Komatsu WA420-3 Wheel Loader Shop Manual PDF – Serial 50001 and Up

Description

File Details

• Manual type: Shop Manual
• Brand: Komatsu
• Model: WA420-3 Wheel Loader
• Serial number: 50001 and up
• Engine: S6D108 / SA6D108
• Language: English
• Page count: 828
• File format: PDF

Chapters Covered

• 01 GENERAL
• 10 STRUCTURE AND FUNCTION
• 20 TESTING AND ADJUSTING
• 30 DISASSEMBLY AND ASSEMBLY
• 40 MAINTENANCE STANDARD

01 General

This opening chapter delivers the general assembly drawing, full machine specifications, a comprehensive weight table for transporting and handling components, and a complete list of lubricants and water with ambient temperature charts. The specifications section covers operating weight, bucket capacity, rated load, travel speeds, gradeability, turning radius, dimensions, engine data, power train details, brake system type, hydraulic system pressures and pump delivery rates, cylinder bore and stroke dimensions, and tire and inflation pressure data. The weight table gives individual component weights for the engine, radiator, transmission, torque converter, drive shafts, axles, differentials, planetary carriers, wheels, tires, steering components, brake valves, hydraulic tank, pumps, control valves, lift and bucket cylinders, frames, bucket, bellcrank, counterweight, fuel tank, cab, and ROPS structures. The lubricant chart specifies engine oil, transmission oil, hydraulic oil, axle oil, grease, diesel fuel, and cooling system water requirements across the full ambient temperature range.

10 Structure and Function

This extensive chapter explains the structure and operation of every major system on the WA420-3. The power train section begins with the complete power flow from the S6D108 engine through the torque converter, transmission, drive shafts, differentials, final drives, and wheels. The torque converter chapter details the TCA37-2Z three-element, single-stage, single-phase unit with a stall torque ratio of 3.27, covering the path of motive force and oil flow through the pump, turbine, and stator. The transmission section provides a complete breakdown of the multiple-shaft transmission with its six hydraulically actuated clutches providing four forward and four reverse speeds, including detailed clutch operation, FORWARD and REVERSE clutch configurations, and gear train arrangements for each speed range. The transmission control valve coverage includes the upper and lower valve bodies, priority valve, main relief valve, pilot reducing valve, quick return valve, modulation valve, accumulator, directional selector valve, H-L selector valve, range selector valve, parking brake valve, torque converter outlet port valve, and emergency manual spool. The solenoid valve operation and actuation table for each gear range is included. The axle and differential chapter explains the spiral bevel gear reduction, torque proportioning differential operation on straight travel and turns, and the planetary final drive. The steering system section covers the steering valve, orbit-roll valve, stop valve, emergency steering pump, diverter valve, flow amp, demand spool, and the complete steering hydraulic circuit. The brake chapter details the brake piping, brake circuit diagram, brake valve operation for both right and left pedals, charge valve, accumulator, slack adjuster, wet-type multiple-disc brakes, parking brake control, parking brake valve, and parking brake emergency release solenoid valve. The hydraulic piping chapter includes the work equipment hydraulic system diagram, circuit diagram, work equipment lever linkage, hydraulic tank with filter suction valve and breather, PPC valve, PPC relief valve, accumulator for the PPC valve, main control valve with boom and bucket spools, safety valves with suction, suction valve, slow return valve, and cut-off valve. The work equipment linkage, bucket, bucket positioner, and boom kick-out systems are covered with their proximity switch operations. The cab, ROPS cab, and air conditioner sections describe the operator environment. The electrical circuit diagram, machine monitor system, main monitor, maintenance monitor, work equipment control system, E.C.S.S., sensors, engine starting circuit, engine stop circuit, preheating circuit, electric transmission control, kick-down switch, transmission cut-off switch, and electric parking brake control complete this chapter.

20 Testing and Adjusting

This chapter provides the testing and adjusting procedures for the WA420-3 Wheel Loader. It includes checks to be performed before and after repairs, adjustments to be made upon completion of checks and repairs, and troubleshooting charts correlating problems to causes. This section supports systematic diagnosis and correction of issues across the engine, power train, steering, brakes, hydraulic system, and electrical systems.

