drive of the brake system pure brake fluid (fig. 12.2). Washing of the hydraulic drive of system requires about 1,2 l of brake fluid. If there is the slightest suspicion that in system there is a liquid of inappropriate type or brake fluid contains even insignificant traces of mineral oils, the system of the hydraulic drive of brakes needs to be washed out. All rubber details of the brake system which adjoined to the suspected brake fluid need to be replaced.

       PREVENTION

Never use copper pipelines since copper is subject to fatigue cracking and corrosion that can lead to refusal of brakes. Use steel pipelines with the double thickness of walls.

For check of proportional valves use two manometers for measurement of pressure in system of the hydraulic drive of brakes. Measure pressure at the same time on diagonal on forward and back axes.

1. Remove the union and connect the manometer to the brake cylinder of one of back wheels.

2. Remove the union and connect the manometer to the cylinder diagonalno of the located forward wheel.

3. Pump up pressure in the hydraulic drive of the brake system, several times having intensively pressed a brake pedal. Pressure in the brake system is not regulated, and manometers will show real-life pressure.

4. Increase pressure to achievement of the sizes specified in table 6.1.

       PREVENTION

If pressure exceeds 10 000 kPa, indications of the manometer on the back brake cylinder can be neverny.5. Remove manometers from the checked contour and establish on the second contour. Repeat check for the second contour.

It is necessary to check hoses of the hydraulic drive of the brake system at least, than two times a year. The knot of brake hoses looks round on existence of damage because of driving on bad roads, existence of cracks and attritions of an external cover, swellings and leakages. Check correctness of situation and fastening of hoses. The brake hose which rubs against a suspension bracket detail wears out and eventually will fail. For survey of a condition of hoses the lamp and a mirror can be required. If at survey one of the listed above malfunctions is found, eliminate it or if necessary replace a hose.

1. Lift the car.

2. Disconnect the brake pipeline from an arm of fastening of the left hose.

3. Disconnect an arm of fastening of a brake hose with a hose from a wheel arch arm.

Fig. 12.3. Brake hose of a forward brake: 1 – hollow perepuskny bolt; 2 – washer; 3 – support of the right forward brake; 4 – lock bracket; 5 – brake pipeline; 6 – brake hose of a forward wheel

4. Turn out perepuskny a bolt of 1 (fig. 12.3) from a support 3 and remove sealing rings and a brake hose.

1. Disconnect the brake pipeline from a brake hose.

2. Remove a lock bracket.

3. Disconnect a brake hose from an arm.

4. Turn out perepuskny a bolt from a support, remove sealing rings and a brake hose.

1. Connect a new brake hose to a support with installation of new sealing rings on perepuskny a bolt and tighten a bolt the moment of 40 N • m.

2. Connect the left brake hose to an assembly bracket to an assembly arm on the left mudguard and tighten its moment 8 N • m.

3. Connect the brake pipeline to a brake hose and tighten its moment 11 N • m.

4. Connect the right brake hose to a bracket on the amplifier of a body, at the same time pay attention to lysk to hose tube surfaces.

5. Establish a lock bracket.

6. Connect the brake pipeline to a brake hose and tighten its moment 11 N • m.

7. Lower the car.

8. Pump over the brake system.

9. Check existence of leaks in the brake system.

1. Lift the car.

2. Disconnect brake pipelines from a brake hose.

Fig. 12.4. Brake hose of a back brake: 1 – brake pipeline; 2 – brake hose; 3 – lock bracket; 4 – bracket

3. Remove both lock brackets of 3 (fig. 12.4).

4. Remove a brake hose 2 from a bracket 4.

1. Establish a new brake hose of a lyskama in the flattened part of a bracket. The hose should be inserted lysky into brackets, without overwinding it.

2. Connect the brake pipeline to a brake hose and tighten its moment 11 N • m.

3. Establish lock brackets.

4. Lower the car.

5. Pump over the brake system.

6. Check the brake system for lack of leak of brake fluid.

The following precautionary measures are necessary to protect a carving of a tip of the regulator of a tension of the parking brake at service of the parking brake and cables:

– before to turn off an adjusting nut, clear free strings of a carving of a tip on both sides of a nut of dirt;

– before turn of a nut grease a tip carving.

