STEP 3 - Pump or Relief Valve ..
Ti high pressure cannot be obtained in STEP 2 by running the pump against
the relief valve, further testing must be conducted to see whether the fault I
inthe pump or in the relie valve. Proceed ns follow:
‘posable, disconnect the reservoir return line from the relief valve at point
H. Atlach a short length of hose to the relef valve outlet. Hold the open end of
this hose over the reservoir filer opening ao Ihe rate of ol low can be observed.
Start the pump and run the reel valve adjustment up and down while observ
ing the flow through the hose. If the pump is bad. there will probably be a fui
stream of oil when the relief adjustment ie backed off but this flow will dim:
{sh or stop as the adjustment in increased
Fa flowmeter is available, the flow can be measured and compared with the
pump catalog rating. a flowmeter is not available, the rate of How on small
umps.can be measured by discharging the hose into a bucket while timing with
a watch, For example, ia volume of 10 gallons is collected in 15 seconds, the
‘Dumping rate à 40 GPM, ete
the gauge pressure does not rise above a low value, say 100 P*
fou docs not substantially decrease as the reel v
‘ened, the relier valve is probably at fault and should be el
structed in STEP 5. Ifthe oil substantially decreases as the relict valve ad
justment is tightened, and ifonly alow or moderate pressure can be developed,
this indicates trouble inthe pump. Proceed to STEP 4
STEP 4- Pump
Ifa full stream of oi is not obtained in STEP 3, or if he stream diminishes
as the relief valve adjustment e tightened, the pump is probably at fault. Aw
Suming that the suction strainer has already been cleaned and the inlet plumb:
ing has been examined for air leaks, as in STEP À, the ol a nipping across the
1 elements inside the pump. This can means wora-out pump, or Wo
an Oi temperature. High shippage inthe pump will cause the pump to run
considerably hotter than the oil reservoir temperature. In normal operation,
With a good pump, the pump ease will probably run about 20°F above the reer:
oir temperature, greater than this, exce lppaye, uned by wear, may be
‘Check alo for slipping bets, sheared shat pin or ke, broke sha broken
coupling, or loosened net screw
STEP 5 - Relief Valve ...
the test in STEP 3 has indicated the trouble tobe in the relief valve, point
D. the quickest remedy is to replace the valve with one known to be good. The
faulty valve may later be disassembled for inspection and cleaning: Pilot-oper
ated relie valves have small orifices which may be blocked with accumulations
öfdirt Blow out all passages with an air hose and run a small wire through or.
tien Check slo for free movement of the spon. in relief valve with pipe
thread connections in the body the spool may bind pipe ftings are over.
toned: If possible, test the spool for bind before unscrewing threaded connections
{rom the body. or screw in Rttings tightly during inspection ofthe valve
STEP 6 - Cylinder
[the pump will deliver full pressure when operating across the relief val
in STEP 2 both pump and reli valve can b lered good, and the trol
Is further downstream. The cylinder should be tested first for worn-out or detec:
tive packings by the method described on page 7.
STEP 7 - Directional Control Valve
Tithe cylinder has been tested (STEP 6) and found to have reasonably tight
isi seal he wy vale sald be ehecked next Although ex ol ale
pen, an excessively worn valve spool can slip enough al 1 prevent build-a
of maximum pressure: Symptom of this condition are a Tons ot cylinder spect
together with eu sn building upto fall pressure even with the oli valve
‘adjusted toa high setting. This condition would be more likely to vecur with
high pressure pumpe offow volume output, and would develop gradually over a
long period of me, Foursway valves may be tested by the method described on
page
‘Other Components
eck other components such as bypass flow controls, hydr
Solenoid way valten ofthe pilotoperated type with tandem or 0
Spools may not Rave sulticiont ilot pressure fo shit the spon!