ME12002HYDRAULICSYSTEM

DisassemblingandAssembling theControlValve

GeneralInformation

1.Prepare fresh cleaning oil, hydraulic oil, grease, etc.

2.Prepare the hydraulic test equipment and tools (test for the relief characteristics, leakage, flow resistance, etc.). See “Tools” on page147.

3.All hydraulic pump components are manufactured with precision. Thoroughly clean the work area before disassembling and/or reassembling the pump.

4.Spread rubber sheet, cloth, paper, or similar material to cover the work area.

5.Be sure dust, sand, debris, etc. do not enter the pump control valve.

6.Remove the control valve from the excavator.

7.Attach caps and masking seals to all control valve ports.

8.Clean the outside of the control valve and be sure that the caps and masking seals are attached properly.

9.Carefully support the body section of the casing when carrying or transferring the control valve.

IMPORTANT:Do not lift the control valve by lifting the exposed spool, end cover section, etc.

10.Disassemble the pump on rubber sheet, cloth, paper, or similar material used to cover the work area. See step 4.

11.Do not disassemble any component that cannot be tested after re-assembly.

12.After re-assembly, test components for relief characteristics, leakage, flow resistance, etc.

Tools

Prepare the following tools before disassembling the control valve.

NameoftoolQuantitySize(mm)

Vice mounted on bench (soft jaws) 1 unit

Hexagon wrenchEach 1 piece8, 10 and 12 Socket wrenchEach 1 piece27 and 32 SpannerEach 1 piece27, 32, 41 Adhesive (Loctite #262) 1 piece

DisassemblingtheControlValve

PlaceControlValveinWorkArea

IMPORTANT:Disassemble the control valve in a clean and dry environment and do not damage the sealing flange faces.

DisassemblingofMainSpool(except straighttravel)

1.Using a 8 mm hexagon wrench, loosen hexagon socket head bolts and remove spring cover, and lock valve selector (for boom1).

IMPORTANT:When extracting each spool assembly from its casing, use care not to damage the casing.

2.Remove spool, springs, stopper, spring seats and spacer bolt in spool assembly condition from casing. See Figure 3-159.

3.Secure spool into a vice as shown. See Figure 3-160.

4.Using a 12 mm hexagon wrench, remove spacer bolt, disassemble springs, stopper and spring seats. See Figure 3-160.

DisassemblingtheCovers

1.Using a 8 mm hexagon wrench, loosen hexagon socket head bolts, remove spool cover, and lock valve selector (for arm1).

1.Using a 32 mm hexagon wrench, loosen plug, remove rod and springs. See Figure 3-161 and Figure