BENDIX M-21-M-22 ANTILOCK MOD ASSY Manual de servicio descargar pdf (Pagina 10)

Balanced: No. 2 circuit portion

When the air pressure on the No. 2 side of the relay piston approaches that being

delivered on the No. 1 side of the relay piston, the relay piston moves, closing the No. 2

inlet valve and stopping further flow of air from the supply line through the valve. The

exhaust remains closed as the No. 2 delivery pressure balances the No. 1 delivery

pressure.

When applications in the graduating range are made, a balanced position in the No. 1

portion is reached as the air pressure on the delivery side of the No. 1 piston equals

the effort exerted by the driver’s foot on the treadle. A balanced position in the No. 2

portion is reached when air pressure on the No. 2 side of the relay piston closely

approaches the air pressure on the No. 1 side of the relay piston.

When the brake treadle is fully depressed, both the No. 1 and the No. 2 inlet valve

remain open and full reservoir pressure is delivered to the actuators.

SERVICE CHECKS

Operating Check

Check the delivery pressure of both No. 1 and No. 2 circuits, using test gauges known

to be accurate. Depress the treadle to several positions between the fully released and

fully applied positions, and check the delivered pressure on the test gauges to see

that it varies equally and proportionally with the movement of the brake pedal.

After a full application is released, the reading on the test gauges should fall off to zero

promptly. It should be noted that the No. 1 circuit delivery pressure will be about 2 PSI

greater than the No. 2 circuit delivery pressure, with both supply reservoirs at the

same pressure. This is normal for this valve.

IMPORTANT: A change in vehicle braking characteristics or a low pressure warn-

ing may indicate a malfunction in one or the other brake circuit, and although

the vehicle air brake system may continue to function, the vehicle should not be

operated until the necessary repairs have been made and both braking circuits,

including the pneumatic and mechanical devices, are operating normally. Always

check the vehicle brake system for proper operation after performing brake work

and before returning the vehicle to service.

LEAKAGE CHECK

1. Make and hold a high pressure (80 psi) application.

2. Coat the exhaust port and body of the brake valve with a soapy solution.

3. Leakage permitted is a one inch bubble in 3 seconds. If the brake valve does not

function as described above or leakage is excessive, replacement is recommended.

Air Brake System

Revised 11/15/99

1 2 ... 5 6 7 8 9 10 11 12 13 14 15 ... 31 32

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BENDIX M-21-M-22 ANTILOCK MOD ASSY Manual de servicio Pagina 10