UPPERSTRUCTURE / Pilot Valve Assemble Right and Left Pilot Valves IMPORTANT: The pilot valve is susceptible to contamination. Keep the parts clean when assembling. 1. Install O-ring (20) to plug (21). Install plug (21) and retaining ring (22) to casing (18). IMPORTANT: Refer to the table in left in order to assemble them correctly. 4. Install spacers (1) (4 used), shim (2) and balance springs (3, 4) (2 used for each) to spools (19) (4 used). Install return springs (5, 6) (2 used for each) to casing (18). 5. Install spring guides (7) (4 used) onto return springs (5, 6) (2 used for each) with the protrusion facing upward. 6.
Install special tool (ST 4146) to the pusher (9, 10) hole on casing (18). Push special tool (ST 4146) and compress the spring. Tighten special tool (ST 4146) by using the bolts (M14, Pitch 2.0 mm). NOTE: Table below shows the relations between each port and the components. Do not confuse them when assembling. : 12 mm ST 4146 ST 4144 2. Check the port number. Insert same spools (19) (4 used) before disassembling. Slowly rotate and install the thinner end of spool (19) to the port hole on casing (18). W178-02-07-049 7. Install retaining ring (8) to ring holder (ST 4144). ST 4145 NOTE: Spool (19) has been selected to match the port hole.
Spool (19) and casing (18) must be replaced as an assembly. 3. Install special tool (ST 4145) to the port hole on casing (18) in order not to lower spool (19) when the spring is compressed. : 6 mm W2-7-23 Port No. Spool (19) Shim (2) Pushers A, B (9, 10) 1 Same to the former one Same to the former one Outer grooves (1 used) 2 Outer grooves (2 used) 3 Outer grooves (1 used) 4 Outer grooves (2 used) Port No. Return Springs (5, 6) Balance Springs A, B (3, 4) 1 Short Short 2 Long Long 3 Short Short 4 Long Long