Why do the brakes work spontaneously when the engine is running. Typical malfunctions of the hydraulic brake drive

Brake system malfunctions

Brake malfunctions arising during the operation of the car include: insufficient braking efficiency, non-simultaneity of their action, poor release or jamming of the brake mechanisms, increased free or working pedal travel, incomplete wheel release, strong heating of discs and brake drums, an increase in the force applied to brake pedal, skidding or drifting of the car during braking, creak or vibration of the wheel brakes, spontaneous braking when the engine is running.

Insufficient braking efficiency excludes the possibility of a timely stopping of the car under normal driving conditions, and in difficult situations, to road accidents.

The non-simultaneous action of the brakes does not allow the car to be stopped in a timely and correct manner, and leads to a skid when braking. Poor wheel release causes overheating of the brakes, rapid wear of the brake linings and, as a result, seizure or weak brake action.

The reason for the weak action of the brakes may be the lack of tightness of the pneumatic drive system, violation of the adjustment of the drive and brake mechanisms, wear or oiling of the brake pad linings, insufficient air pressure in the pneumatic brake system.

Non-simultaneous action of the wheel brakes can be caused by: violation of the adjustments of the drive or brake mechanisms, jamming of the rods, as well as clogging of hoses and pipelines.

Jamming of brakes can be due to: breakage of tension springs or breakage of brake pad linings, jamming of camshafts and drive rollers, malfunction of brake valves.

Conventional abbreviations are adopted in the text:KM - driver's crane No. 394 (395);

Kwt - auxiliary brake valve No. 254;TM - brake line;PM - feed line;Shopping center - brake cylinder;LPC - low pressure cylinder;CVP - high pressure cylinder;GR - main tank;ZR - spare tank;SD - surge tank;BP - air diffuser;ZK - spool chamber of the air distributor;MK - main air distributor chamber;RK - working chamber of the air distributor;UP - equalizing piston;RD - pressure regulator;THEN - Maintenance;TR - Maintenance;EVR - electric air distributor;EPT - electro-pneumatic brake;DNTs - train dispatcher

Possible malfunctions of the crane driver No. 394 (395)

The increase in pressure in the TM at the positionIIhandles of the crane operator. Possible reasons):

increased leaks in the surge tank or its connections;

violation of the density of the gearbox diaphragm at the place of its attachment or a crack in the diaphragm;

missing gear valve due to its unsatisfactory lapping or dirt particles getting under the valve;

skipping the spool due to a violation of lapping to the mirror or contamination of the lubricant;

clogging of the 0.45 mm hole in the stabilizer with the slightest miss of the reducer valve;

clogging of the 1.6 mm hole in the body of the middle part of the valve. With this malfunction, overpressure will be observed on the TM manometer. In turn, the UR manometer will not overestimate;

inaccurate setting of the KM handle to position II due to wear of the gradation sector on the valve body, loosening of the valve handle on the rod, subsidence of the spring that fixes the handle cam, working out of the handle over the square of the rod, driver errors.

Running a train with a recharged brake line is unacceptable. In a passenger train, simultaneously with the recharging of the TM, the recharging of the air defense cars takes place. The disadvantage of air distributor No. 292 is that the air pressure in the shopping center during braking depends on the pressure in the airlock. If we allow an increase in pressure in TM and ZR of more than 5.5 kgf / cm 2 and continue running the train, then in the case of service or emergency braking, significant pressure is created in the shopping center, which leads to jamming of the wheelsets of the entire train. The result is the formation of sliders, an increase in braking distance, and a threat to traffic safety.

In a freight train, when the TM is recharged, the ZR is recharged, as well as the ZK and RK in the air distributor. The increased pressure in the ZR does not lead to increased pressure in the shopping center during braking, since the cargo air distributors have a mode switch for loaded, medium and empty modes, which will stop filling the shopping center depending on the set mode.

But the increased pressure in the RK makes it difficult to release the brakes after service braking, as a result of which some air distributors, especially in the tail section of the train, do not go into the release position. To release the brakes, it is necessary to further increase the already high pressure in the TM, and this is unacceptable.

