SkyTrak 8042 Service Manual - Manual (Page 542)

8.127 Model 8042, 10042, 10054 Legacy Rev. 10/03
Hydraulic System
IMPORTANT: When sliding the rod (20) and piston
assembly into the tube, prevent the threaded end of the
tube from damaging the piston (3). 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.
14. Carefully insert the rod (20) with all attachments
straight into the tube (24).
15. Using a pin spanner wrench, thread the head gland
(9) into the tube (24). Torque the head gland to 300-
400 lb-ft (407-542 Nm).
16. Lubricate the counterbalance valve (25) and the
pilot-operated check valve (26) with clean, filtered
hydraulic oil. Using new oiled o-rings, thread the
counterbalance valve and the pilot-operated check
valve into the cylinder. Torque the valves to 150-160
lb-ft (203-217 Nm).
IMPORTANT: DO NOT tamper with or attempt to reset
the counterbalance valve cartridge. If adjustment or
replacement is necessary, replace a counterbalance
valve with a new part.
17. Test the cylinder at low operating pressure (100 psi
or 7 bar). Verify that the piston and the rod move
freely in both directions.
18. Increase the operating pressure to the maximum
amount for the cylinder 3000 psi (207 bar), and
again check for free movement in both directions.
19. Retract the rod fully into the tube, and cap and plug
the hydraulic hose ports.
f. Extend/Retract Cylinder Installation
1. Attach a suitable sling to an overhead crane or other
suitable device and to the extend/retract cylinder.
Make sure the device used can actually support the
cylinder. Place the extend/retract cylinder in position
guiding the rod end through the retainer on the outer
boom.
Note: Check the condition of the rubber bumper located
on the retainer. Replace if damaged. Refer to Section
3.3.3, “Outer Boom Removal.”
2. Coat the extend/retract cylinder base pin with anti-
seize compound and install the pin by tapping it in.
3. Secure the extend/retract cylinder base pin to the
boom with two 2" external retaining rings.
4. Guide the rod end into position aligning the eye with
the intermediate boom mounting holes. Coat the
extend/retract cylinder rod pin with anti-seize
compound and install the pin by tapping it in.
5. Secure the extend/retract cylinder rod pin to the
boom with two 2" external retaining rings.
6. Connect the extend/retract cylinder hydraulic hoses
in relation to the labels or markings made during
removal.
7. Start the engine and run at approximately one-third to
one-half throttle for about one minute without moving the
vehicle or operating any hydraulic functions.
8. Inspect for leaks and check the level of the hydraulic
fluid in the reservoir. Add hydraulic fluid to the
reservoir as needed. Shut the engine OFF.
9. Wipe up any hydraulic fluid spillage in, on, near and
around the vehicle, work area and tools.
10. Conduct a pressure check of the attachment tilt
cylinder hydraulic circuit and bleed the circuit as
outlined in the procedure that follows.
g. Extend/Retract Cylinder Pressure Checking and
Circuit Bleeding
1. Attach a 4000 psi (276 bar) gauge to the test fitting
on the main control valve to test the system
pressure. Pressure readings should be
3000 ±100
psi (207 ±7 bar). Refer to Section 8.7, “Hydraulic
System Testing.” To check the cylinder pressure,
consult the factory.
2. With no accessory installed on the quick attach, start
with the lift/lower and attachment tilt cylinders fully
retracted.
3. Fully extend the extend/retract cylinder. Hold the
joystick at full extend while fully raising the lift/lower
cylinder.
4. Fully retract the attachment tilt cylinder. Hold the
attachment tilt joystick at full retract while fully
retracting the lift/lower cylinder.
5. Repeat Steps 3 and 4 five times.
WARNING:
Avoid prolonged engine
operation in closed areas with inadequate
ventilation. Failure to properly ventilate exhaust
fumes can result in death or serious injury.
WARNING:
Escaping hydraulic fluid
under pressure can penetrate the skin, causing
death or serious injury.