Upright LX31, Руководство по обслуживанию и запасным частям

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Section
4-24 LX 31/41 Work Platform
Maintenance
4.12 Lift Cylinder
(Figure 4-24)
REMOVAL
1. Raise and block the elevating assembly (see section 4.3).
2. Open emergency lowering valve to be sure all
pressure is out of the lift cylinder.
3. Remove and cap both hoses and fittings.
4. Remove the down valve and cable assembly.
5. Support the lift cylinder with a suitable lifting device
to prevent falling.
6. Remove the retaining bolts from the upper and lower
pivot pins.
7. Drive out the pivot pins, upper one first, then the
lower one.
8. Hoist the cylinder out of the elevating assembly from
the front. DO NOT sling the cylinder by the rod
end pivot, this will cause the cylinder to extend
when hoisted.
SEAL REPLACEMENT (Figure 4-24)
Note: Provide a clean work area for this operation,
and observe clean assembly practices. Seals and
hydraulic cylinder components are highly sensitive to
contamination that may not even be visible to the
naked eye.
1. Use a spanner wrench to unscrew the head from the
cylinder body tube.
2. Carefully slide the rod, piston, and head out of the
body tube and place on a clean surface.
4. Unscrew the locknut from the rod end.
5. Remove the piston from the rod.
6. Slide the head off of the rod.
7. Remove all of the old seals and wear rings, discard.
Do not remove the cast iron ring from the piston.
8. Thoroughly clean all parts with solvent. Rinse the
inside of the tube and allow to drain. A high pres-
sure rinse and wipe with a lint free rag is preferable.
9. Inspect the rod, head, piston, and tube for
scratches, pits, or polishing. Check seal groves and
sealing surfaces. Scratches or pits deep enough to
catch the fingernail are unacceptable, replace the
affected component. Polishing is a sign of uneven
loading, when this occurs, the surface should be
checked for roundness. Surfaces not round within
.007" should be replaced.
10. Inspect and clean the cushion orifice if any debris is
present.
11. Lubricate all components and seals with clean
hydraulic oil prior to assembly.
Note: During seal replacement steps, do not use
sharp edged tools to avoid cutting the seals. After
assembling all seals, allow at least one hour for the
seals to elastically restore to their original shape
before assembly. Refer to Figure 4-16 for component
identification and placement.
12. Separate the three components of the piston seal.
Stretch the rubber inner ring over the piston and
into the seal groove. Warm the teflon outer ring to
150
o
f using heated hydraulic fluid or water. Stretch
the teflon outer ring into the seal groove. Clean the
groove in the teflon ring and install the quad ring.
Verify that none of the rings have twisted.
13. Install the glass filled nylon wear rings into the outer
grooves in the piston.
14. Twist the u-cup seal into a 'C' shape and allow it to
snap into the groove in the head.
15. Use the above technique to install the wiper into the
head.
16. Install the static o-ring and the static backup ring into
the grove in the head. Verify that the backup ring is
closest to the threads.
17. Install the sealing o-ring between the threads and
the flange lip on the head, be careful not to damage
the o-ring on the threads.
18. Slide the head assembly onto the rod.
19. Install the static o-ring into the groove on the rod.
20. Install the piston onto the rod.
21. Install the locknut and torque to 1125 ft.-lbs.
22. Slide the piston, rod, and head into the tube. Be
careful not to damage the piston seal on the threads
during assembly. If necessary, use shimstock to
protect the piston seal when inserting.
23. Use a spanner wrench to tighten the head.
4.12