Komatsu PC78MR-6 Excavator Service Manual

Table of Contents

01 GENERAL ………………………………………………………………………………………………….01-1
10 STRUCTURE AND FUNCTION,
MAINTENANCE STANDARD…………………………………………………………….10-1
20 TESTING AND ADJUSTING ……………………………………………………………..20-1
30 DISASSEMBLY AND ASSEMBLY ………………………………………………….30-1
90 OTHERS ……………………………………………………………………………………………………..90-1

GENERAL
This section lists the general machine dimensions, performance specifications, component weights, and fuel, coolant and lubricant specification charts.

STRUCTURE, FUNCTION AND MAINTENANCE STANDARD
This section explains the structure and function of each component. It serves not only to give an understanding of the structure, but also serves as reference material for troubleshooting.

TESTING, ADJUSTING AND TROUBLESHOOTING
This section explains checks to be made before and after performing repairs, as well as adjustments to be made at completion of the checks and repairs. Troubleshooting charts correlating Problems to Causes are also mention in this section.

DISASSEMBLY AND ASSEMBLY KOMATSU Excavator

This section explains the order to be followed when removing, installing, disassembling or assembling each component, as well as precautions to be taken for these operations.

When the load is increased, the engine speed may lower or the engine speed may be normal and working speed may be lower. If this trouble occurs and the pump discharge pressure and LS differential pressure are normal, adjust the pump PC valve according to the following procedure.

a Before loosening locknut, be sure to make match marks.
1. Loosen locknut (1) and adjust with adjustment screw (2).
a Since the PC valve is of eccentric type, in which direction the adjustment screw should be turned to increase the absorption torque is unknown.
Accordingly, monitor the engine speed when turning the adjustment screw.
2. After adjusting, tighten locknut (1).