Getting a Komatsu WB146-5 backhoe loader through a transmission or axle rebuild on the first attempt is the job these 586 pages of Komatsu shop manual CEBM016503 were written for. Transmission overhaul alone fills close to a fifth of this Komatsu WB146-5 service manual PDF, taking the torque converter, clutch packs, gear shafts and valve body apart and back together, while engine removal and both axle overhauls take nearly as much again. Testing and troubleshooting get a section of their own, built around a standard value table and a troubleshooting guide covering the brake system and relief valves. Set main control valve pressure at 249 kg/cm² (permissible 238 to 264), and expect 178 kg/cm² at the steering unit; boom cylinder piston nuts take 1800 to 2200 Nm. A guessed torque means a second teardown. Bookmarked by section and fully text searchable, this copy is yours to keep and reopen every time your WB146-5 comes in for work.
What's Inside This Komatsu WB146-5 Manual
| System | Pages | Key Topics |
|---|---|---|
| General | 29-40 | Specification Drawing, Machine Systems Specifications |
| Structure, Function and Maintenance Standard | 41-136 | Power Train, Transmission, Hydraulic Pump, Main Control Valve, Clss |
| Testing, Adjusting and Troubleshooting | 137-206 | Standard Value Table, Brake System, Relief Valves, Troubleshooting Guide |
| General Disassembly and Assembly Procedures | 207-227 | Manual Usage, Safety Precautions, Special Tools, Connector Repair, Bleeding Air |
| Engine and Cooling System Components | 228-259 | Engine Hood, Radiator, Muffler, Air Filter, Turbocharger, Refrigerant Compressor, Fuel Tank |
| Cab, Steering, and Hydraulic Tank | 260-284 | Steering and Dash Assembly, Cab Removal, Hydraulic Oil Tank, Hydraulic Pump |
| Transmission Overhaul | 285-396 | Transmission Removal, Torque Converter, Clutch Packs, Gear Shafts, Valve Body, 4WD Solenoid Valve |
| Engine and Axle Assemblies | 397-499 | Engine Removal, Front Axle Assembly, Front Axle Overhaul, Rear Axle Assembly, Rear Axle Overhaul |
| Work Equipment and Cylinders | 500-560 | Front Loader PPC Valve, Front-End Loader Assembly, Backhoe PPC Valve, Backhoe Assembly, Work Equipment Cylinder Overhaul |
| Others | 561-586 | Hydraulic Circuit, Electrical Schematic |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Tightening torque of hose nuts (Nominal No. 02) | 19.6 - 29.4 Nm | p. 20 |
| Tightening torque of hose nuts (Nominal No. 03) | 29.4 - 68.6 Nm | p. 20 |
| Main valve pressure (Control valve) | 249 kg/cm² (Permissible: 238 - 264 kg/cm²) | p. 141 |
| Steering unit pressure | 178 kg/cm² (Permissible: 173 - 188 kg/cm²) | p. 141 |
| Boom Cylinder Piston Nut Torque | 1800 ~ 2200 Nm (1328 ~ 1623 ft/lbs) | p. 114 |
| Boom Cylinder Head Torque | 630 ~ 770 Nm (465 ~ 568 ft/lbs) | p. 114 |
| Hydraulic oil capacity | Approximately 40 liters (10.5 gal) | p. 275 |
| Drive shaft bolts | 38 ± 1 N·m (28 ± 1 lbf ft) | p. 284 |
| Pump bolts | 220 N·m (162 lbf ft) | p. 284 |
| Drive plate thickness | 2.5 ± 0.05 mm (0.098 ± 0.002 in) | p. 352 |
Komatsu WB146-5 Common Problems This Manual Covers
Komatsu WB146-5 backhoe loader main control valve pressure testing below the 238 kg/cm² permissible minimum
Measure main valve pressure at the control valve following page 141. It should read 249 kg/cm², with a permissible range of 238 to 264 kg/cm². Check steering unit pressure against 178 kg/cm² (173 to 188 kg/cm²) at the same time. Then run the engine speed check with the converter stalled and the hydraulic pump under load.
