Tr
oublesh
ooting
4 - 1
Troubleshooting
EP800AD (Acrobat™ HPU)
TROUBLESHOOTING
HPU Motor Does Not Shut Off
Is the black dump valve knob fully closed?
No:
• Close it tightly clockwise.
Does the unit have adequate hydraulic fluid level?
No:
• Add hydraulic fluid. Refer to the
section of this manual
for fluid recommendations.
Does the unit run much longer than it should and/or have a very
short cycle time?
Yes:
• Normal cycle time is on for 5 - 7 seconds and off for 30+ seconds
(depending on temperature). If the cycle time is much shorter and there
is not a hydraulic leak, then the pump may be working, but leaking
internally. Replace pump. Refer to
in the Service/Repair
section of this manual.
• The accumulator may have lost its charge. Contact McElroy Technical
Support or McElroy Certified Mechanic.
If the motor is running continuously this means either there is no pressure building up on the system pressure
side of the hydraulic system or the pressure switch circuit is not functioning correctly. Either way the HPU motor
cannot run very long before overheating. Please take precaution to avoid overheating when troubleshooting if
the motor will not shut off.
Does the unit have adequate system pressure?
No:
• Check hydraulic system for bypass/leak. Check HPU main pressure
relief, it should be set to 1/2 turn counter-clockwise.
Does the motor shut off when the pressure switch is unplugged?
No:
• SSR is defective.
Yes:
• Check
• Check pressure at pressure switch port with a test gauge.
• Check hydraulic system leakage by inspecting/cleaning
and
carriage spool valves.