If, when driving a train, the pressure in the brake line turns out to be more than 7.5 kgf / cm 2, then after the compressors are turned off, the pressure in the main tanks will begin to decrease by the regulator. When the pressure in the GR becomes less than the air pressure in the TM, self-braking of the train may occur at position II of the KM handle.

While driving the train, the locomotive crew must constantly monitor the air pressure in the GR, UR and TM. In case of timely detection of the incipient overpressure in the TM (in a passenger train no more than 5.5 kgf / cm 2, in a freight train - no more than 6.5 kgf / cm 2), the driver must move the driver's crane handle to position IV, observing the readings of the TM manometers and ur.

If in position IV of the KM handles:

overstatement pressure air pre stolen , then the malfunction is in the reducer valve. You can continue driving the train in position IV of the KM handle and try to lightly tap the plug of the reducer valve to remove a particle of dirt that has gotten in and press the valve to the seat. In addition, it is possible to tighten the stabilizer spring with the adjusting screw, thereby increasing the amount of air released from the UR into the atmosphere through the stabilizer, and then move the KM knob to position II. If it is not possible to eliminate the increase in air pressure, then it is necessary to return the KM handle to position IV and drive the train to the first stop, maintaining the air pressure in the TM, periodically moving the valve handle from position IV to II, and then to position IV. In the parking lot, secure the locomotive in the sixth position of the KVT, turn off the combined crane, discharge the UR with position V or VI of the KM handle and replace the gearbox from the inoperative cabin. Then it is necessary to move the KM handle to position I, open the combined valve, charge the TM, at position II of the KM handle, adjust the stabilizer (if the spring force has changed), perform a short test of the brakes and continue driving the train;

overstatement pressure in TM and UR continue pressed - the spool allows air to pass through. You can tighten the stabilizer spring with the adjusting screw and return the KM knob to position II. If it is not possible to eliminate the increase in pressure, then, if possible, at the station or on a favorable track profile, it is necessary to stop the train with a stage of service braking. In the parking lot, the KM and KBT handles must be moved to position VI, the brake lock No. 367 must be turned off and the locomotive must be secured with a hand brake. On locomotives without blocking No. 367, turn off the combined crane and the double-draft crane, move the KM and KBT handles to positions VI and secure the locomotive with a hand brake. Then proceed as follows. Replace the upper and middle parts of the crane from the inoperative cabin, turn on the lock of brakes No. 367 (on locomotives without locking, open the combined crane and the double-draft crane), charge the TM, adjust the stabilizer (if the spring force has changed), perform a short test of the brakes, release the manual brake and continue driving the train;

happens decline pressure in UR and TM with triggering brakes trains. The reason is leaks in the UR through its connections or with the driver's crane, or a pressure gauge. If it is not possible to eliminate the malfunction, then in order to release the haul, it is allowed to switch to brake control from the rear cab, having previously tested the brakes;

overstatement pressure in TM due to ma diaphragm reducer or violations density her fastenings v corps - determined by the outlet of compressed air through the atmospheric hole in the adjusting screw of the gearbox at position II of the KM handle. You can stop the air pressure increase by setting the KM knob to position IV, while continuing to drive the train to the station. When the pressure in the TM drops below the charger, the KM handle should be briefly moved to position II, and after the pressure in the TM to the charger is increased, again to position IV. In the parking lot, it is necessary to replace the reducer from the inoperative cabin in the manner described for the case when the overpressure at position IV of the crane handle stops;

overstatement pressure in TM stop it Elk, in SD and at position II , and at polo genii IV pens KM - pressure charger. The reason is the clogging of the 1.6 mm hole. Immediately move the KM handle to the V position and stop the train. If at position V of the KM handle TM does not discharge, then the train must be stopped by emergency braking. At the parking lot, it is necessary to replace the upper and middle parts of the crane from the inoperative cabin, similar to the described case, when the overpressure in the TM and UR continues, to charge the TM, test the brakes and continue driving the train.

