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Cylinders: It is advisable to replace a cylinder
rather than try to repair it, although seal kits are
available. Minute scratches and nicks need to be
repaired with proper equipment. Failure to do so will
cause premature failure of new seals.
Replace cylinder if
tests indicate failure.
Failure to do so may
result in serious
bodily injury and/or
property damage.
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Troubleshooting:
Replacement of the
cylinder(s) is unnec-
essary unless plat-
form drift (failure to
hold the platform in a
raised or folded
position) occurs or a
loaded platform fails
to raise.
The cylinder should
be replaced if any
external leakage from
the rod seals is
visible. The cylinder
should also be
replaced if there is
any internal leakage
from the piston seals.
Even the slightest
amount of drift could
result in a potentially
hazardous situation.
The following proce-
Whenever replacing a
hydraulic cylinder or
seals and/or testing
for oil leakage,
lower platform fully.
Failure to do so may
result in serious
bodily injury and/or
property damage.
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dures will indicate internal leakage.
Internal Leakage Test No. 1:
a. Read warnings at left! Lower platform fully.
b. Raise platform fully, fold and continue to press
FOLD switch 5 to 10 seconds after fully folded.
c. If a continuous flow of oil from a cylinder (piston
end) is visible in the clear (yellow) return line
during the retract mode, replace the cylinder.
Black Return Line: Remove reservoir cap to look
for continuous flow of oil. Note: Movement of a
slight amount of seal lubrication oil or air bubbles
in the return line is normal.
Note: If oil leakage is not visible when conducting
Internal Leakage Test No. 1, but the platform drifts
(any measurable descent whatsoever), perform
Internal Leakage Test No. 2.
Internal Leakage Test No. 2:
a. Place load (200 to 250 lbs.) on platform.
b. Raise loaded platform fully.
c. Allow the loaded platform to set in the raised
position overnight or longer.
d. If any measurable descent is visible, refer to
Section 8.40 of the Troubleshooting Diagnosis
Chart for remedies.
Systems Descriptions
Manual Backup Pump: The manual hydraulic
backup pump system is used to unfold, lower, raise
and fold the platform in the event of electrical failure.
See the lift posted Manual Operating Instructions
Decal for operating procedures. See the Hydraulic
Diagrams and Parts Listings for parts and connec-
tions.
Troubleshooting: Failure to raise or fold a platform
and platform drift (failure to hold the platform in a
raised or folded position) can simply be the result of
the backup pump release valve not being closed
tightly. Platform drift can also be the result of a loss
of pump prime or contamination around the ball
within the release valve seat. First, check to see
that the valve stem is closed tight. If this does not
solve the problem, proceed with the Priming and
Flushing Procedure - outlined at right.
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Lower platform fully
before priming or
flushing back-up
pump release valve.
Failure to do so may
result in serious
bodily injury and/or
property damage.
Priming and Flushing Procedure:
a. Lower platform fully.
b. Press the UP switch while simultaneously open-
ing the backup
pump release valve
(turn stem counter-
clockwise) until the
platform does not
raise.
c. Close the release
valve securely (turn
clockwise) and
check the backup
pump operation by
inserting the pump
handle and stroking.
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