Landoll 425B Series, Operator'S Manual

Page: 73 / 88

MAINTENANCE AND LUBRICATION
4-33
Dock Levelers
1. Perform the following service procedure on a yearly
basis:
a. Change oil with legs fully extended.
b. After oil change, operate the dock leveler at least
three full cycles (complete leg strokes) to bleed
air from system.
c. Fully extend legs. Clean extended legs. Coat
lightly with clean grease and grease alemite
fitting on each leg and check valve.
2. Check all hydraulic lines and fittings for leaks and
worn spots. Replace any defective lines and fittings.
3. Check for loose bolts and nuts.
Disassembly/Assembly Procedure
When disassembling and reassembling the leg, care
should be taken to keep all parts clean and to prevent
parts from being damaged. All seals should be coated
lightly with grease before reassembling the leg.
Leg
1. To remove leg from trailer, make sure no weight is
being supported by legs. Have legs slightly extended
from full retract position to relieve any internal
pressure in legs. Disconnect the hoses from the leg.
You may wish to mark which hose goes to what port.
Remove the leg from the trailer.
2. Remove the lock valve from the leg by screwing
counter clockwise
(See Figure 4-21.) If you need
only to repair the lock valve, it may be removed from
leg while still on trailer if you have a minimum of 2”
clearance above.
3. Remove o-rings and backup washers. Using a snap
ring pliers, remove snap ring. Loosen hex screw.
4. Lift well tube off lower leg assembly. Lift piston rod to
gain access to top of cylinder head.

CAUTION
5. Remove four hex screws. Lift cylinder head retainer.
A wire or rubber band may be used to hold cylinder
head retainer to sprocket near the top of piston rod
out of the way.
6. Using a small flat screwdriver, carefully remove spiral
retaining ring. Lift piston rod assembly out of cylinder
tube.
7. Using a large snap ring pliers, remove heavy duty
snap ring or remove the set screw. Remove the
piston, cylinder head, retaining ring, and cylinder
head retainer.
8. Remove all seals and wear rings. Clean all parts.
Inspect all bearing surfaces for scratches, nicks, or
other defects; replace if necessary. Replace all wear
rings, and lightly lubricate all seals before installing
on legs.
9. Carefully reassemble the leg in reverse order as
described above. Were applicable, torque piston to
40-50 ft.-lbs. Apply two drops of Loctite 277 or
equivalent to set screw and torque to 50 in./lbs.
Return leg to trailer and reconnect all hoses. Apply
grease to grease fittings and cycle legs fully several times
to bleed air from system. Check oil level.
Stabilizer Leg Check Valve
1. Remove lock valve as described in step 2 of “Leg”
on page 4-33.
2. Remove retaining plug (See Figure 4-22.)
3. Remove o-ring plug opposite retaining plug on
rectangular block.
4. Using a drift small enough to fit through the port
opened in the previous step, tap out the lock valve
cartridges.
5. Install new lock valve cartridges back to back (as
illustrated). Grease o-rings.
6. Install two new o-rings and two back-up washers on
retaining plug.
7. Thread retaining plug into body (tap gently to engage
threads). Torque plug to 15 ft.lbs.
8. Install new o-ring on plug, opposite retaining plug.
Thread plug into body. Torque to 70 in.lbs.
9. Replace spring and poppet. Replace the o-ring on
plug and reinstall.
10. Install new o-rings and back-up washers on top of
piston rod.
11. Thread lock valve on piston rod until firmly seated. If
the ports need to be relocated, loosen the screw at
the top of the well tube and turn lock valve clockwise
until ports are at the desired location. Retighten the
set screw.
While lifting piston rod, oil will squirt out of side
port at top of rod.