The main signs of timing chain wear. The main signs of timing chain wear Remove the ZAZ brake drum

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Tavria Nova / Slavuta. Signs of Timing Chain Wear

The main signs of timing chain wear

Rough and uneven work on Idling(the result of changing the valve timing);

Chirping and rustling - especially at idle, when the oil pressure is very low;

Maximum tensioner output (visible after removing the cover);

Sprocket teeth wear (visible after removing the cover);

Corresponding parameters taken from the phase sensor (using a diagnostic tester).

Malfunction symptoms - crackling, clatter, rattling when starting a cold engine, the Chek Engine caught fire or the engine simply does not start.

Premature chain wear due to manufacturing defects. A stretched chain can jump several links. Hence the drop in power, acceleration dynamics, increased fuel consumption, increased engine noise, etc.
Malfunction of the intake camshaft position regulator. It should be replaced with a new optimized version.
Stuck tensioner. The chain tensioner hangs in one position, as a result, the chain does not acquire normal tension.
Thermal protection for the oil pipeline. When replacing a stretched chain, it is necessary to replace the heat shield wrapped along the oil line to the turbine.

If you notice any of these symptoms, you should not delay a trip to a car service, as an open timing chain in some cases can lead to an overhaul of the engine.

How often should the timing chain be changed?
It all depends on the specific engine model. Each engine model has its own standards for replacing the timing chain. On average, the timing chain needs to be changed every 100 thousand km., But this is a very average value, for some models it may be less, while for others it can be much more. Most modern cars, when the timing chain approaches a condition requiring its replacement, give a check engine error, so you will know exactly when it is time to change the timing chain.

Tips for operating and replacing the timing drive

In most new vehicles, the life of the chain is less than the life of the engine;

Pay attention to unusual noises, especially after starting;

Avoid extending oil changes - the more often the better;

Normal oil pressure ensures the operation of the chain tensioner;

If you change the chain, be sure to replace the gears (sprockets) and guides - they also wear out;

When replacing, use original components or high-quality substitutes.

Removing the brake drum front and rear wheels. To remove the front wheel brake drum (made together with the hub), it is necessary to remove the wheel, then, unscrewing the three bolts, remove the decorative wheel cap and remove the hub cap using a screwdriver and hammer. After that, unpin and unscrew the hub fastening nut and, by slightly rocking the hub in a plane perpendicular to the axis, remove the brake drum.

With a significant development of the drum and the formation of a ledge, it may be difficult to remove the drum from the blocks. To remove such drums, they should be extended as far as possible in the axial direction, and then both pads should be upset by hammer blows on the outer diameter of the drum through a wooden spacer. The front drum should be struck in a vertical plane, and the rear drum should be struck in a horizontal plane.

To remove the rear wheel brake drum, you need to remove the decorative wheel cap, then, after unscrewing the six bolts securing the drum to the hub, remove the drum from the shoes. If it is difficult to remove, lightly tap the drum flange with a hammer and remove it from the shoes in the same way as the drum front brake.

^ Removing brake pads. With the help of special pliers or a pointed rod with a diameter of 4 mm, both coupling springs of the shoes are removed, then, lifting the end of the clamping spring, the shoe is removed.

Rice. 134. Fastening the friction linings of the brake with rivets: o-brake block assembly; b-friction lining in the development [dimensions 2.5 mm and (99.8 ± 0.1) mm are indicated after grinding]
When removing the rear brake pads, additional operations should be performed: unpin and remove the expansion lever and spacer bar. Removed brake pads are cleaned of dust and dirt. Worn friction linings are replaced with new ones.

Installation of pads on the brake shield is performed in the reverse order.

^ Replacement of friction linings of brake pads. In the absence of new pads with overlays, you can rivet or glue new pads on the old pads.