Decrease in air pressure in TM at positionIIKM handles. Possible reasons:

error driver ... When the KM handle is displaced by about 8 degrees from position II towards position III, the feeding of the UR from the GR through the spool and the reducer stops. When the KM handle is displaced by 10 - 20 degrees, the UR and UK begin to communicate with the TM through the valve check valve. In operation, there were cases of erroneous incomplete overlap by the operator of the combined crane, as a result of which normal filling of leaks in the TM does not occur;

clogging filter To nutritious valve reducer ... In this case, you can continue driving the train, maintaining the pressure in the UR and TM by briefly moving the KM handle to position I. At the first parking lot, turn off the combined valve, discharge the UR with position V or VI of the KM handle, remove the gearbox and gasket, unscrew the filter and clean it. After that, assemble the crane, charge the UR and TM, test the brakes and continue driving the train. In case of this malfunction, you can replace the filter from the crane of an inoperative cabin.

Slow elimination of supercharged pressure. Reasons: incorrect adjustment of the stabilizer; hole clogging 0.45 mm. The hole must be cleaned with a non-metallic object (for example, a pointed match).

Rapid elimination of overcharge pressure. Reasons: incorrect adjustment of the stabilizer; breakage of the stabilizer diaphragm. Determined by the release of compressed air through the stabilizer adjusting screw. It is necessary to stop the train, if possible, at a station or a favorable track profile and replace the stabilizer from the inoperative cabin at position IV of the KM handle. Another reason is that there are increased air leaks from the UR. In this case, after lowering the pressure to the charging pressure, an increase in the pressure in the TM is possible. This malfunction is detected after moving the KM handle to position IV.

IVafter the performed braking, the pressure in the UR and TM rises. Reasons: skipping of the spool or inlet valve of the KM with an unsatisfactory density of the UE. When these malfunctions occur, the increase in pressure in the TM can lead to the release of the brakes. Therefore, when driving a passenger train, position III of the KM handle can be used as an overlap. When driving a freight train, the minimum braking steps should be avoided and when the pressure rises, use the VA position of the KM handle. If, after braking has been performed, before the inhibiting signal, the pressure in the TM begins to increase, then emergency braking must be applied.

When setting the KM knob to the positionIVafterperformed braking, the pressure in the UR decreases andTM. Reasons: leaks in the UR or through its connections, missing spool or UE seals. These malfunctions cause an increase in the braking effect uncontrollable by the driver. Therefore, when adjusting braking, the minimum set TM discharges should be performed.

After discharging the UR to the required value andsetting the KM handle to the positionIV TM discharge continues for a large amount, and then there is a sharp short-term increase in pressure in TM. Cause: Insensitive balance piston. This malfunction can lead to the release of the brakes of a part of the train, and at the minimum stages of braking with the discharge of the UR by 0.3 kgf / cm 2, the pressure in the TM may not decrease at all.

Driving the train and controlling the brakes with the given KM malfunction is very difficult and dangerous from the point of view of traffic safety. To release the haul after stopping the train, you can switch to brake control from the inoperative cabin. At the station, it is necessary to disassemble the faulty CM, carefully inspect, and also wipe the UE and the piston sleeve, lubricate them, and then assemble the crane and check its operation. The sensitivity of the UE must be monitored during the acceptance of the locomotive.

After reducing the pressure on the UR manometer by the required amount by position V of the KM handle and moving it to position IV, the pressure observed on the UR manometer is briefly overestimated. Reason: the hole in the fitting from the UR to the driver's crane is narrowed. With this malfunction, the TM is discharged to a lesser extent than planned by the driver, which, in turn, reduces the braking effect. In the worst case, a malfunction can lead to a short-term increase in pressure in the TM. In this case, after a stage of braking, it is necessary to briefly hold the KM handle in position III, and then move it to position IV.

Slow rate of discharge of UR and TM at position V of the KM handle. Causes: clogged holes 2.3 or 1.6 mm; omission of the UP seal. These malfunctions can be identified when checking the CM during the acceptance of the locomotive at the depot.

With a short-term setting of the KM knob to the V position, the TM is completely discharged. Reasons: the tube from the UR to the KM is frozen; "the hole in the fitting from the UR is blocked. If it is not possible to find the place of the malfunction and eliminate it, then it is necessary to switch to the brake control from the rear cab.

