BENDIX TW-12 CONTROL VALVE Руководство - Страница 2
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POWER
STEERING
GEAR
RETURN
HYDRAULIC
RESERVOIR
RETURN
POWER
STEERING
PUMP
™
FIGURE 2 - TW-12
CONTROL VALVE HYDRAULIC PARK SYSTEM
™
The TW-12
valve delivery port is open to its return port
through a passage in the center of the piston.
Parking Brakes Released
™
When the TW-12
control valve plunger is depressed by the
cam action of the lever (Figure 1) the piston contacts the
inlet valve, closing the return passage. Continued piston
movement pushes the inlet valve off its seat in the body,
allowing hydraulic fluid to flow through the valve and out the
delivery port.
SERVICE CHECKS
GENERAL
Read the "General Safety Guidelines" presented in this
manual before beginning any testing or service procedure.
With the TW-12
™
control valve installed in the vehicle brake
system, proper valve operation can only be observed by the
reaction of the system and components controlled by the
™
TW-12
valve. If malfunction or internal leakage is suspected
or specific operational and leakage testing is desired, the
TW-12
™
valve must be removed and bench tested. Bench
™
testing of the TW-12
pressure regardless of its application or the braking media
used in the vehicle brake system.
OPERATING AND LEAKAGE TESTS
Function test the TW-12
system by starting the engine and warming the vehicle brake
system for 5 minutes. Move the lever cam from one extreme
2
OUT
™
TW-12
CONTROL
IN
VALVE
DELIVERY
SUPPLY
DELIVERY
RETURN
OUT
valve is accomplished using air
™
valve while it is installed in the
IN
OUT
MASTER
CYLINDER
TO SERVICE
BRAKES
SUPPLY
CONTROL
DELIVERY
™
HR-1
HYDRAULIC
RETURN
RELAY
position to the other three times and observe that the
components controlled by the TW-12
promptly to the ON then OFF condition. Inspect the exterior
of the TW-12
hydraulic brakes, no fluid leakage should be noted. Pay
particular attention to the area around and beneath the lever
cam.
1. When bench testing the TW-12
small reservoir volume to the delivery port with an air
gauge installed.
Note: 6-8 feet of ½" tubing or hose could be
used in lieu of a small reservoir.
2. Apply a 120psi air pressure source to the supply port
and move the lever cam to the applied and released
position three times. Note that delivered air pressure is
the same as supply air pressure in the applied position
and that air is promptly exhausted in the released
position.
3. With the TW-12
and 120psi at the supply port, apply a soap solution to
the return port and around the supply port cap nut.
Leakage should not exceed a 1" bubble in less than 5
seconds (100 SCCM) at the return port. No leakage is
permitted at the cap nut.
4. Place the valve in the applied position and again apply a
soap solution to the return port. Leakage should not
exceed a 1" bubble in less than 5 seconds (100 SCCM)
at the return port.
HYDRAULIC
BRAKE
BOOSTER
IN
IN
™
™
™
valve. If the TW-12
valve is used to control
™
control valve, attach a
™
control valve in the released position
HYDRAULIC
SPRING BRAKE
ACTUATOR
HYDRAULIC
SPRING BRAKE
ACTUATOR
control valve function