P
Before riveting new pads, it is necessary to remove the old pads from the pads by heating the pads to a temperature of 300 ... 350 ° C or cut them down with a chisel and clean them with a file. Eight holes with a diameter of 4.4 mm are drilled on the glued surface of the pads, evenly distributing them over the entire area (Fig. 134). When drilling holes in the overlays, the block should be used as a conductor. After drilling, the holes are countersunk from the side of the outer surface (Fig. 135). Rivets are made of hollow brass rod. Instead of brass, you can use aluminum or copper rivets of the same shape, but with a solid core. A mandrel is used to rivet the rivets (Fig. 136).
"Fig. 135. Dimensions of the rivet and holes for it in the friction lining: a- holes in the lining; b - rivet
Glued linings can be reliably operated up to wear of 80...90% of their initial thickness. However, the gluing process itself can only be performed with special equipment. VS10-T glue is used for gluing the overlays.

Before gluing the pad, the surface of the pad is cleaned with a coarse abrasive wheel to obtain a degreased, rough surface free of scale. The pads are degreased by wiping with a solvent. Then the glued surfaces of the pads and linings are smeared with glue three times, each time allowing to dry until it is poured. Next, pads are glued onto the pads and they are strongly pressed using a device consisting of a tape clamp and an expanding screw. In this form, the pads are placed in an oven, where they are kept at a temperature of 180 ... 200 ° C for an hour.

Glued linings withstand 2-3 times more shear force than riveted ones.

^ Disassembly and assembly of the main brake cylinder. When disassembling the master brake cylinder, you must:

Clean dust and dirt from one of the front and rear brake, remove the rubber protective cap and put a hose for bleeding the hydraulic drive on the head of the front brake valve, lower the free end of the hose into a glass vessel and, having removed the plugs from the necks of the nutrient tanks, pump out the brake fluid. Do the same with the rear brake;

disconnect from brake master cylinder 12 (see Fig. 130) pipelines leading to the brakes and to the master cylinder reservoir;

Unpin the pin 7 of the brake pedal 1, disconnect the pusher fork from the pedal and, unscrewing the two bolts 13 fastening the brake master cylinder to the bracket, remove the brake master cylinder from the socket;

fix the master cylinder in a vise or fixture, remove the protective cap from the cylinder ^ 10 (see Fig. 131) by unscrewing the locking bolts 18 and cork 16, and then remove all parts following the sequence shown in fig. 131.

Rice. 136. Mandrel for riveting the rivets of the lining to brake shoe(surface roughness of the working profile should not exceed 1.25 µm)
After disassembling the cylinder, all parts and the body should be thoroughly washed with alcohol or fresh brake fluid, carefully inspected and made sure that the cylinder mirror and the working surface of the pistons are perfectly clean, that there is no rust, scratches and other irregularities or an increased gap between the pistons and the cylinder.

If damage is found on the cylinder mirror, it is necessary to eliminate them by lapping so that there is no leakage of fluid and premature wear of the piston cuffs. In case of damage that causes a significant change in the inner diameter of the cylinder, it is necessary to replace the cylinder body with a new one. It is recommended to replace the seals with new ones every time the cylinder is dismantled, even if they still appear to be in good condition.

It is also necessary to check the condition of the protective cap of the cylinder and, if it is damaged, replace it with a new one. Check if the piston springs have lost elasticity.

Before assembly, all parts of the brake cylinder and the inner cavity of the cylinder are lubricated with castor oil or fresh brake fluid. The assembly of the cylinder is carried out in the reverse order of disassembly, avoiding the ingress of dust, fibers from the fabric, etc.

After installing the master brake cylinder on the car and connecting the hydraulic drive pipelines, the system is filled with liquid and air is removed from it.

Disassembly and assembly of wheel brake cylinders. For with n I - t and I of the wheel brake cylinders of the front wheels must be unscrewed (Fig. 137) connecting nuts of the pipelines 9 and 8, coming from the master brake cylinder 6 to flexible hoses 7 and 7, then remove brackets /7 fastening the flexible hoses to the brackets and unscrew the flexible hoses from the brake cylinders. Turn away from the shield 3 (see fig. 128) brake connecting pipe 6, then unscrew two bolts 7 and remove the upper and lower brake cylinders from the shield. Do the same on the second shield of the front brake.

To remove the brake cylinders of the rear wheels, it is necessary to unscrew the connecting nuts of the pipelines 15 and 10 (see Fig. 137) from the brake cylinders and, having unscrewed two bolts, remove the cylinders from the shields.

