JLG GRADALL 522D Owner's/Operator's Manual page 66

OPEN CENTER HYDRAULIC BRAKE VALVE
RING SEAL DESIGN
(Refer to Figure 11)
Disassembly
1.
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.
2.
Separate end cap (item 21) from
housing (item 11).
CAUTION: Care must be taken
as end cap is under
tension of spring
(item 20).
Remove gasket (item 14).
3.
Remove piston & poppet
assembly (item 17) and spring
(item 20) from end cap (item 22).
If you have model
CAUTION:
06-460-566, you will
also have to remove
residual valve (item
21).
4.
Remove cap screw (item 13) from
under side of housing (item 11).
Remove o-ring (item 12) from cap
screw.
5.
Remove retaining ring (item 8)
from housing (item 11).
6.
Remove sleeve (item 10) by pulling
on push rod (item 4). Remove cup
(item 9) from sleeve.
7.
Remove piston (item 16) from
housing (item 11). Remove piston
ring (item 15) from piston.
8.
Remove retaining ring (item 3)
carefully with a small flat tool. Do
not scratch bore of sleeve (item
10).
9.
Remove push rod (item 4), spool
(item 6) and spring (item 7) from
sleeve (item 10). Remove cup
(item 5) from spool (item 6).
Inspection
Clean and inspect all component
parts for scratches, cracks or wear.
Replace any par ts that are
excessively worn or damaged.
(10)
CAUTION: If spool (item 6), sleeve
(item 10) or bore of
housing (item 11) are in
any way damaged,
scratched or broken,
the entire assembly
must be replaced.
These parts are select-
fitted and are not
interchangeable or
replaceable
service items.
Assembly
1.
Install new cup (item 9) on sleeve
(item 10) and new cup (item 5) on
spool (item 6).
Lips on cups (items
CAUTION:
5 & 9) should be
away from ends of
spool (item 6) and
sleeve (item 10).
2.
Place spring (item 7) in sleeve
(item 10).
3.
Install spool (item 6) in sleeve
(item 10). Note direction of spool.
4.
Install push rod (item 4) in sleeve
(item 10) and secure it with
retaining ring (item 3).
5.
Install new o-ring (item 12) on cap
screw (item 13) and install in
housing (item 11).
6.
Carefully install sleeve (item 10)
into housing (item 11).
CAUTION: Make sure
groove on sleeve
will engage cap
screw (item 13)
Install retaining ring (item 8).
Install piston ring (item 15) on
7.
piston (item 16) and install in
housing (item 11).
Install new o-ring (item 18) and
8.
new ring seal (item 19) on new
piston & poppet assembly (item
17).
Install spring (item 20) and piston
9.
& poppet assembly (item 17) in
end cap (item 22).
NOTE: If you have model 06-460-
566, you will have to install
new residual valve (item
21). You must also check
residual valve for proper
seating in end cap.
CAUTION: Extreme care must be
taken so as not to
scratch teflon seal
(item
installing piston &
poppet assembly (item
17) in end cap (item 22).
with 10. Place new gasket (item 14) on
mounting face of end cap (item
22) and assemble, with its
components, to housing (item 11).
11.
Install lock washers (item 23) and
bolts (item 24). Torque 16 to 18
ft. lbs.
12.
Install pressure regulating spring
assembly (item 2) on push rod
(item 4). Install new boot (item 1).
SEE BLEEDING SECTION FOR
COMPLETE BLEEDING
INSTRUCTIONS
PARTS LIST
ITEM DESCRIPTION
1 • BOOT
*
2
PRESSURE REGULATING
SPRING ASSEMBLY
3 RETAINING RING
4
PUSH ROD
5 • CUP
*
6 SPOOL
that
7
SPRING
8 RETAINING RING
9 •
CUP
*
10
SLEEVE
11 HOUSING
12
• O-RING
*
13
CAP SCREW
14 GASKET
•
*
15
PISTON RING
*
16 PISTON
17
PISTON & POPPET
•
*
ASSEMBLY
•
18 O-RING
*
19 •
RING SEAL
*
20
SPRING
21 RESIDUAL VALVE
*
22 END CAP
LOCKWASHERS
23
BOLTS
24
19) when
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