Interaction of workers of the locomotive and carriage facilities when the brakes are triggered or the locomotive crew applies for insufficient braking pressure (breakage of supply pipes, end valves, disconnection of brake hoses, malfunction of air distributors)

If there was a spontaneous actuation of the automatic brakes, then in this case, an abbreviated testing of the automatic brakes is carried out with a check of the condition of the brake line by the action of the brakes of the two tail cars.
If, when the train is moving, the break signal is triggered and the traction mode is turned off due to self-braking and additional discharge of the line by air distributors, the train speed does not sharply decrease in this case. In this case, the driver is obliged to check the integrity of the brake line by setting the driver's crane handle to position III. After making sure of the integrity of the line by the absence of a rapid continuous decrease in pressure, the driver performs a braking stage and releases the brakes.
If the warning light comes on at a train stop and the traction mode does not turn off, which may indicate overlapping of the end valves in the train or arbitrary discharge of the brake line in the train. In this case, before the train departs, it is necessary to make sure that the signaling device is in good working order by giving a braking stage by reducing the pressure by 0.6-0.7 kgf / cm2 (the lamp goes out) and releasing the brakes. After that, the possibility of turning on the traction mode is automatically restored. In the event of a faulty signaling device, an abbreviated test of the automatic brakes is carried out with a check of the action of the brakes of the two tail carriages.
Reduced testing of the brakes is also carried out after any disconnection of the hoses in the train.
When the associated end valve is closed, braking will occur in the disconnected part of the highway and the train will stop if the braking force is greater than the traction force.

When the oncoming end valve is closed, air will be released from the head of the line, due to the additional discharge of the line, braking will spread further towards the locomotive. On the freight locomotive, the brake line break alarm with sensor No. 418 is triggered and the traction is turned off.
After the additional discharge of the line stops, the driver's valve will increase the pressure in the line and the air distributors will be released to the closed end valve. Behind the end valve overlap, the supply of leaks from the main line will stop and the air distributors of the freight train will operate to full braking.

The peculiarity of cargo air distributors is that in almost all cases when the mains supply is cut off when the end valves are closed, they act on braking due to the fact that their storage tanks are disconnected from the mains by check valves, which gives a rapid decrease in pressure in the mains under the influence of leaks.

In all cases of revealing closed end valves after stopping the train, it is necessary to release the brakes with the driver's crane, open the end valve, make a short test of the automatic brakes and be sure to check the release of the brakes to the last carriage.

Braking on the train, which occurs when the operator's crane handle is in train position, is called AUTO BRAKES.

1. It can be caused by a rapid decrease in pressure in the line in cases of self-disengagement, breakage and disconnection of the hoses, breakage of the outlet from the line to the air distributor, closing (overlap) of the oncoming end valve or both end valves with the release of compressed air from the line through their control holes. This group of reasons is associated with a violation of the density of the backbone.
2. Spontaneous operation of automatic brakes is also possible with a decrease in pressure in the line in cases of overlap of the associated (backward) end valve, the formation of an ice or mechanical plug in the line.
3. Some cases of self-braking occur as a result of unreliable release of the brakes due to their malfunction.
4. Spontaneous operation of automatic brakes is possible during the transition from increased to normal charging pressure due to the accelerated rate of transition (not repaired stabilizer of the driver's crane)
5. There are also cases of self-braking of air distributors No. 483. They occur when the leakage from the brake line changes when driving along curves of a small radius or arrows, as well as when there is a sharp dynamic impact on cars with loosening of the working chambers of the air distributors or brake lines. Such actuation is most likely for the trunk section, in which the soft throttle hole is clogged, or due to the increased spring force, the soft valve does not lift and open.

Identifying the causes of spontaneous braking on the train

Spontaneous operation occurred when the train was parked, the cause of activation may be:

1. poor air permeability of the locomotive;
2. faulty or incorrectly adjusted stabilizer of the operator's crane (elimination of over charging pressure is faster than the established standards). The brakes are applied when the operator's crane handle is moved from position 1 to position 2;
3. faulty air distributor.

Identifying the causes of spontaneous operation of the brakes in a train must begin with checking the density of the train's braking network, then, having disconnected the cars (the braking system of the cars), check the locomotive.