Disassembly of the brake cylinder should be performed in the following sequence: remove the protective covers 7 (Fig. 138), unscrew the pistons 6 thrust ring cylinder 4, With use a copper or wooden drift to knock out (only if absolutely necessary) the thrust rings 4 rear brake cylinder. The parts of the disassembled brake cylinder are thoroughly washed, inspected and determined for their suitability for further work.

Assembly of wheel brake cylinders is carried out in the reverse order, taking into account the following instructions.

Pistons are installed only on the side of the cylinder from which they were turned out. Before assembly, all parts are thoroughly washed in alcohol or fresh brake fluid and blown compressed air. It is not recommended to wipe parts with rags or ends to avoid contact with sealing surfaces fibers.. Cuffs 4 (Fig. 139), pistons 5 and the inner surface of the cylinder 3 before assembly, lubricate with castor oil or fresh brake fluid.

When installing the pistons in the cylinder, they must be screwed into the rings completely, and then unscrewed by half a turn, otherwise the pistons will not move in the thread and the drums will jam. In this case, the slot on the piston support rod must be parallel to the brake shield.

When assembling the cylinder, it is necessary to set the piston with rings to its original position, for which, with light blows on the support rod, set the piston so that the support surface of the rod sinks from the edge of the cylinder by 7 mm.

Disassembly and assembly of the front brake wheel cylinder is carried out in the same way as for the rear brake. All connections must be tightly tightened to ensure tightness.

After installing and fixing the cylinders on the brake shield, assembling the shoes with springs and installing the brake drum in place, air must be removed from the hydraulic drive system.

Rice. 137. Pipelines hydraulic drive brakes. 1.7 - front brake hoses; 2 - tee; 3 - washer; 4 - nut; 5, 8, 9, 10, 12, 15, 16 - pipelines; 6 - main cylinder; 11 - flexible hose rear wheel drive brakes; 13 - tee; 14 - flexible hose of the rear left brake; 17 - bracket.

Rice. 138. Details of the wheel cylinders of the front and rear brakes: 1 - the upper wheel cylinder of the front brake; 2 - washer; 3 - clutch; 4 - split spring ring; 5 - cuff; 6 - piston; 7 - protective cover: 8 - valve; 9 - rear brake wheel cylinder

Rice. 139. Wheel brake cylinder rear brake: / - support rod; ^ 2 - protective cover; 3- cylinder; 4- cuff; 5- piston: 6- snap ring
Dismantling of pipelines of a drive of brakes. Unscrew (see Fig. 137) the connecting nuts of pipelines 5, 8, 9, 10, 12, 15, 16 remove the brackets 17 for fastening the hoses 1, 7, 11 and 14 and tee 2 and 13, remove tubes and hoses. Damaged pipelines or nuts, as well as hoses, are replaced with new ones.

Before installation, the pipelines are thoroughly washed in denatured alcohol, alcohol or gasoline and blown with compressed air. After installing a new front brake hose, make sure that at maximum front wheel steering angles, the hose does not touch the wheel tire or the suspension arms. Front wheel hoses are interchangeable, rear wheel hoses are non-interchangeable.

^ filling brake system fluid and removing air from it. To refuel the hydraulic brake drive, Neva brake fluid (TU 6-01-1163-78) or BSK (TU 6-10-1533-75) is used. It is strictly forbidden to fill the system (or add the smallest amount) mineral oils, gasoline, kerosene or mixtures thereof. Do not mix brake fluids before refueling. different brands, as well as adding a liquid of a different composition to the one that is already in the hydraulic drive system. The use of glycerin-based brake fluid is not permitted.

