JLG GRADALL 522, Owner'S/Operator'S Manual

Page: 68 / 288

OPEN CENTER HYDRAULIC BRAKE VALVE
SLIDING PISTON DESIGN
(Refer to Figure 12)
Remove boot (item 1) and
pressure regulating spring
assembly (item 2).
CAUTION: Pressure regulating
spring assembly has
been set at the fac-
tory and should
never be disas-
sembled.
Separate end cap (item 20) from
housing (item 3).
CAUTION: Care must be taken
as end cap is under
tension of spring
(item 18).
Remove gasket (item 6).
Remove piston & poppet
assembly (item 15), spring (item
18) and residual valve (item 19)
from end cap (item 20).
Inspection
Clean and inspect all component
parts for scratches, cracks or wear.
Replace any par ts that are
excessively worn or damaged.
CAUTION:
Disassembly
1.
2.
3.
4.
5.
6.
7.
or broken, the entire
assembly must be
replaced. These parts
are select-fitted and are
not interchangeable or
replaceable with
service items.
Install new cup (item 12) and new
piston ring (item 13) on sleeve &
piston assembly (item 14).
CAUTION:
Assembly
Lips on cup (item
12) should be away
from end of sleeve
(item 14).
Insert spool (item 10) and push
rod (item 8) into sleeve & piston
assembly (item 14). Secure with
retaining ring (item 7).
Carefully install sleeve & piston
assembly (item 14) into housing
(item 3).
Install lock washers (items 21)
and bolts (items 22). Torque 16
to 18 ft. lbs.
Install pressure regulating spring
assembly (item 2) on push rod
(item 8). Install new boot (item 1).
SEE BLEEDING SECTION FOR
COMPLETE BLEEDING
INSTRUCTIONS
PARTS LIST
ITEM DESCRIPTION
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
BOOT
PRESSURE REGULATING
SPRING ASSEMBLY
HOUSING
O-RING
CAP SCREW
GASKET
RETAINING RING
PUSH ROD
CUP
SPOOL
SPRING
CUP
PISTON RING
SLEEVE & PISTON
ASSEMBLY
PISTON & POPPET
ASSEMBLY
O-RING
RING SEAL
SPRING
RESIDUAL VALVE
END CAP
LOCKWASHERS
BOLTS
•
•
•
•
•
•
•
•
•
•
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Remove cap screw (item 5) from
under side of housing (item 3).
Remove o-ring (item 4) from cap
screw.
Remove sleeve & piston
assembly (item 14) from housing
(item 3). Remove cup (item 12)
and piston ring (item 13) from
sleeve & piston assembly (item
14).
Remove retaining ring (item 7)
carefully with a small flat tool. Do
not scratch bore of sleeve & piston
assembly (item 14).
Remove push rod (item 8), spool
(item 10) and spring (item 11) from
sleeve & piston assembly (item
14). Remove cup (item 9) from
spool (item 10).
Place new gasket (item 6) on
mounting face of end cap (item
20) and assembly, with its
components, to housing (item 3).
Extreme care must be
taken so as not to
scratch ring seal (item
17) when installing
piston & poppet
assembly (item 15) in
end cap (item 20). CAUTION:
If spool (item 10),
sleeve (item 14) or
bore of housing (item
3) are in any way
damaged, scratched
Install new cup (item 9) on spool
(item 10).
Lips on cup (item 9)
should be away from
end of spool (item
10).
CAUTION:
Install new o-ring (item 4) on cap
screw (item 5) and install in
housing (item 3).
Install new o-ring (item 16) and
new ring seal (item 17) on new
piston & poppet assembly (item
15).
Place residual valve (item 19),
spring (item 18) and piston &
poppet assembly (item 15) in end
cap (item 20).
NOTE: Residual valve must be
checked for proper
seating in end cap.
Make sure that
groove on sleeve
will engage screw
(item 5).
CAUTION:
(12)
Courtesy of Crane.Market