Hitachi FD2 1590 Service, Repairing the Air Valve, Tool Required, Disassembly, Reassembly

Service

Service

Repairing the Air Valve

Tool Required

•Torque wrench

•Torx (T20) screwdriver or 7 mm (9/32 in.) socket wrench

•Needle-nose pliers

•O-ring pick

•Lithium base grease

Air Valve Repair Kit 255061 is available. 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

To reduce the risk of serious injury, whenever you are instructed to relieve pressure, always follow the Pres- sure Relief Procedure on page 11.

1.Relieve the pressure.

2.With a Torx (T20) screwdriver or 7 mm (9/32 in.) socket wrench, remove the six screws (3), air valve cover (2), and gasket (4). See FIG. 5.

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 nee- dle-nose pliers, pull the pilot block (18) straight up and out of the cavity. See FIG. 6.

4.Pull the two actuator pistons (11) out of the bearings

(12). Remove the u-cup packings (10) from the pis- tons. Pull the pilot pins (16) out of the bearings (15). Remove the o-rings (17) from the pilot pins. See FIG. 7.

5.Inspect the valve plate (8) in place. If damaged, use a Torx (T20) screwdriver or 7 mm (9/32 in.) socket wrench to remove the three screws (3). Remove the valve plate (8). See FIG. 8.

6.Inspect the bearings (12, 15) in place. See FIG. 7. The bearings are tapered and, if damaged, must be removed from the outside. This requires disassem- bly of the fluid section. See page 24.

7.Clean all parts and inspect for wear or damage. Replace as needed. Reassemble.

Reassembly

1.If you replaced the bearings (12, 15), reinstall as explained on page 24. Reassemble the fluid section.

2.Install the valve plate (8) in the cavity, seal down. Install the three screws (3), using a Torx (T20) screwdriver or 7 mm (9/32 in.) socket wrench. Tighten until the screws bottom out on the housing. See FIG. 8.

3.Install an o-ring (17†) on each pilot pin (16). Grease the pins and o-rings. Insert the pins into the bear- ings (15), narrow end first. See FIG. 7.

4.Install a u-cup packing (10†) on each actuator pis- ton (11), so the lips of the packings face the narrow end of the pistons. See FIG. 7.

5.Lubricate the u-cup packings (10†) and actuator pis- tons (11). Insert the actuator pistons in the bearings (12), wide end first. Leave the narrow end of the pis- tons exposed. See FIG. 7.

6.Grease the lower face of the pilot block (18†) and install so its tabs snap into the grooves on the ends of the pilot pins (16). See FIG. 6.

7.Grease the o-ring (6†) and install it in the valve block (7†). Push the block onto the valve carriage

(5). Grease the lower face of the valve block. See FIG. 6.

8.Install the valve carriage (5) so its tabs slip into the grooves on the narrow end of the actuator pistons (11). See FIG. 6.

9.Align the valve gasket (4†) and cover (2) with the six holes in the center housing (1). Secure with six screws (3†), using a Torx (T20) screwdriver or 7 mm (9/32 in.) socket wrench. Torque to 52-60 in-lb (5.6-6.8 N•m). See FIG. 5.

16 311879F