Fill a clean glass transparent vessel with a capacity of approximately 0.5 liters from 1/3 to 1/2 of the height;

remove the plug from the neck of the nutrient tank of the main brake cylinder and fill with liquid to a normal level;

Clean the valves for venting air from the wheel cylinders from dust and dirt and remove the rubber protective caps. Put the hose for pumping the hydraulic drive on the head of the air release valve of any one wheel, and lower the free end of the hose into a glass vessel. In doing so, it must be borne in mind - do not depress the brake pedal when removed. at least one brake drum, as the pressure in the system will squeeze the pistons out of the wheel cylinder and brake fluid flow out;

Press the brake pedal sharply 3...5 times with an interval between pressing 2...3 s and, holding the pedal depressed, unscrew the valve by 1/2...3/4 turn, displacing the liquid in the system by pressing the pedal together with air until the pedal stops completely. Without releasing the pedal, close the valve. Repeat these steps for each wheel. When performing these operations, a normal liquid level must be maintained in the nutrient tank.

You can also remove air from the system by supplying air under pressure (for each pair of brakes) no more than 2 kgf / cm 2 to the tank with the bleeding valve open, without touching the brake pedal.

With normal clearances between the brake pads and drums and the absence of air in the system, the brake pedal, when pressed with a foot, should not move more than 90 ... 95 mm of its travel. In this case, the leg should feel strong resistance (feeling of a “hard” pedal). If the pedal travels further, but the pedal is "stiff", then this indicates increased clearance between the pads and the brake drums. In this case, it is necessary to make five or six sharp braking when the car is moving forward at a speed of 30 km / h and several sharp braking when reversing.

^ Drive disassembly and assembly parking brake. To remove the parking brake drive from the car, you must:

Unpin and remove from the spreader lever pin ^ 8 (see fig. 133) cable end 4, bend the bracket II fastening the shell to the lever rear suspension and remove the cable from the stop bracket. Perform the same operations on the second rear suspension arm;

remove five screws ^ 12 cover fasteners 3 floor tunnel and remove the cable from the openings of the cover;

Loosen four screws 5 fastening the parking brake lever to the tunnel and pull it out of the tunnel assembly with the cable.

To disassemble the parking brake lever, unpin and remove the pins of the roller and sector, remove the locking

ring and knock out the axis of the lever, then unscrew the button and remove the spring and button rod from the lever.

Brake drive parts must be thoroughly rinsed in gasoline and inspected. The main faults of the drive may be excessive stretching of the cable, which must be replaced (provided that all three adjustments for cable stretching have been used), or wear of the pawl tooth. A worn dog is replaced with a new one.

Assembly the parking brake actuator and its installation on the car is carried out in the reverse order. When assembling, all rubbing surfaces of the drive (axle shaft and cable) should be lubricated with graphite grease.

^ Parking brake actuator adjustment. When properly adjusted, the parking brake should securely hold the vehicle on a slope. The need to adjust the parking brake drive in operation is caused by two reasons: wear of the friction linings of the brake of the rear wheels and stretching and loosening of the drive cable.

To adjust, place the car on stands so that the rear wheels rotate freely, make sure by the amount of free play of the brake pedal that the gaps between the shoes and the brake drums of the service brake drive are correct. The parking brake lever must be in the lowest position.

There are three ways to adjust the parking brake actuator (see Fig. 133):

Changing the rope tension by moving the bracket 6 lever forward. To do this, loosen the four bolts securing the bracket to the tunnel and slide the bracket forward along the oval holes. Tighten the two bolts and check the movement of the lever. The stroke of the lever until the wheels are completely braked should not exceed four or five clicks of the ratchet. After adjustment, tighten the bracket mounting bolts;

when using the entire length of the oval holes, it is possible to additionally tighten the cable by moving the balancing roller to the next hole A in the lever, after which the operations indicated in the previous paragraph should be repeated;

regardless of the cable extension, the travel of the spreading lever on the brake shield increases due to the wear of the brake pad linings and their automatic shift towards the drum.

If the brake linings are worn by 50...60% of their thickness and it is impossible to ensure the effectiveness of the brake only due to the above adjustments, the spacer bars should be rearranged 9 both brakes on larger size. If, after rearranging the slats, braking occurs when the lever is moved two or three clicks, it is necessary to loosen the cable tension using the lever bracket or by moving the leveling roller.

