TROUBLESHOOTING 777 SERVICE MANUAL
10-50 Published 10-01-2012, Control # 045-08
Test 20 – Checking Hydraulic Brake Pressure
The hydraulic brake pressure is obtained by activating the
desired system brake while measuring the hydraulic
pressure at the brake control valve or disc brake housing
with a 0-500 psi gauge. Both test ports will yield the same
measurement. To test at the control valve, connect the
gauge between the flexible hose and the adapter fitting at
the top of the valve. To test at the disc brake housing,
connect the gauge between the flexible hose and the 90°
elbow at the disc brake housing. Acceptable hydraulic brake
pressure is 300 psi or greater. If the pressure is less than
300 psi, the system pump charge pressure should be
checked. See Test 15. If the charge pressure is adequate,
repair or replace the brake control valve.
Item Description Item Description
1 Travel 2-speed solenoid valve 7 Swing lock out solenoid valve
2 Travel disc brake solenoid valve 8 Electrical DIN connector
3 Rear drum disc brake solenoid valve 9 Load drum disc brake housing
4 Front drum disc brake solenoid valve 10 90° elbow
5 Swing disc brake solenoid valve 11 Flexible hose
6 Swing lock in solenoid valve
FIGURE 10-25
P515a
P572
1 2 3 54 6
10
11
5
8
7
9
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