The procedure of adjustment of the parking brake is provided in the head "Knot of a drum brake".

1. Lift the car.

2. Turn off nuts of fastening of thermal screens of the muffler.

Measure distance from the end of a core of the device of a tension of a cable of the parking brake to a nut.

Fig. 12.5. Parking brake: 1 – lever knot; 2 – cable compensator; 3 – tip plug; 4 – nut; 5 – cable; 6 – clip; 7 – clip; 8 – spring washer

3. Turn off a nut from a core of 4 (fig. 12.5).

4. Remove a locking bracket and the compensator of a cable 2.

5. Remove the rubber fastener from the body bottom.

6. Lower the car.

7. Remove back slips from a sitting sled.

8. Turn off fastening of sitting of the driver from the bottom of a body and remove it.

9. Lift a back rug.

10. Turn out bolts of fastening of the lever of the parking brake.

11. Remove the lever of the parking brake 1 and extend a core from under the car bottom.

Fig. 12.7. Check of an axial beating of a brake disk: 1 – the indicator with a scale; 2 – brake disk of the right forward wheel; 3 – support of a brake of the right forward wheel

12. Turn off and remove the trailer switch 14 (fig. 12.7) of the parking brake from the lever of the parking brake.

1. Attach the trailer switch to the lever of the parking brake and fix by a bolt, having tightened its moment 25 N • m.

2. Fix the lever of the parking brake by bolts to the body bottom, having tightened their moment 20 N • m.

3. Establish into place a rug.

4. Establish sitting of the driver and tighten all fasteners the moment of 20 N • m.

5. Establish a protective cap on the right guide of sitting.

6. Release the lever of the parking brake.

7. Lift the car.

8. Install the rubber fastener on draft and insert it into the car bottom. Check correctness of adjustment.

9. Install a cable of the parking brake on the cable compensator.

Dress a guide of a cable and a locking bracket on a core of the device of adjustment of a tension of the parking brake and screw new самоконтрящуюся a nut on such distance from the end of a core on which there was an old nut before its otvorachivaniye.

10. Check adjustment of the parking brake and if necessary adjust it.

11. Establish the heat-insulating plates.

12. Lower the car.

1. Lower the lever of the parking brake.

2. Raise the car a little and remove back wheels.

3. Remove the brake drum. If necessary for removal of the brake drum through an opening in a basic plate of a brake wring out the lever of the drive of brake shoes.

4. Lift the car.

5. Turn off nuts of fastening of the heat-insulating screen and lower the heat-insulating screen on the muffler.

Fig. 12.6. Lever of the parking brake: 1 – lever; 2 – handle; 3 – button; 4 – spring; 5 – latch; 6 – doggie; 7 – guide; 8 –;;;;; 9 – draft; 10 – bolt; 11 – plug; 12 – bolt; 13 – plug; 14 – trailer switch; 15 – bolt, 25 N • m

6. Remove a cable of the parking brake 5 (see fig. 12.6) from the compensator of a cable 2. Before an otvorachivaniye of the compensator of a cable measure distance from the free end of a midstream of the device of regulation of a tension of a cable.

7. Remove a cable of the parking brake 5 from guides on the body bottom.

8. Remove plastic guides from an arm on the fuel tank.

9. Remove a cable of the parking brake from guides on a beam of the back bridge.

10. The tool with the sharp end remove a locking ring of a cable of the parking brake from the plastic plug on a basic plate.

11. Remove a tip of a cable of the parking brake from the lever of a brake shoe and remove a cable from a brake board.

1. Establish a new cable of the parking brake on a basic plate of a brake and connect it to the lever of a brake shoe.

2. Insert a plastic cover of a cable into a basic plate and fix in a locking ring. Make sure that the cable is located correctly in relation to other details of a suspension bracket.

3. Install brake drums and fix them. If for removal of the brake drum the lever of a block of a brake was wrung out back, wring out it forward and after the end of assembly adjust a tension of the parking brake.

4. Establish a cable of the parking brake 5 (see fig. 12.6) in guides on a beam of the back bridge and insert a plastic cover of a cable into a bracket on the fuel tank.