Periodic maintenance of the ZAZ brake system is carried out at the following stages:

After 20 thousand kilometers, the brake drums are dismantled, the brake is cleaned of dirt, the friction linings are checked, and the brake pads are updated (as needed).
After a run of 60 thousand kilometers, the brake cylinders are disassembled, washed and examined for worn and faulty parts. After replacing the unusable parts with new ones, the system is purged and the fluid is replaced.

Friction linings on brake pads have a relatively short service life - about 30 thousand kilometers. Lining wear is largely dependent on driving style and road conditions. It is advisable to replace the drums when overhaul auto. The absence of dirt in the hydraulic brake drive, as well as the use of high-quality fluid, guarantees long-term and reliable performance systems.

Removing the ZAZ brake drum

We dismantle front wheel, unscrewing 3 bolts, remove the cap, unfasten the hub cap with a hammer and screwdriver. Then we take out the cotter pin and unscrew the nut of the hub connection, gently shake the hub perpendicular to the axis, pull out the brake drum.

drums after long-term operation may be with a ledge, in which release from the blocks is difficult. Use the following method: push the drum as far as possible along the axis, tap with a hammer on the outer diameter of the drum (putting wood linings) - this will settle the pads. To dismantle the front drums, the impulse should be transmitted vertically, for the rear - horizontally.

On the rear wheels, the ZAZ brake drum is removed as follows: remove the cap, unscrew the 6 fastening bolts between the hub and the drum, remove the drum from the shoes. If you cannot remove it, tap the drum flange with a hammer.

Since the friction linings of the pads on ZAZ wear out much earlier than the brake drums, you should understand the principles for replacing them. Often new pads are glued onto old pads. To do this, heat the old pads to 300 ° C and remove them, or cut them off with a chisel and sand them with a file. The surface of the pads intended for gluing needs 8 holes of 4.4 mm; these holes should be evenly distributed over the area. Using the block as a conductor, we drill holes in the overlays themselves. We process the holes with a countersink from the outside. Using a mandrel, we rivet rivets made of brass, aluminum or copper. The overlays work until they are erased by 90% of the initial thickness.

When servicing the brake system, it is necessary to know and use materials correctly. On the overlays, BC 10 T glue is used, it allows you to withstand three times the increased shear force than in the case of riveting.

Timely diagnosis and Maintenance brake system will eliminate performance problems.

The brake system of the car ZAZ-965a "Zaporozhets"

On a ZAZ-965A "Zaporozhets" car, the brake system consists of wheel shoe brakes with a hydraulic drive from a foot pedal. The rear wheel brakes have, in addition, a manual mechanical drive from a lever located with right side driver's seat.

Wheel brakes are shoe, self-adjusting. All brakes have one working cylinder. The rod of the main brake cylinder is connected to the brake pedal. The brake pedal with its hub, which has a plastic sleeve, is mounted on the pedal bracket and is equipped with a release spring. The main brake cylinder is fixed on the front shield of the body and is connected by a tube to a reservoir located in the trunk of the body. From the master cylinder, pipelines are connected to the brake cylinders of the wheel brakes.

The gap between the shoes and the brake drum is adjusted by eccentrics installed in the brake shields.

The lever of the manual mechanical drive of the rear brakes is equipped with an equalizer roller, through which a cable is thrown, passing in the guide shells. The ends of the cable are connected to expansion levers that act on the rear brake pads.

The manual drive of the rear brakes is adjusted using the threaded ends of the cables, by shifting the lever bracket and rearranging the roller in the cheeks of the lever.

On a ZAZ-965 Zaporozhets car, the brake system has the same device.

Disassembly and assembly of the steering gear joints. At disassembly the steering drive must be unpinned and unscrew the nut of the ball pin (Fig. 126).

Rice. 126. Steering gear: 1 - transverse link locknut; 2 - locknut of the transverse link (left thread); 3 - transverse thrust; 4 - pendulum lever; 5 - nut; 6 - protective cover; 7 - thrust washer; 8 - wire; 9 - tip; 10 - sealant; 11 - plug; 12 - retaining ring; 13 - spring; 14 - pressure insert; 15 - insert; 16 - finger; 17 - rotary fist; 18 - steering rod left; 19 - bipod of the steering mechanism; 20 - hole for turning the rod when adjusting the toe-in; 21 - turn limiters

Loosen the ball stud with a puller or apply a few sharp hammer blows to the sides of the pivot arm head. Then, if necessary, with light blows of a hammer on the end of the finger through a copper or aluminum rod, knock out the finger from the conical hole. Tie rods can be removed together with the pendulum arm and steering arm. To do this, it is necessary to remove the ball pins from the heads of the rotary levers (as described above), remove the bracket with the pendulum lever and remove the steering arm.

