CYLINDERS
Cylinders
356
M8.0-1055-010
01 Rev. 6/08
Carriage Cylinder Reassembly
Care should be taken when inserting the cylinder cap,
to prevent threads and sharp edges from damaging
new seals and packings. Packings can also be dam-
aged by forcing air past seals.
When repacking the carriage cylinder, carefully bring
oil back into the system while the bleed screw is fully
open to allow air to burp.
After packings and seals are in place and the ram as-
sembly has been installed, reattach the cap.
Carriage Cylinder Bleeding and Flushing
Procedures
Avoid high pressure fluids - escaping fluid under pres-
sure can penetrate the skin causing serious injury. Re-
lieve pressure before disconnecting hydraulic lines.
Tighten all connections before applying pressure.
Keep hands and body away from pin holes which eject
fluids under high pressure. Use a piece of cardboard or
paper to search for leaks. Do not use your hand.
Any fluid injected into the skin under high pressure
should be considered as a serious medical emergency
despite an initial normal appearance of the skin. There
is a delayed onset of pain, and serious tissue damage
may occur. Medical attention should be sought imme-
diately by a specialist who has had experience with this
type of injury.
Carriage hydraulic circuits need to be flushed after re-
pair of carriage cylinders and bled of all air. Before
flushing and bleeding of system inspect all hydraulic
connections and verify that all filters are installed and
hydraulic fluid levels are adequate for test. Hydraulic
system must be pressurized during the flushing and
bleeding procedures.
Do not attempt to bleed a line by cracking a seal fitting.
This will result in damaging the seal which then must
be replaced to prevent hydraulic fluid leakage.
Carriage Cylinder Bleeding
1. Slowly elevate the empty carriage to approximately
1220 mm (48.0 in).
2. Slowly open each cylinder's bleed screws and
bleed air from cylinders until a solid stream of hy-
draulic fluid flows out of the cylinders.
3. Tighten bleed screw.
Carriage Cylinder Flushing
1. Slowly elevate the empty carriage to approximately
1220 mm (48.0 in).
After bleeding cylinders, actuate control valve to
raise carriage through free and stage lift and stop
to hold in position.
2. With carriage raised, examine cylinders for any
leaks.
3. Actuate control valve to lower carriage through
stage and free lift to examine operation and stag-
ing.
4. Raise and lower carriage rapidly for a minimum of
10 cycles to flush system.
Never stand or work under a suspended load.
Fully extend the mast with maximum rated load. The
load may not drift down more than 50 mm (2.0 in)
within five minutes.
Occasionally, a slight creep of the fork assembly may
occur due to internal cylinder seal leakage, but it can
also be caused by leakage in the check valves, control
valve, etc. To seat these valves properly when this oc-
curs, raise and lower the forks to flush out any foreign
material from the valve seat.
Crown 2007 PF15682-10 Rev. 6/08
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