Komatsu Excavator PC240

Warning: Only trained personnel should perform this procedure.

Sign off on the valve adjustment

Checking for leakage of oil from the PPC shuttle valve

Disconnect the hose between the PPC valve and the shuttle block at the block end

Install an adapter for measuring the oil pressure to the tip of the hose

Install blind plugs to the tip and shuttle block end

Operate the control lever and measure the output pressure

If the output pressure becomes normal, there is leakage from the PPC shuttle valve; if there is no change, the PPC valve is defective

Checking defective operation of PPC shuttle valve

Remove the oil pressure switch, fit adapter Cs

Install oil pressure gauge Ct (5.88 MPa (60 kg/cm2))

Any damages or deformations found?

Remedy: Replace EPC valve assembly if any damages or deformations are found

Sign off on the solenoid valve spring check

Enter the axial clearance of bearing 1

Does the clearance meet the standard?

If clearance exceeds limit, replace the bearing

Sign off on the swing circle check

If the load becomes larger, the engine speed will drop. Or if the engine speed remains normal, the work equipment speed will drop. In such cases, if the pump discharge pressure and LS differential pressure are normal, adjust the TVC valve as follows.

There are two sets, so adjust both the front and rear to the same angle.

1. Loosen locknut (3), and if the speed is slow, turn screw (4) to the left; if the engine speed drops, turn the screw to the right. If the screw is ·turned to the left, the pump absorption torque will be increased, and if it is turned to the right, the pump absorption torque will be reduced.

There is also a connection with the angle, so see Note below. The adjustment range for the screw is a maximum of 90° to both the left and right.

2. After completing the adjustment, tighten the locknut.

~ Locknut : 29.4 ± 4.9 Nm (3.0 ± 0.5 kgm)

Note: The screw is an eccentric cam, so if it is turned from position (a) in the graph, the stroke of the servo piston will move as shown in the graph. If it is turned one full turn, it will return to the original position, but the screw will become looser, so there will be play in the screw.

Therefore, turn the screw a maximum of 90° to the left and right from the position (a) set when the machine was shipped.;