Part of the Doosan Repair Manuals.
Wrench on a Doosan DX420LC? This 862-page Doosan DX420LC Shop Manual PDF (OEM #K1009096AE) covers the whole track excavator family: DX300LC, 340LC, 350LC, 420LC, and 480LC. Inside: the full electrical schematic, hydraulic schematics for the A8VO200 main pump circuit, a dedicated troubleshooting, testing, and pressure-adjustment section, plus page after page of standard torque tables. You get teardown and reassembly steps for the swing motor, travel motor with planetary gearbox, main control valve, cylinders, and the 360-degree center joint. Torque the fuel tank mounting nut to 27 kg-m (200 ft lb), and set lower roller shaft-to-bushing clearance between 0.300 and 0.405 mm. Your excavator is down and the clock is running. Bookmarked with a real text layer; jump straight to any valve section or hunt a spec by keyword, right from your phone in the pit.
What's Inside This Doosan DX420LC Manual
| System | Pages | Key Topics |
|---|---|---|
| Dx420Lc | 1-4 | - |
| Safety | 7-50 | Track Excavator Safety |
| Specifications | 51-78 | Specification for DX420LC |
| General Maintenance | 79-116 | General Maintenance Procedures, Standard Torques |
| Upper Structure | 117-224 | Cabin, Counterweight, Fuel Tank, Fuel Transfer Pump (Opt), Swing Bearing, Swing Reduction Gear |
| Lower Structure and Chassis | 225-266 | Track Assembly |
| Engine and Drive Train | 267-276 | Drive Coupling (Main Pump) |
| Hydraulic System Troubleshooting, Testing and Adjustment | 277-312 | Hydraulic Schematic, Operation of Working Components, Pilot Pressure, Power Mode Valve, Pressure Up Valve |
| Accumulator | 313-320 | Gas-Charged Storage, Diaphragm, Precharge Pressure, P1 Rated Pressure |
| Center Joint (Swivel) | 321-334 | Hydraulic Oil Flow, 360-Degree Rotation, Disassembly, Reassembly |
| Cylinders | 335-364 | Boom Cylinder, Arm Cylinder, Piston Nut, Slipper Seal, Cylinder Performance Tests |
| Swing Motor | 365-400 | Rotary Power, Relief Valve, Parking Brake, Makeup Check Valve, Time Delay Valve |
| Travel Motor (with Gearbox) | 401-456 | Planetary Gearbox, Brake Valve, Capacity Control, Overload Valve, Disassembly and Assembly |
| Main Pump | 457-514 | A8VO200LA1KH1/63, Control Module, Rotary Groups, Drive Shaft Sealing, Gear Pump Sealing |
| Hydraulic Components and Valves (Gear Pump to Breaker EPPR Valve) | 515-696 | Gear Pump, Main Control Valve, Remote Control Valve, Travel Control Valve, Fan Motor, Solenoid Valve Assembly, Breaker EPPR Valve |
| Electrical System | 704-832 | Electrical Schematic DX420LC |
| Attachments | 833-862 | Boom and Arm, Bucket |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Bolt torque for fuel filter head plug | 27 kg•m (200 ft lb) | p. 152 |
| Maximum Output Torque (DX420LC) | 2,360 kg•m (17,070 ft lb) | p. 182 |
| Maximum Output Torque (DX340LC / DX350LC) | 2,100 kg•m (15,189 ft lb) | p. 182 |
| Lower Roller - Clearance between shaft and bushing | 0.300 - 0.405 mm | p. 238 |
| Lower Roller - Interference between roller and bushing | 0.067 - 0.132 mm | p. 238 |
| Hydraulic reservoir return line and pilot circuit filter rating | 10 micron | p. 286 |
| Reservoir intake strainer micron rating | 177 micron | p. 286 |
| Adjustment screw (2) Pi-Q control valve compensating control pressure change | -0.7 kg/cm2 per 1/2 turn | p. 301 |
| Adjustment screw (3) Pd-Q curve shift/input horsepower change | +33 kg/cm2 per 1/2 turn | p. 301 |
| Nominal sectional area of wire core less insulator | 0.85 mm2 | p. 106 |
| Filter cleaning interval | 500 hours | p. 787 |
| Fuel Tank Capacity | 550 liters | p. 66 |
Doosan DX420LC Common Problems This Manual Covers
Doosan DX420LC hydraulic functions slow and weak under load, pump whining, hydraulic oil running hot
Check hydraulic oil level first; the reservoir holds 265 liters and a low level lets the pump pull air and cavitate. Test main relief pressure against the 320 kg/cm2 spec on page 72 using the procedures starting on page 279. Cut open the 10 micron return filter and inspect for metal before condemning the pump.