Then unfold the wire 8 and remove the protective cover with a thrust washer from the ball pin 7. Remove the bitumen mastic from the plug with a screwdriver and, squeezing the antennae of the lock 12, take out the plug II, spring 13, pressure pad 14, ball pin 16 with support pads 15.

The assembly of the steering gear is carried out in the reverse order. Before assembly, rinse and check the condition of the parts.

If the finger head does not have deep traces of corrosion and wear, it can be used for further operation. Slight blackness and rust can be removed by cleaning the head with fine glass sandpaper and oil.

When installing new inserts 15 on fingers 16 you need to check the end gap between them. The gap between the liners should be 1.5...2.0 mm. When assembling, lubricate the liners with gear grease, and also check for the presence of a sealing washer 10 and cleanliness of the groove for the retaining ring 12. If the seal 10 damaged, it is replaced with a new one. If factory-made sealing washers are not available, they can be made from 3.5 mm thick oil-resistant rubber sheet.

Attention should be paid to the condition of the rubber protective cover, the further operation of the hinge depends on the integrity and correct installation of which.

Disassembly and assembly of the pendulum lever. Disassembly it is recommended to proceed in the following order:

press a pin into the hole in the pendulum lever with the axis and punch the hole from the side of the press-in at three points. When pressing the pin, it is necessary to install the pendulum lever so that there is a gap of at least 2 mm between the upper plane of the lever and the bracket (see Fig. 127).

BRAKE SYSTEM

DESIGN FEATURES OF THE BRAKING SYSTEM

The car is equipped with drum-type brake mechanisms with floating (self-aligning) shoes and a device for automatically maintaining a constant gap between the drums and shoes. To control the brake mechanisms, the car is equipped with two independent drives: hydraulic from a foot pedal, acting on all wheels, and mechanical from a manual handle, acting only on the rear wheels.

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The hydraulic brake drive consists of two independent systems for braking the front and rear wheels. The master cylinder has two independent cavities with two pistons and one tank with two hoses to supply liquid to each cavity separately. Two independent systems are introduced for safety. If one pipeline is damaged, one braking system will not work, and the second will work.

The brake mechanisms of the front wheels (Fig. 128) are mounted on stamped steel shields, which are attached to knuckles three bolts. Each brake has two working wheel cylinders with an inner diameter of the upper - 22 and lower - 19 mm, each of which acts on one of the two pads.

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Rice. 130. Details of the hydraulic drive of the brakes: 1 - pedal; 2 - sealant; 3 - bracket; 4, 13, 15 - bolts; 5 - spacer sleeve; 6 - sleeve; 7 - finger; 8 - fork; 9 - tank; 10 - tank fastening nut; 11 - flexible hose; 12 - master cylinder assembly; 14 - spring; 16 - pusher.

The wheel brake cylinder consists of thrust split rings, which are pressed into the cylinders with a force of at least 35 kgf. The slot of the rings is installed parallel to the brake shield. The rings have a rectangular thread inside, through which pistons with sealing collars are screwed into them. The thread root width of the ring is larger than the thread on the piston. The piston can move freely relative to the ring by 2 mm . A steel support rod is pressed into the piston, into the groove of which the end of the rib of the pad (the toe of the pad) enters. The rubber protective cover protects the inner surface of the cylinder from dust, water and dirt.

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Rice. 132. Hydraulic brake drive: 1 - brake light switch; 2 - screw; 3 - tip; 4 - screw; 5 - pusher; 6 - master cylinder; 7 - spring; 8 - pedal

Cuffs have a toroidal cross-section, outside diameter which in the free state slightly exceeds the inner diameter of the cylinder. If the rings are not subjected to brake fluid pressure, then only the middle outer belt of the rings is in contact with the cylinder surface, and the edges do not touch.

