Part of the Kubota Repair Manuals.
This is the Kubota BH77 backhoe workshop manual, the factory service book for the BH77 loader-backhoe attachment (publication 9Y121-05440). It focuses on the hydraulic system that drives the boom, dipperstick, bucket, swing, and stabilizers.
Its 75 pages move from safety information and machine identification into the mechanism section, which explains the hydraulic circuit, the control valve structure and operation, the overload relief valve, and the hydraulic cylinders. The servicing section then covers troubleshooting, servicing specifications, tightening torques, and full dismounting, disassembly, and assembly procedures.
This is the manual to reach for when a boom or swing function loses power, the controls feel vague, or you need relief valve pressures and torque figures to reassemble the backhoe correctly. Lubricant tables and torque values for hydraulic fittings and fasteners are included.
What's Inside This Manual
| System | Pages | Key Topics |
|---|---|---|
| General | Backhoe Identification, Lubricants, Tightening Torques (Stud Bolts, American Standard Screws, Bolts and Nuts with Unc or Unf Threads, Plugs, Hydraulic Fittings) | |
| Mechanism | Hydraulic Circuit, Control Valve (Structure, Operation, Overload Relief Valve), Hydraulic Cylinder | |
| Servicing | Troubleshooting, Servicing Specifications, Tightening Torques |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Relief valve setting pressure for Boom (A5, B5 port side) | 20.6 to 21.0 MPa (210 to 215 kgf/cm², 2990 to 3050 psi) | p. 44 |
| Tightening torque for Control lever step mounting screw | 48 to 55 N·m (4.9 to 5.7 kgf·m, 36 to 41 lbf·ft) | p. 58 |
| Tightening torque for Hydraulic hose fitting, Flare nut (UNF) 9/16 | 22 to 25 N-m (2.3 to 2.5 kgf-m, 17 to 18 lbf-ft) | p. 20 |
| Transport Height | 2051 mm | p. 11 |
| Maximum Digging Depth | 2378 mm | p. 11 |
| Digging Force (With bucket cylinder) | 15220 N | p. 12 |
| Boom cylinder, extend (Cycle Time) | 3.5 seconds | p. 12 |
| Transmission case capacity (B3200/B3300SU) | 14.5 L | p. 18 |
| Relief Valve Setting Pressure (B3200 Tractor) | 13.3 to 14.3 MPa | p. 48 |
| Swing Frame Fulcrum Pin to Bush (Clearance) | 0.200 to 0.269 mm | p. 48 |
| Thrust Washer (Thickness) | 2.45 to 2.82 mm | p. 49 |
