Upright AB46 C, Service & Parts Manual

Page: 48 / 148

Section
3-30 AB46 Work Platform
Maintenance
3.21 Boom Extend Cylinder
REMOVAL
1. Lower boom completely. Extend boom until front
boom extend cylinder pin is accessable.
1. Use an overhead hoist or crane to support the rear
of the boom (Figure 3-30).
2. Remove rear boom pivot pin.
3. Remove clips which secure front boom extend
cylinder pin. Remove pin.
4. Mark and disconnect boom extend cylinder hoses
and immediately cap the openings to prevent
contamination.
5. Using overhead hoist, slightly raise rear of boom.
NOTE: This will extend master cylinder and allow
room to remove boom extend cylinder. It may be
necessary to remove a counterbalance valve to allow
master cylinder to expand.
6. Remove rear boom extend cylinder pin. Carefully
remove boom extend cylinder. Measure length of
expanded boom cylinder.
IMPORTANT: Boom extend cylinder must be ex-
panded to the same length when it is reinstalled.
DISASSEMBLY
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 be visible to the naked
eye.
1. Remove set screw and unscrew head from cylinder.
3. Carefully pull shaft assembly from cylinder.
4. Secure rod end and turn piston off of shaft.
NOTE: Piston is loctited (Loctite #277) onto rod.
4. Slide the head off of the rod.
5. Remove seal kit components (wipers, rod seals, o-
rings and backup rings) from head and piston.
6. 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.
7. Inspect cylinder parts for scratches, pits, or polish-
ing. Check seal groves and sealing surfaces.
Scratches or pits deep enough to catch the fingernail
are unacceptable, replace the cylinder. Polishing is
a sign of uneven loading. When this occurs, the
surface should be checked for roundness. Cylinders
not round within .007" should be replaced.
ASSEMBLY
NOTE: Torque all hardware to torques listed on page
3-32 unless otherwise specified.
1. Lubricate all components and seals with clean
hydraulic oil prior to assembly.
Note: To avoid cutting the seals, do not use sharp
edged tools during seal replacement. After installing
seals allow at least one hour for the seals to elasti-
cally restore to their original shape before assembling
cylinder.
2. Install new seal kit items to piston and head.
3. Lubricate rod wiper and seal with hydraulic oil and
slide head onto rod.
4. Clean threaded end of rod using loctite primer.
5. Using loctite #277, install piston onto rod.
6. Lubricate seals on piston and head with hydraulic
oil.
7. Carefully slide rod assembly into cylinder.
Figure 3-30: Removing Boom Extend Cylinder
3.21