30 Disassembly and Assembly

This chapter explains the order to be followed when removing, installing, disassembling, or assembling each component of the WA420-3, along with the precautions to be taken for these operations. Component-level procedures cover the engine, torque converter, transmission, drive shafts, axles, differentials, final drives, steering system, brake system, hydraulic pumps, control valves, cylinders, work equipment linkage, cab, and electrical components.

40 Maintenance Standard

This chapter gives the judgement standards used when inspecting disassembled parts, providing the wear limits, clearances, and tolerance values needed to determine whether components can be reused or must be replaced.

Why This Shop Manual Matters

The Komatsu WA420-3 Wheel Loader Shop Manual is the definitive technical reference for maintaining and repairing this machine. The WA420-3 is a 18,300 to 18,590 kg class wheel loader powered by the Komatsu SA6D108 turbocharged diesel engine producing 161.8 kW (217 HP) at 2,200 rpm with 847 Nm of torque at 1,500 rpm. Whether you are troubleshooting a transmission that will not shift, adjusting the modulation valve for smooth gear changes, diagnosing a brake issue, or rebuilding a final drive, this manual provides the procedures, specifications, and judgement standards required to complete the job correctly.

The depth of technical information in this 828-page manual is exceptional. The structure and function chapter alone spans over 170 pages of detailed system explanations, hydraulic circuit diagrams, cross-sectional illustrations, and operation descriptions. The transmission control valve section walks through the oil flow through the priority valve, main relief valve, modulation valve, quick return valve, and accumulator during every shift sequence. The modulation valve operation is described across four distinct phases from clutch fully engaged through the complete pressure rise during gear shifting. The quick return valve operation is documented for each stage of the shift. The torque proportioning differential is explained with the actual traction ratio of 1:1.38 and the effect on tire life and operating efficiency. The accumulator operation for both the brake circuit and the PPC circuit is covered with charging pressures and gas volumes. The hydraulic system diagrams show every component and connection in the work equipment, steering, and brake circuits.

Systems and Components Covered

The manual covers the complete machine including the engine (SA6D108, 6-cylinder, 108 mm bore x 130 mm stroke, 7.15 liter displacement), torque converter (Komatsu TCA37-2Z), transmission (multiple shaft type with six hydraulically actuated clutches), drive shafts (center, front, and rear with universal and sliding joints), axles (front and rear with spiral bevel gear reduction and torque proportioning differentials), final drives (planetary gear single stage), brakes (front and rear wheel independent sealed multiple-disc wet-type with hydraulic booster, plus parking brake on transmission output shaft), steering (fully hydraulic power steering with orbit-roll valve and emergency steering pump), hydraulic system (gear pump delivering 217 L/min for work equipment, 111 L/min switch pump, 137 L/min steering pump, 62 L/min PPC pump), control valve (2-spool type with 20.58 MPa set pressure), cylinders (boom 2 x 160 mm bore x 846 mm stroke, bucket 1 x 200 mm bore x 498 mm stroke, steering 2 x 90 mm bore x 442 mm stroke), work equipment (single link, flat edge bucket with bolt-on cutting edge), cab and ROPS structures, air conditioner, and complete electrical system with machine monitor, maintenance monitor, and work equipment control system.

Get Your Komatsu WA420-3 Shop Manual Today

This Komatsu WA420-3 Wheel Loader Shop Manual PDF gives you the same technical information used by professional service technicians to maintain, diagnose, and repair the WA420-3. With instant PDF delivery, you can access the complete manual on any device, search across all 828 pages, and print the sections you need for the workshop. Whether you are a fleet owner, a maintenance manager, or an independent technician, this manual is an essential tool for keeping your WA420-3 wheel loader operating at peak performance. Every procedure, specification, torque value, pressure setting, and judgement standard you need is contained in this single comprehensive document. Do not risk costly mistakes by working without the correct technical data. Order your copy now and have the complete factory shop manual available immediately after checkout.

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