Lull 6K Service Manual - Manual (Page 598)

Brakes
9-24 Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K
3. While watching test gauge, press brake pedal numerous times until
pressure gauge reads 0 psi. At this point, the “free-floating” piston will
be bottomed at the hydraulic end cap. Remove test gauge and cap
diagnostic port.
4. To release pre-charge pressure in accumulator, perform the following
steps (see Fig. 9-2 on page 9-2):
a. Remove two (2) capscrews (Item 1) and gas valve guard (Item 2).
b. Remove gas valve cap (Item 3) from gas valve (Item 9).
c. Back “T” handle (Item 8) on accumulator test gauge (Item 5) all the
way out (counter clockwise). The bleed valve (Item 4) should be
closed (turned in).
d. Mount test gauge on accumulator gas valve (Item 9). Be sure of an
air-tight connection when mounting the gauge.
e. Turn “T” handle all the way down. This will depress (open) the core
in gas valve.
f. Slowly open bleed valve to release gas pressure.
g. Wait until all gas pre-charge is released from accumulator
(pressure gauge reads 0 psi). Remove pressure gauge and
temporarily reinstall gas valve cap (Item 3).
CAUTION: Do not release pre-charge by depressing valve core with a
foreign object. High pressure may rupture rubber valve seat.
5. To avoid possible contamination of hydraulic system, clean swivel nut
on hydraulic hose (Item 10) and elbow (Item 11) on bottom of
accumulator (Item 5) with solvent.
6. Slowly loosen and remove hydraulic hose connected to elbow. Drain
remaining oil into appropriate container. Cap elbow and hydraulic hose
end.
7. Loosen hex nut (Item 7), lockwasher (Item 8), and capscrew (Item 9)
securing accumulator to mounting bracket (Item 6) enough so
accumulator may be removed.
CAUTION: Do not completely remove hex nut, lockwasher, and capscrew.
Care must be taken to avoid personal and/or equipment
damage when accumulator is being removed.
8. Loosen and remove three (3) capscrews (Item 13) and lockwashers
(Item 12) securing accumulator to valve plate.
9. Carefully remove the accumulator and take it to an appropriate place
for further disassembly and cleaning.
Note: Threaded holes in the accumulator end cap may be used as a means of
attachment for lifting. A sling around the body may also be used.