11.4. Check of serviceability of functioning of the vacuum amplifier of brakes
The checks which are carried out without use of the special equipment
Step 1
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- At the killed engine several times squeeze out a pedal of a foot brake.
- Squeeze out a pedal and, holding it pressed, start the engine, at the serviceable vacuum amplifier the pedal has to "fail" slightly right after start implementation.
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Step 2
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- For one-two minutes will start the engine, then again muffle it.
- Several times squeeze out a pedal of a foot brake with usual effort, - if with each pressing the course of a pedal is reduced, therefore, the vacuum amplifier functions regularly.
- In case of identification of a problem check a condition of the control valve and a connecting vacuum hose, make necessary corrections, then repeat check.
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Step 3
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- Start the engine, squeeze out a pedal of a foot brake with usual effort and, holding it pressed, kill the engine.
- Continue to hold a pedal pressed within about 30 more seconds, - if height of provision of a pedal does not change, therefore, the vacuum amplifier functions regularly.
- In case of identification of a problem check a condition of the control valve and a connecting vacuum hose, make necessary corrections, then repeat check.
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The checks which are carried out with use of measuring instruments
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- Connect measuring instruments to the brake amplifier.
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Check of tightness without loading
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- Start the engine and you do not suppress it until depression depth in the brake amplifier does not reach a point And = 66.7 kPa (500 mm of mercury.), - do not squeeze out a pedal of a foot brake.
- Kill the engine and track indications of the vacuum gage, - the speed of decrease in depth of depression in the serviceable amplifier makes no more than 3.3 kPa in 15 seconds. At identification of signs of violation of tightness it is necessary to check a condition of the control valve, a vacuum hose, to estimate quality of a welded seam of the case, to make sure of absence of damage of a diaphragm and signs of development of leaks through a plate, a sealant and the dish-shaped valve. In case of need replace assembly of the vacuum amplifier.
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Check of tightness under loading
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- Start the engine, squeeze out a pedal of a foot brake with effort of 20 kgfs and, without releasing it, wait for lowering of depth of depression in the brake amplifier to a point In = 66.7 kPa (500 mm of mercury.).
- Kill the engine and track indications of the vacuum gage, - depression falling speed besides should not exceed 3.3 kPa for 15 pages. In case of need make the corresponding recovery repair, or replace the amplifier.
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Check of hydraulic pressure
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- At the killed engine (depth of depression of 0 mm of mercury.) squeezing of a pedal of a foot brake with effort of 20 kgfs has to lift pressure in a hydraulic path to value of 1177 kPa (12 kgfs/cm2), - consider the indication of the manometer.
- Start the engine and wait for lowering of depth of depression to value of 66.7 kPa (500 mm of mercury.), then consider the indication of the manometer, - the required value makes 6867 kPa (70 kgfs/cm2). The faulty vacuum amplifier replace.
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Check of a condition of the control valve
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- Disconnect a vacuum hose from assembly of the brake amplifier.
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- The control valve is pressed in a hose and the direction of its installation in the last is shown by the arrow applied on a hose surface.
- Blow in a hose, - air has to pass freely in the direction of the engine, its podsasyvaniye in the direction of the brake amplifier should not be represented possible. The faulty valve is subject to replacement.
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