SkyTrak 8042 Service Manual - Manual (Page 178)

Hydraulic System
8-34 6036, 6042, 8042, 10042, 10054
d. Cylinder Inspection
1. Inspect internal surfaces and all parts for wear,
damage, etc. If the inner surface of the cylinder
barrel does not display a smooth finish, or is scored
or damaged in any way, replace the barrel.
2. Remove light scratches on the piston, head gland,
rod or inner surface of the cylinder barrel with a 400-
600 grit emery cloth. Use the emery cloth in a rotary
motion to polish out and blend the scratch(es) into
the surrounding surface.
3. Check the piston rod assembly for run-out. If the rod
is bent, it must be replaced.
e. Cylinder Assembly Instructions
1. Use the proper tools for specific installation tasks.
Clean tools are required for installation.
2. Install new seals, back-up rings and o-rings on the
piston and new seals, back-up rings, o-rings and
bearing on the head gland.
Note: The extend/retract cylinder has a spacer that
MUST be installed over the rod
AFTER the head gland
and BEFORE the piston head.
3. Fasten the rod eye in a soft-jawed vise, and place a
padded support under and near the threaded end of
the rod to prevent any damage to the rod.
Note: Protect the finish on the cylinder rod at all times.
Damage to the surface of the rod can cause seal failure.
4. Lubricate and slide the head gland over the cylinder
rod. Install the piston head on to the end of the
cylinder rod. Loctite
® 243 TM and install the set screw
in the piston head. Refer to Section 8.8.4, “Cylinder
Torque Specifications” for torque specifications for
the piston head and the set screw.
Note: Avoid using excess force when clamping the
cylinder barrel in a vise. Apply only enough force to hold
the cylinder barrel securely. Excessive force can
damage the cylinder barrel.
5. Place the cylinder barrel in a soft-jawed vise or other
acceptable holding devise.
Note: When sliding the rod and piston assembly into the
cylinder barrel, prevent the threaded end of the cylinder
barrel from damaging the piston head. Keep the cylinder
rod centered within the barrel to prevent binding.
6. Carefully insert the cylinder rod assembly into the
cylinder barrel.
7. Screw the head gland into the cylinder barrel and
tighten with a spanner wrench. Refer to Section
8.8.4, “Cylinder Torque Specifications” for torque
specifications for the head gland.
8. If applicable, install new counter balance valve into
block on the cylinder barrel.
f. Cylinder Installation
1. Grease the bushings at the ends of the hydraulic
cylinder. Using an appropriate sling, lift the cylinder
into it’s mounting position.
2. Align cylinder bushing and install pin, lock bolt or
retaining clip.
3. Connect the hydraulic hoses in relation to the labels
or markings made during removal.
4. Before starting the machine, check fluid level of the
hydraulic fluid reservoir and if necessary fill to full
mark with Mobilfluid 424
® (ISO 46).
5. Start the machine and run at low idle for about one
minute. Slowly activate hydraulic cylinder function in
both directions allowing cylinder to fill with hydraulic
oil.
6. Inspect for leaks and check level of hydraulic fluid in
reservoir. Add hydraulic fluid if needed. Shut the
engine OFF.
7. Wipe up any hydraulic fluid spillage in, on, near and
around the machine, work area and tools.
8. Close and secure the rear door.
8.8.2 Cylinder Pressure Checking
Attach a 4000 psi (276 bar) gauge to the test port on the
hydraulic pump to check the system pressure. For more
information, refer to Section 8.3.1, “Pressure Checks and
Adjustments.”
Note: If a hydraulic cylinder pressure is greater than the
main control valve pressure, increase the main control
valve pressure by adjusting the main relief. Generally,
one half turn clockwise will be adequate to check an
individual circuit. Activate the circuit and if pressure is
obtained turn the main relief counter clockwise one half
turn. Re-check the main relief setting and adjust if
necessary.