Manual Section: Testing, Adjusting and Troubleshooting p. 141Front loader boom, bucket, backhoe boom, arm or outriggers hydraulic circuit drifting down
Test drift one circuit at a time using the Hydraulic Drift Troubleshooting checks before you pull anything. If the fault traces to the cylinder, overhaul it. Heat the new sealing rings to 50 to 60°C (122 to 140°F) following page 553. Then torque the boom cylinder piston nut to 1800 to 2200 Nm and the cylinder head to 630 to 770 Nm on page 114.
Manual Section: Hydraulic Drift TroubleshootingTransmission showing reduced power transmission and overheating, or gear shift will not engage
Check the transmission oil level first. Refill capacity is 20.2 liters per page 34. If power stays down, tear down the clutch packs and measure the clutch plates against 1.75 ± 0.05 mm, with no more than 0.2 mm wear each side, on page 352. Verify clutch pack backlash at 2.3 to 4.3 mm following page 356.
Manual Section: Transmission TroubleshootingFour wheel drive not engaging, no 4WD power reaching the front axle from the transmission
Verify the complaint using the no 4WD power checks in Transmission Troubleshooting before you touch the axle. If the checks point to the transmission, remove and inspect the 4WD solenoid valve following the Transmission Overhaul procedures from page 285. Confirm the transmission oil level against the 20.2 liter capacity on page 34.
Manual Section: Transmission TroubleshootingFront axle wheel vibration, steering difficulty, or jamming while steering with uneven tire wear
Check front tire pressure against the standard value on page 34 first. Then work through the front axle troubleshooting chart, matching vibration, jamming, noise or half shaft breakage to its listed cause. Follow the Front Axle Overhaul procedures in the axle assemblies section starting on page 397.
Manual Section: Front Axle TroubleshootingAir conditioning not cooling properly with abnormal LP and HP side pressure readings on the gauges
Check LP and HP pressures with gauges against the Air Conditioning Troubleshooting conditions. Use the readings to tell a compressor fault apart from a blocked expansion valve, a saturated filter or air infiltration in the circuit. To remove the compressor, follow the Refrigerant Compressor procedure in the Engine and Cooling System Components section from page 228.
Manual Section: Air Conditioning TroubleshootingFrequently Asked Questions
How do you bleed the hydraulic system on a Komatsu WB146-5?
To bleed the hydraulic system, start the engine and run at high idle for 5 minutes to heat the oil. Reduce speed to low idle and extend and retract each cylinder several times, stopping about 100 mm (4 inches) from the end of the stroke. Finally, perform a complete travel of the cylinder until the pump reaches its maximum pressure, and repeat for all cylinders while checking the oil level in the tank. p. 152
What is the standard tightening torque for a 10 mm bolt on the Komatsu WB146-5?
The standard tightening torque for a 10 mm bolt with a 17 mm width across flats is 59 - 74 Nm (43.51 - 54.57 lbf ft). p. 19
What is the engine oil capacity for the Komatsu WB146-5?
The engine oil pan capacity for the Komatsu WB146-5 is 11 liters (about 11.6 US qt) specified, and 13 liters (about 13.7 US qt) at refill. p. 37
What is the correct fan belt tension for the engine?
The fan belt tension should be set so that there is a deflection of 10 mm when pressed with a finger force of approximately 10 kgf (22 lbf). The service limit for this deflection is 10 - 15 mm. p. 139
What is the procedure for checking the hydraulic drift of the loader boom?
To check the hydraulic drift of the loader boom, place the machine on level ground with the bucket edge on 10 cm (4 in) blocks. With the engine stopped and oil temperature at 45 - 55 °C, check the position of the boom cylinder. The standard drift is 12 mm, with a permissible limit of 20 mm over 15 minutes. p. 143
How quickly can I access this Komatsu WB146-5 manual after buying?
Straight to your device: 586 pages of searchable Service Manual, downloadable the moment payment goes through.
Can I print a copy of this Komatsu WB146-5 Service Manual for the shop?
Yes. Print individual pages or full chapters for your own shop use, on letter or A4 paper.
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