16 819.4496
Service
Repairing the Air Valve
Tools Required
• Torque wrench
• Torx (T20) screwdriver or 7 mm socket wrench
• Needle-nose pliers
• O-ring pick
• Lithium base grease
NOTE: Air Valve Repair Kits 819.4274 (aluminum center
housing models) and 819.0249 (stainless steel
center housing models) are available. Refer to page
28. Parts included in the kit are marked with a
symbol, for example (4
†). Use all the parts in the kit
for the best results.
Disassembly
1. Relieve the pressure.
2. With a Torx (T20) screwdriver or 7 mm socket wrench,
remove the six screws (3), air valve cover (2), and
gasket (4). See F
IG. 7.
3. Move the valve carriage (5) to the center position and
pull it out of the cavity. Remove the valve block (7) and
o-ring (6) from the carriage. Using a needle-nose pliers,
pull the pilot block (18) straight up and out of the cavity.
See F
IG. 8.
4. Pull the two actuator pistons (11) out of the bearings
(12). Remove the u-cup packings (10) from the pistons.
Pull the pilot pins (16) out of the bearings (15). Remove
the o-rings (17) from the pilot pins. See F
IG. 9.
5. Inspect the valve plate (8) in place. If damaged, use a
Torx (T20) screwdriver or 7 mm socket wrench to
remove the three screws (3). Remove the valve plate (8)
and, on aluminum center housing models, remove the
seal (9). See F
IG. 10.
6. Inspect the bearings (12, 15) in place. See F
IG. 9. The
bearings are tapered and, if damaged, must be removed
from the outside. This requires disassembly of the fluid
section. See page 23.
7. Clean all parts and inspect for wear or damage. Replace
as needed. Reassemble as explained on page 17.
FIG. 7 ________________________
FIG. 8 ________________________
Warning
To reduce the risk of serious injury whenever you are
instructed to relieve pressure, always follow the Pressure
Relief Procedure on page 13.
3
2
4
2
04618B
Torque to 5.6–6.8 N•m.
2
18
5
1
7
6
5
2
3
3
11
16
04900B
See Detail at right.
Grease.
Grease lower face.
1
2
3
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