5. Establish a cable of the parking brake in the bodies directing to the bottom.

6. Install the compensator of a cable of the parking brake and a locking bracket on draft and screw new самоконтрящуюся a nut on such distance from the end of a core on which there was an old nut before its otvorachivaniye.

7. Install the heat-insulating screens.

8. If for removal of the brake drum the lever of a block of a brake was wrung out back, adjust the parking brake.

9. Establish wheels.

10. Lower the car.

Using a wooden or plastic wedge, easy percussions of a kiyanka remove the handle from the lever.

1. Dress the new handle on the lever as it is possible more deeply, at the same time be convinced that the handle is located a figured surface down.

2. Heat the handle hot air from the hair dryer approximately to 70 °C.

3. Pull the handle over the lever to the limiter.

1. Lift the car on the elevator.

2. Note an arrangement of wheels on naves and remove wheels.

3. Examine brake shoes through the top part of a support of a brake regarding:

– insufficient thickness;

– uneven wear.

       PREVENTION

Replacement of blocks has to happen at the same time on both forward wheels.

4. The minimum thickness of a brake shoe together with a slip – 7 mm.

1. Establish wheels and tighten bolts of fastening of disks of wheels.

2. Lower the car

1. Lift the car.

2. Remove a cap from an opening in a brake board for survey of slips. Through openings examine brake overlays for wear existence. Establish a cap into place.

3. If careful survey cannot be made through a viewing opening, remove the brake drum and measure thickness of slips.

The minimum thickness of slips – is 5 mm higher than a head of any of rivets.

       PREVENTION

Replacement of all blocks and overlays of an axis needs to be made at the same time.

4. Install the brake drum and fix it.

5. Insert caps into viewing openings. Tighten bolts of fastening of disks of wheels.

6. Lower the car.

1. Measure thickness of a brake disk in four or more points on a disk circle. All measurements have to be performed at identical distance from edge of a brake disk.

2. If thickness of a brake disk changes at a size more than 0,01 mm, it can cause vibration of a brake pedal and/or forward part of the car when braking. The brake disk which is not meeting these requirements has to be repaired or replaced.

At production the brake disk is exposed to careful check on a deviation from planeness, changes of thickness and axial beats.

For ensuring smooth braking it is necessary to support a condition of a surface of a brake disk according to requirements. It is necessary also for ensuring reliability of work of brakes and extension of service life of brake shoes.

If during operation there are small scratches on a surface of a brake disk which depth does not exceed 0,4 mm, then they do not influence normal work of brakes.

1. Install the gear shifting lever in neutral situation.

2. Lift the car on the elevator.

3. Note the provision of a wheel on a nave and remove a forward wheel.

4. Attach a brake disk to a wheel nave two bolts of fastening of a rim.

5. Fix the indicator with KM-572 scale on a support as it is shown in the figure 12.7.

Install the indicator probe perpendicularly to a surface of a brake disk at distance about 10 mm from an outer edge of a disk, having created small load of the probe.

6. The most admissible axial beating of a brake disk – 0,1 mm.

If the axial beating exceeds the specified value, check whether there is no dirt between a brake disk and a nave and that a surface of a brake disk smooth, without jags.

7. Remove the indicator.

8. Turn out bolts of fastening of a rim. Establish forward wheels and tighten bolts the moment of 90 N • m.

9. Lower the car.

As normal work of disk brakes requires rigid control of a working surface of a brake disk, grinding of its surface has to be carried out only by means of the high-precision equipment.

For all brake disks minimum admissible thickness is specified. This thickness is specified for definition of the most admissible wear of a brake disk, but not for performance of grinding of a surface. Do not use brake disks which do not meet the requirements provided in the specification. At repair of a surface of a brake disk always use the sharp cutting tools.

Blunt or worn-out tools do not provide quality of a surface of a brake disk that influences quality of work of brakes.

At repair of a surface of a brake disk it is always necessary to use devices for clearing of vibrations, such devices will exclude trembling of the tool that will provide the best quality of a surface.

When processing a surface of a brake disk the optimum frequency of rotation of a spindle of the tool – 200 min.-1.

Horizontal giving of the tool at rough processing should not exceed 0,25–0,15 mm / about. At final processing of a surface – no more than 0,05 mm / about.

