Komatsu D61EX-24, D61PX-24 Dozer Service Manual

Table of Contents

• Index and foreword
• Specification
• Structure, function and maintenance standard
• Standard value table
• Testing and adjusting
• Troubleshooting
• Disassembly and assembly
• Maintenance Standard
• Appendix
• Circuit Diagrams
• Index

Proper service and repair are extremely important for safe machine operation. The service and repair techniques recommended by Komatsu and described in this manual are both effective and safe. Some of these techniques require the use of tools specially designed by Komatsu for the specific purpose.

Manual Extract

OPERATION OF EGR VALVE
1. The oil from the engine boost oil pump flows in port (C) of EGR valve. The control pressure from EPC valve solenoid enters port (E).
2. Spool (4) is moved to the right by the reaction force of spring (5), and valve (1) is closed by the reaction for spring (2). Accordingly, the exhaust gas from EGR cooler does not flow to the intake side.
3. To open valve (1), the control pressure from EPC valve enters port (E) first. The position of spool (4) is determined by the balance of the control pressure and spring (5).
4. Since the notch of power piston (3) opens, the oil from the engine boost oil pump flows through port (C) and pushes power piston (3) to the left.
5. The oil from the engine boost oil pump acts on power piston (3) and generates force (Fp).
6. When force (Fp) increases more than reaction force (Fs) of spring (2), EGR valve (1) opens and the exhaust gas flows to the intake side.
7. Reaction force (Fs) of spring (2) and force (Fp) of power piston are balanced since the engine controller controls the control pressure with EPC valve solenoid.
8. Since the servo mechanism is applied, external force applied to valve (1) does not act on spool (4) which is in contact with power piston (3).
9. EGR valve lift sensor senses the displacement of spool (4).