Disc Brake Cooling System; Brake/Hoist Return Oil Manifold - Komatsu 930E-2 Shop Manual

Disc Brake Cooling System

When the hoist control valve is in the float or hold
position, oil is supplied by the hoist valve to the disc
brake assemblies located at each wheel to remove heat
generated during service brake application.
Oil supplied to the rear wheel brakes flows from the
hoist valve (10, Figure 2-6) to the Brake/Hoist Return
Oil Manifold (8), to the brake assemblies and is then
returned to the Brake/Hoist Return Oil Manifold and the
hydraulic tank (7). Oil supplied to the front wheel
brakes is routed from the hoist valve to an oil/water heat
exchanger (1) before entering the brake assemblies.
The front brake oil is then returned to the Brake/Hoist
Return Oil Manifold and then the hydraulic tank. In
addition, the front brake cooling oil is used to lubricate
the front wheel hub bearings.
Brake cooling circuit pressure is limited by orificed
regulator valves located in the Brake/Hoist Return Oil
Manifold. Figure 2-5 shows the piping and flow of oil
through the Brake/Hoist Return Oil Manifold. The inter-
nal check valves crack open at 35 PSI (241 kPa). Their
opening pressure will be slightly higher as flow through
it increases.
Refer to Section "J" for information regarding opera-
tion of the brake system.
L2-6
FIGURE 2-5. BRAKE/HOIST RETURN OIL MANIFOLD
1. Rear Brake Return
2. Rear Brake Supply
3. Rear Brake Supply Press.
4. Front Brake Supply Press.
5. Rear Brake Cooling Oil
(From Hoist Valve)
6. Return From Hoist Vlv.
7. Return From Hoist Vlv.
8. Manifold
9. Front Brake Bypass
Hydraulic System
10. Rear Brake Return
Press.
11. Hoist Return Press.
12. Front Brake Return
Press
13. Rear Brake Return
14. Rear Brake Return
15. Hoist Return to Tank
16. Front Brake Return
17. Front Brake Return
18. Front Brake Return
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