Factory-level coverage of the R320S and R320S(B) wheel loader fills these 381 pages, OEM #RY911-21080, running from engine internals to the front loader. The hydraulic section maps every circuit schematic with full oil-flow routing, and the wiring diagrams trace each electrical circuit on the machine. Mechanics get 54 pages of torque tables, 100 pages of step-by-step disassembly and reassembly, plus exploded views across drivetrain, brakes, steering, and front loader. Ten pages of troubleshooting charts cover engine, hydraulic, and front loader faults the factory way. Snug that 1/2-inch hydraulic hose union nut to 58.8 to 63.7 N·m, torque M10 7T fasteners to 49 to 55 N·m: this is the data sheet, not a forum thread. With your loader down, search any spec by keyword and pull it up on a tablet beside the machine.
What's Inside This Kubota R320S, R320S(B) Manual
| System | Pages | Key Topics |
|---|---|---|
| I Information | 5-20 | Safety First, Work Safety, Safety Decals, Table of Main Specifications, Dimensions |
| G General | 21-41 | Machine Indentification, Engine Indentification, General Precautions, Handling Precautions for Electrical Parts and Wiring, Types of Oil, Tightening Torques |
| 1 Engine | 42-126 | Troubleshooting, Service Standard, Tightening Torques, Disassembly, Reassembly and Maintenance, Radiator, Accelerator |
| 2 Hydraulic System | 127-186 | Hydraulic Circuit, Hydraulic Equipment Schematic, Oil Flow, Lst Pump Specifications, Lst Motor Specifications |
| 3 Power Train | 187-207 | Drivetrain, Transmission, Front Axle and Rear Axle Differential Cases |
| 4 Brakes | 208-230 | Brake System, Brake Components, Master Cylinder, Negative Brake, Brake Line Air Bleeding Procedure, Brake Performance Measurements |
| 5 Steering | 231-266 | Steering System, Steering Controller Specifications, Steering Cylinder Specifications, Steering Wheel Unit, Steering Controller, Steering Cylinder |
| 6 Front Loader | 267-297 | Front Loader, Front, Implement Control Lever, Control Valve, Measuring Front Performance, Troubleshooting (Front) |
| 7 Frame | 298-307 | Center Pin Removal and Installation, Measuring the Center Pin and Bushing, Canopy Assembly, Weight Assembly |
| 8 Electrical System | 308-338 | Electrical Device Layout, Electrical Wiring, Inspections, Circuit Diagram, Electrical Wiring Diagram |
| 9 Backhoe | 339-381 | Oil Flow, Diagram of Hydraulic Circuit, Control Valve Specifications, Hydraulic Cylinder Specifications, Backhoe Operation Schematic, Routing of Hydraulic Hoses |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| General Use Screws, Bolts and Nuts (M6, No-grade or 4T) | 7.9 to 9.3 N·m (0.80 to 0.95 kgf·m, 5.8 to 6.8 lbf·ft) | p. 34 |
| General Use Screws, Bolts and Nuts (M10, 7T) | 49 to 55 N·m (5.0 to 5.7 kgf·m, 37 to 41 lbf·ft) | p. 34 |
| Operating weight (with Rops/Fops) | 2220 kg | p. 16 |
| Horsepower (SAE gross) | 18.5 kW | p. 16 |
| Engine Valve clearance | 0.145 to 0.185 mm | p. 44 |
| Engine Compression (Factory Specification) | 3.72 to 4.12 MPa | p. 56 |
| M10 Bolt Torque (No-grade or 4T) | 40 to 45 N·m | p. 61 |
| Cylinder head screw torque | 63.7 to 68.6 N·m | p. 62 |
| LST pump capacity | 26 cc/rev | p. 133 |
| Steering controller displacement volume | 100 cc/rev | p. 235 |
| R320S | ||
| Overall length | 3575 mm | p. 16 |
| R320S(B) | ||
| Overall length | 3835 mm | p. 16 |
Kubota R320S, R320S(B) Common Problems This Manual Covers
Kubota R320S wheel loader weak or no forward and reverse drive under heavy load. p. 133
Inspect the hydrostatic drive circuit. Measure LST pump capacity against the 26 cc/rev spec on page 133. Swap the forward and reverse relief valves to isolate the fault, then replace any scored valves and torque the hydraulic hose union nuts to 7.8 to 11.8 N·m.
Manual Section: 2 Hydraulic SystemBucket and lift cylinder lack power or speed and drop when control lever is released. p. 270
Test the front loader hydraulic circuit pressure. Connect a gauge and confirm the main relief valve reaches its 17.2 MPa setting on page 270. If pressure runs low, adjust the relief valve or replace worn internal seals. Torque any reinstalled M6 general-use bolts to 7.9 to 9.3 N·m.
Manual Section: 6 Front LoaderBlack or thick grey exhaust with low power when trying to accelerate the machine.
Check the fuel system and air intake for restrictions. Work the troubleshooting charts to isolate the combustion fault. Measure engine compression, then confirm valve clearance falls within 0.145 to 0.185 mm on page 44. Clean or swap the air filter element right away.
Manual Section: 1 EngineSteering wheel is difficult to turn or binds up during tight directional changes. p. 235
Trace the steering circuit lines for pinched hoses or severe leaks. Verify the steering controller displacement meets the 100 cc/rev spec on page 235. Drain the contaminated hydraulic fluid, replace the filters, and refill the tank. Bleed the steering system fully before testing under load.
Manual Section: 5 SteeringFrequently Asked Questions
What are the replacement specifications for hydrostatic relief valves?
The LST high-pressure relief valve is rated at 32.5 MPa (331 kgf/cm2, 4710 psi), measured at 3.8 to 5.6 L/min (1.0 to 1.5 US gal/min) and 2600 to 2700 rpm (page 133). For the front loader's main and overload relief valves, the manual says to replace them as an assembly if a problem shows up rather than disassemble them (pages 290-291).
What are the replacement specifications for hydraulic filters?
Per the maintenance table on page 41, the LST filter, return filter, and suction filter all get replaced at regular intervals. The LST circuit itself runs a 10 µ filter.
How quickly can I access this Kubota R320S, R320S(B) manual after buying?
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Can I print specific sections of this Kubota R320S, R320S(B) Workshop Manual?
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Are there hydraulic schematics in this Kubota R320S, R320S(B) manual?
Yes, this Kubota R320S, R320S(B) Workshop Manual includes hydraulic system diagrams, circuit schematics, and component specifications.
Document Quality
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