SkyTrak 6042 Service Manual - Manual (Page 347)

8.115 Model 6042 Legacy Origin 7/02
Hydraulic System
e. Lift/Lower Cylinder Assembly
Note: Follow Section 8.13.3, “General Cylinder Assembly
Instructions.”
1. Install a new small oiled o-ring (Fig. 8-76, 12) into
the piston (8).
2. Install the capped T-seal (Fig. 8-76, 11) and both
precision wearbands (10) onto the piston (8).
Note: The T-seal actually consists of four components: a
wide, flexible inner band, the flexible T-seal band itself,
and two supportive split caps that mount on either side of
the “T” itself.
3. Install the precision wearbands (Fig. 8-76, 15) into
the forward end of the head gland (7). Install the
deep Z-seal with back-up (16) orienting the edge
(20). Install the sealed, outside diameter heavy-duty
rod wiper (18). The wiper lip (21) should be toward
the outer end of the head gland and the seal lips
toward the inner end of the head gland. Use tools
that will not damage the seals.
4. Install a new oiled o-ring (Fig. 8 -76, 13) and back-up
ring (14) onto the head gland (7).
5. Fasten the rear of the rod in a soft-jawed vise and
put a padded support below and near the threaded
end of the rod to help prevent damage to the rod.
6. Carefully slide the head gland (Fig. 8 -76, 7) onto the
rod (5).
7. Carefully slide the piston (Fig. 8-76, 8) onto the rod (5).
8. Apply Loctite Threadlocker #271 (red) to the threads
of the locknut (Fig. 8-76, 9). Thread the locknut onto
the rod (5). Torque to 1,750-2,000 lb-ft
(2.373-2.712 Nm).
IMPORTANT: Avoid using excess force when clamping
the cylinder in a vise. Apply only enough force to hold the
cylinder securely. Excessive force can damage the
cylinder tube (Fig. 8 -76, 2).
9. Secure the lift/lower cylinder in a soft-jawed vise or
other acceptable holding equipment if possible.
10. Lubricate the inside of the tube (Fig. 8 -76, 2) and
outside of the piston (8) and head gland (7) with
clean, filtered hydraulic oil.
11. Apply a compression sleeve or other suitable tool to
the head gland (Fig. 8-76, 7) and piston (8), in order
to compress the o-rings, back-up rings and seals
while inserting the assembled piston, rod and head
gland into the tube (2).
IMPORTANT: When sliding the rod (Fig. 8 -76, 5) and
piston assembly into the tube, prevent the threaded end
of the tube from damaging the piston (8). Keep the rod
centered within the tube to help prevent binding. Protect
the finish on the rod at all times. Damage to the surface
of the rod can cause seal failure.
12. Carefully insert the rod (Fig. 8-76, 5) with all
attachments straight into the tube (2).
13. Using a pin spanner wrench, thread the locking
collar (Fig. 8 -76, 6) into the tube (2). Torque the
locking collar to 300-400 lb-ft (407-542 Nm).
IMPORTANT: DO NOT tamper with or attempt to reset
the counterbalance valve cartridge (Fig. 8-76, 3). If
adjustment or replacement is necessary, replace a
counterbalance valve with a new part.
14. Lubricate the counterbalance valve (Fig. 8-76, 3)
and the pilot-operated check valve (4) with clean,
filtered hydraulic oil. Using new oiled o-rings, thread
the valves into tube (2). Torque to 30-35 lb-ft (41-47 Nm).
15. Test the cylinder at low operating pressure (100 psi
or 7 bar). Verify that the piston and the rod move
freely in both directions.
16. Increase the operating pressure to the maximum
amount for the cylinder (3,000 psi or 207 bar) and
again check for free movement in both directions.
17. Retract the rod fully into the tube, and cap and plug
the hydraulic hose ports.
f. Lift/Lower Cylinder Installation
1. Raise and support the boom to allow installation of
the lift/lower cylinder (Fig. 8-76, 1).
2. Attach a sling to the lift/lower cylinder and to a hoist
or an overhead crane. Safely and carefully, position
the lift/lower cylinder inside the frame aligning the
rod and base eyelets with mounting bosses of the
boom and frame.
3. Secure the cylinder with cylinder mount pins,
capscrews and nuts.
WARNING:
DO NOT get under a raised
boom unless the boom is blocked up. Always
block the boom before doing any servicing that
requires the boom to be up. Unexpected lowering
of the boom may cause death or serious injury.