Under the influence of brake fluid pressure, radial and axial pressure causes the rubber rings to expand, thus creating a seal with the cylinder mirror. The side of the cuff facing the piston is pressed against the cylinder surface, and the opposite side, washed by the liquid under pressure, retains its rounded shape and remains separated from the cylinder surface even when moving.

The contact area between the seals and the cylinder face is reduced to a minimum, and the rounded shape on the cylinder face side provides quite satisfactory sliding surface lubrication with particularly low frictional resistance. The cavities formed between the parts of the master cylinder, at rest, have a volume that fully compensates for the expansion of the brake fluid.

The rear brake actuator piston is actuated by brake fluid pressure, and the front brake actuator piston is actuated by the pusher when the brake pedal is depressed.

The brake master cylinder has an inner diameter of 19mm. Between the pusher and the piston there must be a gap of 0.3 ... 0.9 mm (Fig. 132), which is provided by changing the position of the switch 1 brake signal and adjustable pusher and threaded tip design). In this case, the pedal free play is 1.5 ... 5 mm. The position of the pedal is adjusted as follows:

by changing the position of the switch, the pedal stroke is set to 160 ... 165 mm, while the pusher stroke 5 should be 30...31 mm;

by changing the length of the pusher, a gap between the pusher and the piston is set to 0.3 ... 0.9 mm. Control is carried out by measuring the gap between the pedal stop 8 and plastic tip 3 brake light switch.

As the pads and drums wear, the stroke of the pistons of the wheel cylinders increases and the stroke of the brake pedal increases accordingly. To restore the normal travel of the brake pedal, on a flat dry highway, carry out five or six sharp braking, moving at a speed of 30 km / h forward, as well as several sharp braking, moving in reverse.

Parking brake(Fig. 133) acts on the brake pads of the rear wheels by means of a lever and rods. The lever oscillates on an axle in a bracket attached to the floor tunnel with four bolts. The bracket has oval holes that serve to move the bracket when adjusting the brake (cable tension). In the holder of the lever there is an additional hole for rearranging the roller with a significant stretch of the cable.

The spacer bar has an additional slot with a smaller recess. When friction linings are worn by 50 ... 60% of their thickness, it is recommended to rearrange the spacer bars to a larger size.

Flange" href="/text/category/flantci/" rel="bookmark">drum flange and remove it from the shoes in the same way as the front brake drum.

Removing brake pads. With the help of special pliers or a pointed rod with a diameter of 4 mm, both coupling springs of the shoes are removed, then, lifting the end of the clamping spring, the shoe is removed.

Rice. 134. Fastening the friction linings of the brake with rivets: o-brake block assembly; b-friction lining in the development [dimensions 2.5 mm and (99.8 ± 0.1) mm are indicated after grinding]

When removing the rear brake pads, additional operations should be performed: unpin and remove the expansion lever and spacer bar. Removed brake pads are cleaned of dust and dirt. Worn friction linings are replaced with new ones.

Installation of pads on the brake shield is performed in the reverse order.

Replacement of friction linings of brake pads. In the absence of new pads with overlays, you can rivet or glue new pads on the old pads.

Before riveting new pads, it is necessary to remove the old pads from the pads by heating the pads to a temperature of 300 ... 350 ° C or cut them with a chisel and clean them with a file. Eight holes with a diameter of 4.4 mm are drilled on the glued surface of the pads, evenly distributing them over the entire area (Fig. 134). When drilling holes in the overlays, the block should be used as a conductor. After drilling, the holes are countersunk from the side of the outer surface (Fig. 135). Rivets are made of hollow brass rod. Instead of brass, you can use aluminum or copper rivets of the same shape, but with a solid core. A mandrel is used to rivet the rivets (Fig. 136).

"Fig. 135. Dimensions of the rivet and holes for it in the friction lining: a - holes in the lining; b - rivet

Glued linings can be reliably operated up to wear of 80...90% of their initial thickness. However, the gluing process itself can only be performed with special equipment. VS10-T glue is used for gluing the overlays.

