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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.
WARNING
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.
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.
WARNING
Troubleshooting:
Replacement of the
cylinder(s) is unneces-
sary unless platform
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
procedures will indicate
internal leakage.
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.
WARNING
Internal Leakage Test No. 1:
a. Place load (200 to 250 lbs.) on platform.
b. Raise loaded platform fully (floor level).
c. If a
continuous flow
of oil from a cylinder
(piston end) is visible in the return line during
the retract mode, replace the cylinder.
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 (floor level).
c. Allow the loaded platform to set in the raised
position overnight or longer.
d. If
any
measurable descent is visible, refer to
Section 5.40 of the Troubleshooting Diagno-
sis Chart for remedies.
Summary of Contents for CENTURY CL917IB
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