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TM 5-2420-222-34
14-13.
BACKHOE RELIEF VALVES MAINTENANCE (Con’t).
g.
ADJUSTMENT
1.
If installed, remove backhoe control valve assembly (see
TM 5-2420-222-20).
2.
Connect proof pressure tester to valve head (21).
3.
Using 12 3/4 in. -14 NPT pipe plugs, plug crowd valve (19),
bucket valve (18), swing valve (17), boom valve (16), and
two stabilizer valves (15 and 20).
4.
Using proof pressure tester, pump up hydraulic pressure to
1800 psi (12,411 kPa) and check for leaks. Tighten all
leaking connections. If leaking does not stop, replace relief
valve (1).
NOTE
All relief valves are adjusted the same way. Repeat steps 5 through 9 for each
relief valve as required.
5.
Push clevis rod end (14) down to check top relief valve (1) or pull up to check bottom relief valve in crowd valve
(19), swing valve (17), or boom valve (16).
WARNING
Relief valves are stamped with pressure limit. Crowd, swing, and boom (lower)
relief valve pressure limit is 2375 psi (16,376 kPa). Boom (raise) relief valve
pressure limit is 3500 psi (24,133 kPa). Do not exceed stamped pressure limit.
Serious injury to personnel may result.
6.
Using proof pressure tester, pump up hydraulic pressure until relief valve (1) opens or pressure limit of relief valve
is reached.
TA701599
14-70
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