Manual Section: Hydraulic System Troubleshooting, Testing and Adjustment p. 279Engine cranks slowly or will not start, intermittent no-crank in cold weather
Test battery voltage under load before touching the starter. Clean and tighten both battery cables and the frame ground strap; corroded grounds cause most intermittent no-crank complaints. Trace the start circuit on the wiring diagram on page 832, and replace any damaged wire with core sectional area of at least 0.85 mm2.
Manual Section: Electrical System p. 832Travel is jerky and loses power on one side, grinding noise from final drive gearbox
Drain the travel gearbox oil and check it for metal flake; glitter in the drain pan means gear or bearing wear inside. Inspect the planetary gearbox and brake valve following the travel motor procedures starting on page 401. When reassembling, torque the M10 x 25 socket head cap screws to 8 kg•m (78.5 Nm) per page 444.
Manual Section: Travel Motor (with Gearbox) p. 401Tracks keep running loose, derail on tight turns, track rollers and idlers wearing out fast
Adjust track tension first; a loose chain derails on turns and hammers the sprockets. Measure lower roller shaft-to-bushing clearance against the 0.300 to 0.405 mm limit on page 238 and replace any roller past it. Refill each rebuilt lower roller with 450 cc (15.2 oz) of new engine oil as shown on page 251.
Manual Section: Lower Structure and Chassis p. 225Cab air conditioner blows warm, compressor cycles on and off, weak airflow at vents
Check refrigerant pressure with a gauge set before swapping parts; low charge and air in the system both cause weak cooling. Recover, pull vacuum, and recharge with exactly 800 grams of R134a per page 808. Clean the cab air filters and keep them on the 500 hour cleaning interval listed on page 787.
Manual Section: Air Conditioner Troubleshooting p. 808Frequently Asked Questions
How do I reset the service hours for the filter and oil information?
After changing the filter and oil, you can reset the operating hours using the 'Filter/Oil Info' mode in the main menu. This allows you to easily track the time remaining until the next service interval. p. 738
What is the procedure for clearing the failure log in the special menu?
To delete the memorized record of past failures, select the 'Delete Fail Log' mode in the special menu. When the 'YES' button is pressed, the record will be deleted, and a deletion signal will be displayed for 3 seconds. p. 747
What is the tightening torque for the M12 hex bolts on the cabin floor?
The mounting nut torque for the M12 hex bolts on the cabin floor is 11 kg•m (108 N•m, 80 lbf ft). p. 128
What is the fuel tank capacity for the DX420LC?
The fuel tank capacity for the DX420LC is 550 liters (145 U.S. gal). p. 147
What is the correct tightening torque for the M16x40 bolts on the swing reduction gear?
The tightening torque for the M16x40 bolts on the swing reduction gear is 2,700 kgf•cm. p. 201
What exactly do I receive with this Doosan DX420LC Shop Manual?
Instant PDF download. You get the full 862-page searchable Shop Manual immediately after payment. Open it on your laptop, tablet, or phone right in the shop.
Are there any print restrictions on this Doosan DX420LC manual?
Print away. There is no DRM and no page limit. Many buyers print one chapter at a time and leave the rest on a tablet.
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