TM 10-3930-675-24-2
HYDRAULIC SYSTEM TEST POINT PROCEDURES - CONTINUED
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TEST POINT NO. 1: BRAKE ACCUMULATOR NO. 1
NOTE
Test point no. 1 provides a means to check brake charging valve opening pressure and accumulator
pre-charge nitrogen pressure within brake circuit no. 1.
1.
Open both brake system drain valves (2) slowly until pressure is completely drained.
2.
Connect hydraulic test gage to test point no. 1.
2
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3.
Close both valves (2).
4.
Start engine. Pressure will jump to pre-charged nitrogen pressure in accumulators; 1,230 to 1,300 psi (85 to 90 bar).
Pressure will then build to 2,540 to 2,610 psi (175 to 180 bar).
5.
Pump brake pedal. Pressure will slowly drop to 2,000 psi (140 bar) and back to 2,540 to 2,610 (175 to 180 bar) when
pumping is stopped.
6.
Shut engine off. Open both brake system valves slowly and note point at which pressure drops off completely. Drop-off
point is pre-charged nitrogen pressure in accumulators; 1,230 to 1,300 psi (85 to 90 bar).
7.
Disconnect hydraulic test gage from test point no. 1. Close both valves (2).
TEST POINT NO. 2: BRAKE ACCUMULATOR NO. 2
NOTE
Test point no. 2 provides a means to check brake charging valve opening pressure and accumulator
pre-charge nitrogen pressure within brake circuit no. 2.
1.
Open both brake system drain valves (2) slowly until pressure is completely drained.
2.
Connect hydraulic test gage with adapter to test point no. 2.
3.
Close both valves (2).
4.
Start engine. Pressure will jump to pre-charged nitrogen pressure in accumulators; 1,230 to 1,300 psi (85 to90 bar). Pres-
sure will then build to 2,540 to 2,610 psi (175 to 180 bar).
5.
Pump brake pedal. Pressure will slowly drop to 2,000 psi (140 bar) and back to 2,540 to 2,610 (175 to 180 bar) when
pumping is stopped.
6.
Shut engine off. Open both brake system valves slowly and note point at which pressure drops off completely. Drop-off
point is pre-charged nitrogen pressure in accumulators; 1,230 to 1,300 psi (85 to 90 bar).
7.
Disconnect hydraulic test gage from test point no. 2. Close both valves (2).
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