Brake Circuit Check-Out Procedure - Komatsu 930E-2 Shop Manual

BRAKE CIRCUIT CHECK-OUT PROCEDURE

The brake circuit hydraulic pressure is supplied from
the steering circuit at the bleed down manifold. Some
brake system problems, such as spongy brakes, slow
brake release, or abnormal operation of the overhead
display panel mounted "Low Brake Pressure" warning
light can sometimes be traced to internal leakage of
brake components. If internal leakage is suspected,
refer to Brake Circuit Component Leakage Test.
1. Rear Brake Accumulator
2. Charging Valve
3. Front Brake Accumulator
4. Charging Valve
5. Relief Valve (Hoist-Power Down)
6. Hoist Pilot Valve
7. Dual Relay Valve
8. Differential Pressure Sw.
9. Park Brake Release Press. (PK2)
10. Brake Cabinet
J04025
FIGURE 4-1. HYDRAULIC COMPONENTS CABINET
11. Brake Lock Shuttle Valve
12. Brake Manifold
13. Pressure Reducing Valve (PR)
14. Brake Lock Solenoid (SV1)
15. Park Brake Solenoid (SV2)
16. Front Brake Accum. Bleed Valve
17. Automatic Apply Valve
18. Low Accum. Test Port (LAP1)
19. Rear Brake Accum. Bleed Valve
Brake Circuit Checkout
NOTE: If internal leakage within the steering circuit is
excessive, this also may contribute to problems within
the brake circuit. Be certain that steering circuit leak-
age is not excessive before troubleshooting brake
circuit. For Steering Circuit Test Procedure, refer to
Section "L", Hydraulic System.
20. Low Brake Pressure Switch
21. Park Brake Pressure Switch
22. Stop Light Pressure Switch
23. Brake Lock Degradation Switch
24. Rear Brake Pressure Test Port (B1)
25. Front Brake Pressure Test Port (B2)
26. Manifold
27. Brake Warning Delay Timer
28. Brake Warning Relay
J4-1