3-8-proverka-tormoznojj-sistemy-i-scepleniya.html
3.8. Check of the brake system and coupling
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The dust which is formed as a result of wear of slips and accumulating on components of the brake mechanism may contain asbestos hazardous to health. Do not blow this dust by means of compressed air and do not inhale it! Do not use for removal of dust solvents on the basis of gasoline. |
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Except checks through the established time intervals a condition of brake mechanisms it is necessary to carry out every time at removal of wheels or at emergence of signs of malfunction in the brake system. Check of level of brake fluid is described in the Section Check of Levels of Liquids, control of leaks. |
Signs of malfunctions in the brake system
Any of the listed below signs can indicate potential defect of the brake system:
- When squeezing a pedal of a brake during the movement the car "takes away" in one party;
- Brake mechanisms when braking make the scraping or squealing sounds;
- The pedal of a brake has the excessive course;
- The pedal of a brake pulses (it normally only during the work of the ABS system);
- Leak of brake fluid is observed (tires, usually noticeable on inside, or wheels)
In case of detection at least of one of these signs immediately examine the brake system.
Brake lines and hoses
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In the brake system metal brake tubes, except for the flexible reinforced hoses at wheels are generally used. Regular survey of all these lines is very important. |
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- Park the car on the flat platform.
- The car also establish to Poddomkratta it on props then remove wheels. Check of vacuum hoses is described in the Section Check of a State and Replacement of Hoses and tubes in a motive compartment, localization of leaks.
- Check all brake lines and hoses for existence of cracks and attritions in their external covering, and also leaks, swellings and deformations. Check brake hoses in forward and back parts of the car for existence of signs of a softening, cracks, deformations or wear as a result of friction about other details. Check all nipple connections for existence of signs of leaks and make sure of reliability of all fixture of brake lines.
- Bend hands in one and other parties a brake hose to reveal damages. It is not necessary to twist hoses.
- Turn a steering wheel to the right and to the left against the stop. Make sure that hoses at the same time do not touch car design elements.
- At detection of leak of liquid from brake lines or their damages of leak it is necessary to eliminate immediately. For more detailed description of the procedure of repair of the brake system address the Head the Brake system.
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Check of thickness of brake shoes and disks
Disk brake mechanisms
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- The car also establish to Poddomkratta it on props then remove the corresponding wheel.
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Experience shows that owing to availability of dirt on the edge of the road wear of brake shoes of the right wheel is more, than left. Therefore for check it makes sense to remove a forward right wheel. |
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- Measurement of thickness of a block of a disk brake is performed through a special control window in a support. If thickness of a frictional overlay of a block makes less than 3 mm, replace all blocks of both brake mechanisms of wheels of this axis (see the Head the Brake system).
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As a rule, 1 mm of wear of an overlay of a brake shoe corresponds to, at least, 1000 km of a run under adverse service conditions. In usual conditions of a slip are erased much more slowly. |
- Check supports of brake mechanisms for existence of leaks. At detection of leaks urgently repair a support.
- Visually check brake disks from internal and outer side for existence of furrows, a rust and cracks. Replace defective components.
- Measure thickness of brake disks in several places by means of a micrometer or a special caliper. It is also possible to measure thickness of a brake disk by a usual caliper, having enclosed from each its party a lining of the known size (for example, two coins), and then having subtracted thickness of linings from the measured value.
- Compare minimum of the received results to requirements of Specifications to the Head the Brake system. If the limit of wear is reached, replace surely both brake disks. The brake disk should be replaced also at big cracks or deep furrows on a working surface.
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Boots of the parking brake
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- Using instructions of the Head the Brake system, remove back brake disks.
- Measure thickness of frictional slips on boots of back brake mechanisms and examine them on existence of signs of pollution by brake fluid or lubricant. If the slip has thickness within 1.5 mm over heads of rivets or the metal basis in the thinnest place, replace all boots. Also the boots polluted by brake fluid or lubricant are subject to replacement also burst, zapolirovanny to gloss. The procedure of replacement is described in the Head the Brake system.
- Check a condition of the coupling and holding springs of boots, and also the adjusting mechanism. Make sure that all these components are correctly installed and are in working order. The worn-out or deformed springs can serve as the reason of premature wear of frictional slips.
- Check wheel cylinders for existence of signs of leaks, having accurately removed protective rubber covers. Existence of insignificant traces of moisture under covers is allowed. If under them brake fluid is found or it follows from the wheel cylinder, then cylinders should be repaired or replaced capitally (address the Head the Brake system).
- Check drums for existence of deep scratches, furrows, cracks and superheated sites which look as the decoloured spots. If the revealed defects cannot be eliminated by means of an emery paper, the drum should be pierced in a workshop.
- Following indications of the Head the Brake system, establish brake disks.
- Establish wheels. If check of the parking brake is required, do not lower the car on the earth.
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Check of reliability and course of the lever of the parking brake
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- The simplest way of check of operation of the parking brake is installation of the car on a steep slope with the cocked brake and transmission in neutral situation (when checking it is necessary to be in the car). If the parking brake does not keep the car from rolling, it is necessary to make its adjustment (see the Head the Brake system).
- Car back also establish to Poddomkratta it on supports.
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Previously it is recommended to cock carefully at a speed of 40 km/h the parking brake to feeling of easy braking. Then, supporting the specified speed, cock the lever on one click and be passed about 400 m. After that release the parking brake and let's it cool down. |
- Tighten the parking brake on 5 teeth. Turn wheels by hand – easy resistance from action of a brake has to be felt.
- Tighten a brake on 6 teeth. At the same time wheels should not be turned manually. If for braking creation the lever is required to be cocked further, adjust the parking brake (see the Head the Brake system).
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Check of the vacuum amplifier of brakes
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- At the switched-off engine several times squeeze out a brake pedal, – with each pressing its course has to decrease.
- At the squeezed-out pedal of a brake start the engine, – the pedal has to move down.
- Holding a pedal of a brake of squeezed out, kill the engine. If when keeping a pedal within 30 seconds its course does not change, the vacuum amplifier as it should be.
- If one of the listed above checks yielded unsatisfactory result, repair or replace the vacuum amplifier (see the Head the Brake system).
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