Snorkel A38E, Parts And Service Manual

Page: 129 / 155

Maintenance
Process
Section
4-25
4.18
4.18 Master Levelling Cylinder
(Figure 4-20)
REMOVAL
1. Ensure that the A38E is on firm level ground,
the Elevating Assembly is completely stowed,
the Keyswitch is to the ‘OFF’ position and the
Emergency Stop Button is pressed.
2. Provide a suitable container to collect the
hydraulic fluid, then disconnect the hydraulic
hoses. Immediately plug hoses to prevent
foreign material from entering.
3. Remove securing bolts and pin lock plates from
the rod end cylinder pin. Remove the circlip
from the barrel end of the cylinder
4. Support barrel end of cylinder and remove rod
end pivot pin. Move cylinder backwards and
allow to hang freely.
5. Support the cylinder so that the barrel end
cylinder pin can be removed, then remove the
cylinder from the machine.
6. Move the cylinder to a prepared work area. It is
important that clean assembly practices are
observed as seals and other hydraulic cylinder
components are highly sensitive to
contamination.
DISASSEMBLY (Refer to Figure 4-16)
1. Unscrew the headcap and withdraw the rod and
piston assembly from the barrel tube.
2. Unscrew the piston nut and remove piston and
headcap from the cylinder rod.
3. Remove the piston static O-ring from the
cylinder rod.
4. Remove the piston seal from the piston.
5. Remove the rod seal, rod wiper and static seal
from the headcap.
6. Care should be taken to save the O-ring and all
other seals for reassembly, if they have been
deemed serviceable following the cleaning and
inspection phase of maintenance.
CLEANING AND INSPECTION
1. Clean all metal parts in solvent and blow dry
with filtered compressed air.
2. Check all threaded parts for stripped or
damaged threads.
3. Check the bearing surfaces inside of the
headcap, outer edge surface of the piston,
inside of the cylinder barrel and the shaft for
signs of scoring, pits, excessive wear or
polishing. Scratches or pits deep enough to
catch a fingernail are unacceptable. Polishing is
a sign of uneven loading and if sufficiently
polished the affected parts should be replaced.
4. Replace any parts or seals found to be
unserviceable.
REASSEMBLY/SEAL REPLACEMENT
1. Lubricate and install new rod seal, rod wiper
and static seal on the headcap.
NOTE: Multi-purpose lubricant should be used.
2. Install a new piston seal on the piston.
3. Install the headcap on the cylinder from the
piston end.
4. Install the piston, piston nut and a new piston
static O-ring on the cylinder rod. Screw nut to
end of thread and secure with circlip.
5. Lubricate the piston seal and install the piston
and rod assembly in the barrel tube.
6. Thread headcap onto barrel tube and hand
tighten, then turn 1/4 turn further.
7. Install the Master Cylinders Overcentre Valves.
INSTALLATION
NOTE: Before installing the Master Cylinder check
cylinder pins and bearings for wear and replace if
necessary.
1.
Install barrel end bearing (if removed).
2. Lift the barrel end of the cylinder into place and
push the barrel end pivot pin in until the circlip
grooves are exposed, then attach the circlip.
NOTE: Take care in aligning the holes so that
the pin can be pushed in by hand. If holes are
not properly aligned and the pin is forced in, the
bearings will be damaged.
3. Align pin lock plate on cylinder pin with hole in
the 2
nd Post and push the cylinder pin
completely in and fix pin lock plate with bolt.
4. Install rod end bearings (if removed).
5. Lift rod end of cylinder into place and insert the
rod end pivot pin until the circlip grooves are
exposed, then attach the circlip. Install the pin
lock plate.
6. Fix pin lock plate with bolt.
7. Test with weight at rated platform load to check
system operation.
Note: During seal replacement do not use sharp
edged tools to avoid cutting the seals, and allow
at least one hour for the seals to elastically
restore to their original shape before assembly.