TM 5-3895-346-14
HYDROSTATIC SYSTEM
TROUBLESHOOTING
CAUSE
INDICATED BY
REMEDY
G.
Internal damage
Low or zero charge
1. A check of the individual
to pump or motor
pressure. Charge pres-
unit leakage is necessary to
or both
sure may also fluctuate
determine whether the damage
rapidly or fall to or
is in the pump(s) or motor(s).
near zero when maximum
system pressure is
Before proceeding to replace
reached
either unit, use the following
procedure:
Maximum system pressure
capability in both for-
ward and reverse is
less than normal high-
pressure relief valve
setting
Pieces or flakes of
A. To check fixed displace-
brass in reservoir or
ment motors:
filter
Noisy unit (pump or
(1) Remove the charge pres-
motor)
sure relief valve cap in the
motor manifold, remove the
charge relief spring, insert
a solid shim of sufficient
length in place of the spring
and reinstall cap. This will
block the relief valve in a
fully closed position.
(2) Remove the motor case
drain line where it connects
to the pump case port and
seal pump case with the prop-
er size threaded plug.
(3) Insert a suitable flow
measuring device capable of
measuring at least 100%
charge pump flow in the motor
case drain line (See Note.)
Complete the circuit by dis-
charging the line to the
reservoir.
(4) Start the prime mover
and run the pump in neutral
at maximum speed.
(5) Engage the pump control
slowly and maintain the high-
est possible system pressure.
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