Komatsu PC80MR-3 Excavator Service Manual

Table of Contents

10. STRUCTURE AND FUNCTION…………………………………………………………………….. 10-1
20. TESTING AND ADJUSTING ………………………………………………………………………… 20-1
30. DISASSEMBLY AND ASSEMBLY ……………………………………………………………….. 30-1
90. OTHER………………………………………………………………………………………………………. 90-1

This Komatsu PC80MR-3 service manual has been prepared as an aid to improve the quality of repairs by giving the operator an accurate understanding of the product and by showing him the correct way to perform repairs and make judgements. Make sure you understand the contents of this manual and use it to full effect at every opportunity.
This service manual mainly contains the necessary technical information for operations performed in a service workshop.

The manual is divided into chapters on each main group of components; these chapters are further divided into the following sections.

STRUCTURE AND FUNCTION
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 AND ADJUSTMENTS
This sections 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 included in this section.

REMOVAL AND INSTALLATION FOR Komatsu PC80MR-3
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 traveling in a straight line
Function
• To compensate for any difference in the oil flow in the left and right travel circuits when traveling in a straight line, the junction circuit opens when the left and right travel spools are operated.
In this way, the flow of oil to the left and right travel motors is almost the same when traveling in a straight line, so there is no travel deviation.
• When steering the machine, the difference in the load pressure returns the reducing valve of the travel valve on the inside of the turn, so the junction circuit is closed and the machine can be steered.

Operation
• When left and right travel spools (1) are operated, the pump discharge flows from pump circuit PP and circuit PA to actuator circuit A.
• When traveling in a straight line, to make actuator circuit PA equal, left and right reducing valves (2) are pushed to the right (o) by the same amount, and notch a and the travel junction circuit are opened.
• In this way, the left and right travel actuator circuits are interconnected by the travel junction circuit, so if any difference occurs in the flow of oil to the left and right travel motors, the difference is compensated to prevent any deviation in travel.