Every time at removal of their brake drums needs to be cleared carefully of dirt and to examine regarding detection of cracks, deep the protocheck, deviations of an internal surface from round and on existence of biases of an internal surface.

The drum with cracks is unsafe for operation and has to be replaced.

Polish small scratches. Strongly scratched surface of the brake drum results in bystry wear of overlays of brake shoes therefore there can be a need of boring of a surface of the brake drum.

If overlays of brake shoes are worn-out slightly (and can be used and further) and on the surface of the reel there are risks, the surface of the reel needs be not to chiseled, and to polish by means of a fine-grained emery paper. Boring of all flutes of a surface of the reel and grinding of all roughnesses of overlays of brake shoes can demand removal of a thick layer of metal and from a surface of slips. At the same time pro-points and roughnesses can be ground well in and ensure satisfactory functioning of brakes.

If overlays of brakes have to be replaced, then and the surface of the brake drum has to be chiseled. The drum with pro-points when using with new slips not only will result in their bystry wear, but also will make difficult or impossible achievement of good work of brakes.

The drum with an oval or conic surface makes impossible exact adjustment and with a high probability because of the eccentricity results in excessive wear of other details of the brake mechanism.

Besides, ovality of the brake drum can serve as the reason of strong and uneven wear of a protector of tires, and also lead to a brake pedal beating. At excess of ovality/conicity of the brake drum of the limits set in the specification the drum needs to be chiseled. Ovality or conicity of the brake drum can be measured precisely by means of a micrometer for the measurement of internal diameters supplied with a set of extenders.

At measurement of ovality, conicity or wear of the brake drum measurements need to be taken as with internal, and external (closest to edge) the parties of a brake surface, taking measurements lengthways perpendicularly of the located diameters.

Removal of metal of more permitted quantity will influence dispersion by a drum of heat and can cause deformation of a drum.

When boring a drum always use the sharp tool. Blunt or worn-out tools do not provide quality of a surface that influences quality of work of brakes.

At repair of a surface of a brake disk it is always necessary to use devices for clearing of vibrations, such devices will exclude trembling of the tool that will provide the best quality of a surface.

When processing a surface of a brake disk the optimum frequency of rotation of a spindle of the tool – 200 min.-1.

Horizontal giving of the tool at rough processing should not exceed 0,25–0,15 mm / about. At final processing of a surface – no more than 0,05 mm / about.

Concerning assembly, dismantling and an arrangement see the head "The vacuum amplifier of brakes".

1. Remove the stoplight switch.

Fig. 12.8. Fastening of a pedal of a brake: 1 – nut; 2 – washer; 3 – bracket; 4 – arm; 5 – spring forelock; 6 – pedal axis; 7 – spring of prevention of trembling of a pedal; 8 – brake pedal; 9 – overlays of a pedal of a brake

2. Remove a spring of prevention of trembling of a pedal of 9 (fig. 12.8).

3. Remove a lock plate and a finger from a pusher.

4. Remove the spring forelock 5 of a brake pedal axis.

5. Turn off a nut 1 and remove a washer 2. Take out axis 6 on the left side of a pedal.

6. Remove a pedal of a brake 8 of a bracket 3. Note the provision of a returnable spring of a pedal.

1. Establish an overlay of a pedal on a new pedal of a brake.

2. Establish a pedal of a brake 8. Arrange a returnable spring as it was noted before removal.

3. Establish an axis of a pedal 6. Insert an axis on the left side of a pedal. Before installation grease an axis.

4. Establish a washer 2 and screw a nut 1 on an axis of a pedal 6 and tighten the moment 40 N • m.

5. Establish a pusher, a finger and a lock plate.

6. Insert the forelock 5 into an axis of a pedal 6.

7. Install the stoplight switch.

Hollow perepuskny brake support bolt........ 40 N • m

Bolt of fastening of an arm of a support........ 8 N • m

Connection of the brake pipeline........ 11 N • m

Bolt of fastening of the lever of the parking brake........ 25 N • m

Bolts of fastening of sitting of the driver......... 20 N • m

Nut of fastening of a pedal of a brake......... 18 N • m