Part of the Hitachi Repair Manuals.
The ZX75US is Hitachi's 7100 kg reduced tail swing machine, and this file covers it the way a shop actually needs: full workshop teardown, troubleshooting with operational performance tests, and the operational principle pages where the pressure and flow settings live. The workshop side walks swing device removal and overhaul, main pump, control valves, the complete undercarriage down to the rubber crawler, front attachment pins and bushings, plus a full engine section with disassembly, fuel injection, starter and alternator. The troubleshooting volume carries a fault code list with A and B flowcharts and electrical inspection. Component spec pages give you real numbers - travel relief at 31.4 MPa, main pumps at 68.8 L/min x 2, swing device bolts at 540 N.m.
What's Inside This Repair Manual
| System | Pages | Key Topics |
|---|---|---|
| Workshop Manual: Introduction and Safety | 1-30 | Manual Composition, Safety Precautions, Service Tool Notes |
| Workshop Manual: General Information | 31-52 | Precautions for Disassembling and Assembling, Maintenance Standard Terminology, Tightening Torque Specification, Torque Chart, Piping Joint |
| Workshop Manual: Upperstructure | 53-228 | Cab and Cab Glass Dimensions, Swing Device Removal and Overhaul, Main Pump, Control Valve, Pilot Valve |
| Workshop Manual: Undercarriage | 229-312 | Swing Bearing, Travel Device, Front Idler, Track Adjuster, Rollers, Sprocket, Rubber Crawler |
| Workshop Manual: Front Attachment | 313-358 | Front Attachment Removal, Arm and Bucket Connection Dimensions, Cylinders, Bushings and Pins |
| Engine and Accessory | 359-580 | General Repair Instructions, Engine Assembly Disassembly and Reassembly, Lubrication, Cooling, Fuel Injection, Starter and Alternator |
| Troubleshooting Manual: Introduction and Safety | 581-611 | Volume Composition, Diagnostic Conventions, Safety Notes for Testing a Running Machine |
| Operational Performance Test | 612-669 | Preparation for Performance Tests, Engine and Excavator Tests, Component Test, Primary and Secondary Pilot Pressure, Adjustment |
| Troubleshooting | 670-842 | Diagnosing Procedure, Fault Code List, Troubleshooting a and B Flowcharts, Electrical System Inspection |
| Operational Principle: General | 843-863 | Specifications, Working Ranges, Machine Transportation Dimensions, Component Layout |
| Operational Principle: System | 864-913 | Control System Outline, Engine Control, Pump Control, Valve Control, Electrical System |
| Operational Principle: Component Operation | 914-991 | Main Pumps, Pilot Valve, Control Valve, Swing Device, Travel Device, Signal Control Valve |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Control valve 1 main relief - travel | 31.4 MPa (320 kgf/cm2, 4550 psi) at 33 L/min | p. 860 |
| Control valve 1 main relief - front attachment | 26.0 MPa (265 kgf/cm2, 3770 psi) at 43 L/min | p. 860 |
| Control valve 1 overload relief - boom, arm, bucket | 27.9 MPa (285 kgf/cm2, 4050 psi) | p. 860 |
| Control valve 2 main relief | 26 MPa (265 kgf/cm2, 3770 psi) at 43 L/min | p. 860 |
| Control valve 2 overload relief - blade | 28 MPa (285 kgf/cm2, 4050 psi) | p. 860 |
| Valve unit relief | 25 MPa (255 kgf/cm2, 3630 psi) at 63 L/min | p. 860 |
| Travel brake valve relief | 31.3 MPa (320 kgf/cm2, 4550 psi) | p. 861 |
| Swing parking brake release pressure at full stroke | 1.18 +/- 0.15 MPa (12 +/- 1.5 kgf/cm2, 171 +/- 21 psi) | p. 860 |
| Travel parking brake cracking pressure - slow / fast | 0.88 / 1.57 MPa (9.0 / 16 kgf/cm2, 128 / 228 psi) | p. 861 |
| Oil cooler bypass check valve cracking pressure | 294 kPa (3.0 kgf/cm2, 42 psi) at 5 L/min | p. 861 |
| Main pumps 1 and 2 maximum flow, theoretical | 68.8 L/min (18.2 US gpm) x 2 | p. 860 |
| Main pump 3 gear pump maximum flow, theoretical | 40.7 L/min (10.7 US gpm) | p. 860 |
| Pilot pump maximum flow, theoretical | 20.3 L/min (5.4 US gpm) | p. 860 |
| Engine compression pressure | 2.94 MPa (30 kgf/cm2) at 250 min-1 | p. 857 |
| Nozzle injection pressure | 18.1 MPa (150 kgf/cm2) | p. 857 |
| Engine maximum output torque | more than 201 N.m (20.5 kgf.m) at 1600 min-1 | p. 857 |
| Swing device mounting bolt torque | 540 N.m (55 kgf.m, 400 lbf.ft) | p. 41 |
| Hydraulic oil tank mounting bolt torque | 210 N.m (21.5 kgf.m, 155 lbf.ft) | p. 41 |
| Engine cushion rubber mounting bolt torque | 270 N.m (27.5 kgf.m, 200 lbf.ft) | p. 41 |
| Operating weight with a 1.62 m arm | 7100 kg (15700 lb) | p. 848 |
