Pilot valve
The pilot valve is electrically operated by two solenoid
coils, which are energized by the integrated shift
module. Oil from the pilot valve is used to cycle the
shift valve spool, which in turn causes the intensifier to
cycle. Each solenoid coil connector LED lights up when
that solenoid coil is energized.
The most common pilot valve problems are leaks due
to worn o-rings, a failed solenoid coil, and sticking of
the spool in the body due to contaminated oil.
See Cleaning a contaminated hydraulic system.
Service steps
WARNING
Place the main electrical disconnects in the OFF
position and bleed down all high-pressure lines.
Place Out of Service tags on the main electrical
disconnects and lock them out. Failure to do so can
result in equipment damage or injury to personnel.
1. Shut down the system.
Note: When working on the valves, drain the oil
from the reservoir into a clean container able to hold
37 gallons (140 L).
2. Remove the solenoid coil connectors by unscrewing
their central screws and unplugging the connector
bodies from the solenoid coils.
•
Check solenoid coil continuity using an ohm
-
meter across the two channel-shaped pins.
Electric resistance should be approximately
19 ohms. The third, flat pin is the ground
connection.
3. Remove each solenoid coil by unscrewing the large
black knob, removing the o-ring, and sliding the so
-
lenoid coil off its core.
4. Unscrew each core using a wrench on the two flats
close to the valve body (¾ in./19 mm A/F). Inspect
the core o-ring for damage.
Remove the spring and notched washer uncovered
on each side.
5. With a finger on each end of the pilot valve spool,
slide the spool from side to side. The spool must
move smoothly through its full stroke. If the spool
catches or is jammed, you must replace the pilot
valve.
62 | M-390 © Flow International Corporation
HYPERJET™ 94i-S AND 94i-D PUMPS
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