MAINTENANCE OF FORKLIFTS - OD1660 - LESSON 1/TASK 1
automatically the low limit or cut in pressure that will start the
The high limit is adjusted by turning the pilot
valve adjusting plug. One full turn of the plug changes the limit by
200 psi, 1/2 turn by 100 psi and 1/4 turn by 50 psi. The high limit
is raised by screwing the plug into the body and is lowered by
screwing the plug out of the body.
(d) At this time, fill the pump up with oil and attach it to
the accumulator port on the valve.
Then pump up the valve until a
decisive click is heard, caused by the shifting of the pilot valve.
Check the gage reading.
The reading should be 1300 psi; if it is
not, then the pilot valve plug should be adjusted.
(e) After adjusting the high limit pressure, the pressure
should be allowed to leak down until another click is heard.
will happen when the low pressure reaches between 650-550 psi.
(f) While pressure testing the valve, it should be checked for
leakage from either the back port or the return port.
should be less than 60 drops per minute.
However, no leakage is
permissible from the pressure port.
It is not necessary to exceed
1900 psi for testing the pressure because system pressure is always
(4) Charging the Accumulator.
testing or charging the accumulator.
Use only dry nitrogen gas when charging the
accumulator. Exercise extreme care when testing,
charging, or otherwise servicing the accumulator.
(a) When charging the accumulator, first attach the regulator
charging kit. Then open the accumulator valve to read the pressure.
(b) Open the valve on the nitrogen bottle and set the regulator
to charge the accumulator cylinder to 275 psi.
Then close the
nitrogen bottle valve and detach the charging kit.