
rev. 1/16/2017 CBS, MANUAL.doc
Copyright 2017 Vestil Manufacturing Corp. Page 15 of 20
Air in the hydraulic circuit can also cause the velocity fuse to activate although no failure has occurred. To reset the
velocity fuse, activate the pump by jogging the raise button. Immediately after resetting the velocity fuse, fully lower the
forks. Cycle the forks all the way to the top of the mast and back down several times to purge air from the system.
AIR BLEED PROCEDURE:
If the forks descend very slowly or do not lower, air probably is trapped in the hydraulic circuit and must be bled from
the system. To bleed air from the circuit:
1.) Completely unload and lower the forks.
2.) Loosen the bleeder screw at the top of the cylinder approximately 1/4 to 1/2 turn to allow trapped air to escape. Jog the
motor to push air out of the system.
3.) When air is no longer present in the cylinder, only clear hydraulic fluid will flow from the bleeder screw opening.
4.) Retighten the bleeder screw.
DC-POWERED HYDRAULIC SYSTEM TROUBLESHOOTING GUIDE
Before performing maintenance on this product, unload the forks and completely lower the carriage.
Observation Possible Cause Remedy
1. Unit does not raise, motor does not run a. Low battery voltage. (Check light)
b. All chassis connections to negative post
of battery not made well.
a. Recharge battery
b. Check and tighten or clean connections
if necessary.
2. Unit does not raise but motor is running
or humming.
c. Voltage at motor terminals might be too
low to run pump at existing load.
d. Fluid level in reservoir is low.
e. Load exceeds capacity requirements.
Relief valve is allowing hydraulic fluid to
flow back into the reservoir.
f. Suction filter is clogged, starving pump.
g. Suction line may be leaking air, due to
loose fittings.
h. Filter/Breather cap on tank might be
clogged.
i. Lowering solenoid valve might be
energized by faulty wiring or might be stuck
open.
j. Hydraulic pump might be inoperative.
c. Measure voltage at motor terminals or
as near as possible, while pump is running
under load. Check for loose connections.
d. Add fluid. Refer to Owner's Manual for
proper fluid levels.
e. DO NOT CHANGE RELIEF VALVE
SETTING. Instead, reduce the load to
rated capacity.
f. Remove and clean.
g. Inspect all fittings for proper tightness.
h. Remove and clean.
i. Remove lowering solenoid valve. Check
and clean. (Refer to “Lowering Solenoid
Valves”.)
j. Disconnect hydraulic line at power unit.
Put pressure line in a large container and
operate the pump. If no output, check the
pump motor coupling which may be
defective, and correct as necessary. If
pump is worn, consult factory for
replacement parts.
3. Unit rises too slowly.k. Foreign material stuck in down solenoid
valve, causing some fluid to flow back into
the reservoir.
l. Foreign material clogging suction filter, or
breather cap, or a hose is pinched.
m. Low motor voltage.
n. Unit overloaded.
o. Inoperative pump.
k. Lower the deck. Remove the down
solenoid valve and clean. (Refer to
Hydraulic Section of Owners Manual).
l. Correct as necessary. (See also, 2(f),
(h)).
m. See 2 (b)
n. See 2 (e)
o. See 2 (j)
4. Motor labors or is excessively hot. p. Voltage may be low.
q. Oil starvation causing pump to bind &
high internal heat develops. If this occurs,
pump can be permanently damaged.
r. Binding cylinders.
p. See 2 (b)
q. See 2 (d), (f), (g), (h), (j)
r. Align cylinders correctly.
5. "Spongy·or "Jerky·unit operation. s. Fluid starvation.
t. Air in system.
s. See 2 (d), (f), (g), (j)
t. See air bleed procedure (p. 15).
6. Unit lowers too slowly when loaded.u. Lowering solenoid valve filter screen
clogged.
v. Pinched tube or hose.
w. Foreign material in flow control valve.
x. Binding cylinders.
u. Remove lowering solenoid valve and
clean filter screen.
v. Correct as necessary.
w. Remove and clean flow control valve.
Refer to Hydraulic System Diagram on p.
14).
x. Align cylinders correctly.