Doosan DX420LC-3 Excavator Service Manual

Table of Contents

Safety
Track Excavator Maintenance Safety …………………………………………… SP002322
Specifications
Specification for DX420LC-3 ………………………………………………………. SP002670
General Maintenance
General Maintenance Instructions……………………………………………….. SP002454
Standard Torques……………………………………………………………………… SP002404
Upper Structure
Cabin ………………………………………………………………………………………. SP002324
Counterweight…………………………………………………………………………… SP002697
Fuel Tank…………………………………………………………………………………. SP002699
Fuel Transfer Pump (Option) ………………………………………………………. SP002560
Swing Bearing…………………………………………………………………………… SP002329
Lower Structure and Chassis
Track Assembly ………………………………………………………………………… SP002561
Engine and Drivetrain
Engine……………………………………………………………………………………… SP002654
Engine Coolant Heater (Option) ………………………………………………….. SP002328
Drive Coupling (Main Pump)……………………………………………………….. SP002562
Hydraulics
Hydraulic System Troubleshooting, Testing and Adjustment …………… SP002655
Accumulator……………………………………………………………………………… SP002455
Center Joint (Swivel)………………………………………………………………….. SP002545
Cylinders………………………………………………………………………………….. SP002769
Swing Device……………………………………………………………………………. SP002653
Travel Device……………………………………………………………………………. SP002609
Main Pump……………………………………………………………………………….. SP002567
Gear Pump ………………………………………………………………………………. SP002568
Fan Motor for Oil Cooler …………………………………………………………….. SP002576
Fan Motor for Radiator……………………………………………………………….. SP002577
Fan Pump ………………………………………………………………………………… SP002553
Main Control Valve ……………………………………………………………………. SP002656
Remote Control Valve (Work Lever / Joystick) ………………………………. SP002578
Travel Control Valve (with Damper)……………………………………………… SP002381
Solenoid Valve Assembly …………………………………………………………… SP002406
Breaker EPPR Valve (Option) …………………………………………………….. SP002458
Hydraulic Schematic………………………………………………………………….. SP002671
Electrical System
Electrical System ………………………………………………………………………. SP002571
Electrical Schematic ………………………………………………………………….. SP002572
Attachments
Boom and Arm………………………………………………………………………….. SP002669
Bucket……………………………………………………………………………………… SP002421

CMP Sensor
The CMP sensor is installed on the supply pump portion, and a CMP signal is generated every time the cam portion of the camshaft inside the supply pump passes the sensor.The ECM determines the cylinder and specifies the crank angle based on the CKP signal and the CMP signal input from the CMP sensor, and uses the information for the fuel injection control and calculation of the engine rpm.
While this control is usually performed using the CKP signal, the CMP signal is used instead when the CKP sensor is faulty.

Oil Pressure Sensor
The oil pressure sensor is installed near the starter motor of the cylinder block, it detects the pressure of the engine oil to convert it into a voltage signal, then sends it to the ECM.
The voltage becomes higher when the pressure is higher, and it becomes lower when the pressure is lower.

How to Use The Guide Manual:

This manual provides information for servicing the Excavator. All service procedures are broken down into detailed steps, listed in their recommended sequence. The manual uses both photographs and drawings to help locate and itemize components. The table of Contents on the preceding pages is your best tool for finding the service procedure you need. Be certain to observe all Safety information included in these pages.

A schematic of each of the major engine systems is provided at the beginning of the section of the manual devoted to troubleshooting and repairing that particular system.

Basic safety precautions are list in the Safety section of the Service Manual. Additional safety precautions are list in the Safety section of the owner/operation/maintenance publication. Specific safety warnings for all these publications are provided in the description of operations where hazards exist. WARNING labels have also been put on the product to provide instructions and to identify specific hazards.