1. Find out at what pressure in the main tanks the brakes are activated. If operation is observed at the lower pressure limit of 7.5 atm., Check the air permeability of the brake and power supply network of the locomotive.
The air permeability of the brake system is checked by opening the end valve on the locomotive at least 3 times (through the driver's valve locking device). If the pressure drops, the permeability is low, possibly freezing, clogging of the supply or brake line. Check the air flow through the blocking device. After stopping the compressors and when the pressure in the main tanks reaches at least 8 atm. On the electric locomotive, the compressors are turned off, on the diesel locomotive, the diesel is stopped. The operator's crane handle is moved to the VI position. The connecting sleeve is removed from the suspension and holding it open the end valve.
The operator's crane handle is moved to position I. The time of pressure reduction in the main tanks is measured from 6.0 to 5.0 atm., Which should be for tanks Y = 1000 liters. no more than 12 s. for the rest, the time increases proportionally.

2. If the actuation occurs within 1-2 minutes after the start of the vacation,
check the rate of elimination of overcharge and the operation of the rupture indicator
brake line, then - the density of the surge tank follows
in the following order:
make a vacation, keeping the driver's crane handle in 1 position until the pressure in the equalizing tank from 6.5 to 6.8 kg / cm2, followed by transfer to the train position. The pressure in the equalizing tank should decrease from 6.0 to 5.8 kg / cm2 in 80-120 s.
On a locomotive equipped with "TM", the signaling device during the transition from increased pressure to normal pressure should not work.
To check the density of the surge tank, charge the brake network to normal charging, move the operator's crane handle to the IV position. The density is considered sufficient if the pressure drop in the surge tank does not exceed 0.1 kg / cm2 for 3 minutes. In this case, overpressure in the surge tank is not allowed.

3. Identification of faulty air distributors.
A faulty air distributor uel No. 483 is identified by the following signs: it is triggered when the brake network is charging, when the pressure in the storage tanks begins to equalize with the line pressure (the noise in the storage tanks stops) and then periodically triggers at regular intervals.
To identify such an air distributor, it is necessary to establish in which part of the composition it is located. For this, the train is divided "in half" the brakes of the head part of the cars remain on, the rest are turned off by the end cranes. If the faulty device (the additional charging valve, the soft valve does not work satisfactorily) is in this part of the train, then when charging after 3-7 minutes, the automatic brakes will spontaneously operate, leaving a quarter of the cars turned on from the head, repeat the check.
Thus, a group of cars is installed, in which the faulty device is located. Then, with the help of disconnecting valves, the air distributors are sequentially turned off and, having identified the faulty one, they are replaced.

Spontaneous activation occurred when the train was set in motion

The most common reasons for the operation of automatic brakes are:

1. the presence of hidden air leaks in the brake system;
2. faulty air distributor, service No. 483 (sagging of the rubber seal at the valve of the additional discharge chamber of the line, insufficient rigidity or non-compliance of the valve spring with the established dimensions)

1. Leaks are detected by external signs by ear, touch, by the presence of a roller of dust, dirt, by paint rupture, in winter by the presence of frost, hoarfrost at the place of leak. When checking, it is necessary to inspect the condition of the couplings, threads, the presence of cracks, breaks in the line and supply pipes.
In addition, reliable fastening of the air duct of its branches, reservoirs and brake cylinders is of great importance for the stability of the operation of any connection. Failure of attachment entails a breakdown of the connections and, as a rule, leads to the operation of the brakes along the way.
Having identified the leak, it is necessary to make sure that it leads to the operation of the brakes along the route. The check is carried out with a crowbar, which is wound between the main line and the backbone by pressing it down. If the clutch is poorly attached to the line (on 2-3 threads), a bend occurs in the clutch joint, the leakage increases greatly, which leads to the operation of the brakes.
The quality of fastening of air ducts and brake fittings is checked by tapping the points of their attachment to the car frame with a test hammer.

