TM 9-4940-568-34
2-53
Table 2-7. Crane Troubleshooting (CONT).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
7. CRANE DOES NOT SWING CLOCKWISE.
WARNING
Never disconnect any hydraulic hose or part while FRS is run-
ning. Allow several minutes for pressure to relieve itself. With
FRS shut down, operate control valves fully in each direction
to relieve trapped pressure.
Before testing hydraulic system with a flow meter, always open
the pressure control valve all the way by turning the knob
counter clockwise to DECREASE. Failure to do so may cause
hydraulic lines to burst, causing personal injury.
When increasing hydraulic system pressure with the pressure
control valve, always increase pressure slowly. If pressure is in-
creased too fast, damage to hydraulic system or test set will re-
sult.
CAUTION
Checking system pressure involves putting valves into relief. Relief is
defined as a point when a needed system pressure is reached, causing
excessive pressurized hydraulic fluid to be directed to the hydraulic
reservoir.
Relief is accomplished either by operating the system in a manner
which will create relief or by using the loading valve on the flow meter,
which will simulate the operating conditions. Putting valves into relief
should be limited to no more than 10 seconds to prevent excessive heat
buildup.
NOTE
Unless called for in the test being done, all pressure tests will be done with FRS 24
V MASTER switch in the ON position, and hydraulic oil temperature at 130-150 F
(54-66 C).
Unless advised otherwise, the FRS 24V MASTER switch and the crane MAIN
POWER switch must be in the ON position for all voltage checks.
Before performing troubleshooting procedures, make sure there are no restrictions
in pressure or return lines.