Glued linings withstand 2-3 times more shear force than riveted ones.

Dismantling and assembly of the main brake cylinder. When disassembling the master brake cylinder, you must:

clean one of the front and rear brake air release valves from dust and dirt, remove the rubber protective cap and put a hose for pumping the hydraulic drive on the head of the front brake valve, lower the free end of the hose into a glass vessel and, having removed the plugs from the necks of the nutrient tanks, pump out the brake fluid . Do the same with the rear brake;

disconnect from brake master cylinder 12 (see Fig. 130) pipelines leading to the brakes and to the master cylinder reservoir;

unpin the pin 7 of the brake pedal 1, disconnect the pusher fork from the pedal and, unscrewing the two bolts 13 fastening the brake master cylinder to the bracket, remove the brake master cylinder from the socket;

fix the master cylinder in a vise or fixture, remove the protective cap from the cylinder 10 (see Fig. 131) by unscrewing the locking bolts 18 and cork 16, and then remove all parts following the sequence shown in fig. 131.

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Rice. 136. Mandrel for riveting the lining rivets to the brake shoe (surface roughness of the working profile should not exceed 1.25 microns)

After disassembling the cylinder, all parts and the body should be thoroughly washed with alcohol or fresh brake fluid, carefully inspected and made sure that the cylinder mirror and the working surface of the pistons are perfectly clean, that there is no rust, scratches and other irregularities or an increased gap between the pistons and the cylinder.

It is also necessary to check the condition of the protective cap of the cylinder and, if it is damaged, replace it with a new one. Check if the piston springs have lost elasticity.

After installing the master brake cylinder on the car and connecting the hydraulic drive pipelines, the system is filled with liquid and air is removed from it.

Assembly of wheel brake cylinders is carried out in the reverse order, taking into account the following instructions.

Pistons are installed only on the side of the cylinder from which they were turned out. Before assembly, all parts are thoroughly washed in alcohol or fresh brake fluid and blown with compressed air. It is not recommended to wipe the parts with rags or ends to avoid getting fibers on the sealing surfaces. 4 (Fig. 139), pistons 5 and the inner surface of the cylinder 3 before assembly, lubricate with castor oil or fresh brake fluid.

Disassembly and assembly of the front brake wheel cylinder is carried out in the same way as for the rear brake. All connections must be tightly tightened to ensure tightness.

After installing and fixing the cylinders on the brake shield, assembling the shoes with springs and installing the brake drum in place, air must be removed from the hydraulic drive system.

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Rice. 139. Wheel brake cylinder rear brake: / - support rod; 2 - protective cover; 3- cylinder; 4- cuff; 5- piston: 6- snap ring

Dismantling of pipelines of a drive of brakes. Unscrew (see Fig. 137) the connecting nuts of pipelines 5, 8, 9, 10, 12, 15, 16 remove the brackets 17 for fastening the hoses 1, 7, 11 and 14 and tee 2 and 13, remove tubes and hoses. Damaged pipelines or nuts, as well as hoses, are replaced with new ones.

Filling the brake system with fluid and removing air from it. To refuel the hydraulic brake drive, Neva brake fluid (TU 8) or BSK (TU 5) is used. It is strictly forbidden to fill the system (or add the smallest amount) with mineral oils, gasoline, kerosene or mixtures thereof. It is not allowed to mix brake fluids of different brands before refueling, as well as add a fluid of a different composition to the one that is already in the hydraulic drive system. The use of glycerin-based brake fluid is not permitted.

fill a clean glass transparent vessel with a capacity of approximately 0.5 liters from 1/3 to 1/2 of the height;

remove the plug from the neck of the nutrient tank of the main brake cylinder and fill with liquid to a normal level;

clean the valves for air release from the wheel cylinders from dust and dirt and remove the rubber protective caps. Put the hose for pumping the hydraulic drive on the head of the air release valve of any one wheel, and lower the free end of the hose into a glass vessel. In doing so, it must be borne in mind - do not depress the brake pedal when removed. at least one brake drum, as the pressure in the system will squeeze the pistons out of the wheel cylinder and the brake fluid will flow out;