2. To identify a faulty air distributor leading to
when the brakes are triggered in the train, you need to know that it comes into action due to the oscillatory movement of air in the line from a shock. Moreover, the greatest effect of identifying a faulty air distributor is obtained by tapping the sleeves (250 mm from the end valve) and the main part of the device at the time of transition from overpressure to charging (when overcharging pressure is eliminated).
After setting the minimum value for the elimination of the overcharge pressure (80 sec.), At the moment of transition from the overpressure to the charging one, it is necessary to tap with a hammer (crowbar) the sleeves and air distributors on the locomotive and the cars (along the body of the main section, the direction of the blows horizontally).
But since the time for tapping is limited by the time of elimination of the supercharging pressure, tapping must be performed at the command of the locomotive driver at a certain time interval, which is calculated by the formula:

T = Tick. x 0.08,

where T is the required tapping time (in minutes) T lick. - overcharge elimination time.

EXAMPLE: T lick - 80 s. then T = 80 x 0.08 = 6.4 minutes. that is, after 6 minutes, stop tapping and wait for the driver's command to resume the check.

In the presence of a faulty air distributor, the brakes are triggered, being in a braked state, the air distributor, after a certain period of time, releases air into the atmospheric opening of the main part. Usually, a faulty air distributor is triggered 5-6 cars before the impact on the sleeve was made.
All identified malfunctions leading to spontaneous operation of the brakes are eliminated and the brakes are fully tested, a new certificate VU-45 is issued to the driver.

Before looking for the causes of brake problems, make sure that the tires are in good condition and correctly inflated, that the wheel alignment is well adjusted and that the load is evenly distributed in the car.

When braking, the car is pulled to the side
Incorrect brake pad adjustment.
Non-simultaneous replacement of linings on both wheels of one axle.
Unequal air pressure in the tires of the front wheels.
Seizure or deep marks on the mirror of one of the front wheel brake drums.
Front brake pad damaged, wet or oily on one side.
The material of the front brake pad or the disc on the other side is badly worn out.
Front suspension parts loose or loose.
The piston is scratched or oval.
Caliper mounting bolts are loose.
Wheel bearing misaligned.
Leakage of brake fluid in one of the wheel cylinders.
Wheel cylinder piston sticking.
Blockage of the steel tube due to a dent or blockage.
Different tire pressures.
Incorrect wheel alignment angles.
Incorrect pressure regulator settings.
Defective pressure regulator.

Screeching
Front brake pads wear - noise is caused by friction of the wear sensor on the disc.
"Polished" or dirty front pads.
Dirty or scratched disc.
Support plate bent.
Weakening of the return spring of the rear brake pads.
Rear brake drum ovality.
Greasing of friction linings.
The linings are worn or foreign bodies are included.
Excessive brake disc runout or uneven wear.

Too long brake pedal travel
Lack of fluid in the master cylinder.
Air in the system.
Disc beating.
Brakes not adjusted.
Damage to the master cylinder cuff.
Fluid leaking from wheel cylinders.

Pedal falls through
Lack or absence of fluid in the master cylinder reservoir. ...
Defective master cylinder.

When the brake pedal is depressed, it springs
Air in the brake pipes.
Rubber brake hoses worn out.
The mounting bolts of the brake master cylinder are loose. Master cylinder defective.
Wrong front or rear brake pad clearance.
The outlet of the tank cap is clogged.
The rubber tubes of the brakes are deformed.
Caliper seals are soft or swollen.
Poor quality brake fluid.

The brake pedal vibrates when the brakes are applied
Wheel bearings are damaged, worn or misaligned.
The caliper is not installed correctly.
Wear and non-parallelism of discs.
Unequal thickness of all discs.
The drums are now oval.

Seized brakes
(manifested in a decrease in engine speed or excessive heating of the wheel discs after driving)
Incorrect adjustment of the output rod on the brake pedal.
Cylinder regulator blocked.
Seizure of the pistons of the working cylinders.
Front brake pads are worn.
The parking brake is not released.
Clogged brake pipes.
Incorrect pad-to-drum clearance. :
Clogged compensation hole of the master cylinder.
Swelling of the master cylinder rubber cuffs (all cylinders are not released) or wheel cylinder cuffs due to the ingress of mineral oil or gasoline into the system.
There is no free play of the brake pedal due to an incorrect position of the brake light switch.
The protrusion of the adjusting bolt of the vacuum booster relative to the mounting plane of the master cylinder is broken.

Clogged compensation hole in the master cylinder.
Master cylinder piston seized.

Rear brakes are locked under light braking

Heavy tire wear.
The braking force corrector is damaged or misaligned.

Rear brakes are locked under heavy braking
Tire pressure too high.
Heavy tire wear.
Front brake linings are contaminated with oil, dirt or water, master cylinder or caliper defective.

Reduced brake pedal travel
The thrust ring of the device for automatically maintaining the gap between the shoe and the drum does not fix the shoe in the braked state.

Incomplete return of the brake pedal after braking due to weakening of the return spring of the pedal
Sticking of the movable seat of the follower mechanism of the hydraulic vacuum amplifier when returning to the lower position after the cessation of pressing the pedal.
The return spring of the brake pads is loose or broken.
Piston sticking in wheel cylinder due to corrosion or blockage.
Swelling of the wheel cylinder seals due to the ingress of mineral oil or any other petroleum-based fluid.

High pedal effort when braking
The pads are worn out.
Oiled brake linings.
Incomplete adhesion of the brake pads.
Clogged air filter of the hydraulic vacuum amplifier.
The diaphragm of the chamber of the hydraulic vacuum amplifier is torn.
The diaphragm of the movable seat of the hydraulic booster is torn.
The ball valve of the piston of the hydraulic vacuum booster passes the brake fluid, the pedal kicks back.
Vacuum booster air filter clogged.
Seized booster valve body due to swollen diaphragm or pinched booster cap seal or protective cap.
The hose connecting the vacuum booster and the engine intake pipe is damaged, or it is loose on the fittings.
Swelling of the cylinder seals due to petrol or mineral oils entering the fluid.

Rattling or "squeak" in the brakes
The brake shield is loose.
Bad contact of the pads with the drums.
The nuts of the pad support pins are loose.

Great effort on the hand brake handle
The brake linings are oiled with brake fluid leaking from the rear wheel cylinder.

The brake drums are heated when the foot brake pedal and the parking brake lever are released
Wheel does not release.
Incorrect adjustment of the parking brake actuator.
Failure to return the pads and the manual drive expander lever to its original position due to jamming of the cables in the guide tubes.

Does not hold the parking brake
Large free play in the handbrake mechanism.

Insufficient braking performance
The brake booster is not working well.
Severe wear on the gaskets or front brake pads.
One or more pistons are jammed.
Front brake pads are dirty with oil or grease.
The new front brake pads have not yet worked in.
Worn or damaged master cylinder.
Leakage of brake fluid from wheel cylinders.
Air in the brake system.
Damaged rubber seals in the brake master cylinder. ;
The rubber hoses of the hydraulic drive system are damaged.

Spontaneous braking when the engine is running
Air leaks in the vacuum amplifier between the valve body and the protective cap: destruction or misalignment of the cover seal or poor fixation due to damage to the locking parts, wear of the seal, insufficient lubrication of the cover seal.

One wheel does not release
The brake shoe rotates tightly on the support pin.
No clearance between the pad pad and the drum due to improper installation of the automatic adjustment thrust ring.
The return spring of the rear brake pads is loose or broken.
Piston sticking in the wheel cylinder due to corrosion.
Swelling of the wheel cylinder sealing rings due to the ingress of fuels and lubricants into the liquid.
No clearance between pads and drum.
Violation of the position of the caliper relative to the brake disc when loosening the bolts fastening to the bracket.
Increased runout of the brake disc (more than 0.5 mm).

Uneven wheel braking
Shock absorbers do not work.
The camber angle of the wheels is violated (wear of the inner tread tracks).
Low tire pressure (high wear at the edges of the tread).
Increased tire pressure (high wear in the middle part of the tread).
The toe-in of the front wheels is too low (wear of the inner tread tracks).
The toe-in of the front wheels is increased (wear on the outer tread tracks).

Wheel runout
Imbalance of wheels: uneven wear of the tread around the circumference, displacement of balancing weights and tires during installation, deformation of the rim, damage to tires.
Increased clearance in wheel bearings.