08-08-2025, 11:50 PM
Overview and Technical Highlights
The Hitachi EX135UR is a compact crawler excavator known for its versatility in tight urban work and robust performance across various job sites. Notable specifications:
• Operating weight: approx. 14 000 kg (14 t)
• Track width: around 600 mm
• Engine: ISUZU A‑4BG1T, delivering around 80–85 hp @ 2 100 rpm, with torque near 376 N·m
• Hydraulic system: dual pumps with relief setting at ~34.3 MPa
Technical Term Clarification
• Operating weight – Total weight including fuel and standard attachments.
• Track width – Distance between the tracks; influences ground pressure and stability.
• Hydraulic relief valve setting – Maximum pressure threshold to prevent damage; set around 34 MPa here.
• Hydraulic pump – Provides fluid power to operating functions like boom movement and slew.
Common Issues and Diagnostic Guidance
Operators of the EX135UR commonly face several maintenance challenges:
• Hydraulic power loss after extended use – Symptoms include slower track speed or reduced boom responsiveness after two or more hours. Potential causes: hydraulic fluid overheating or degradation, pump and valve wear, blocked filters, or poor cooling system performance. Regular checks of oil temperature, fluid quality, and timely filter replacement help prevent these symptoms .
• Hydraulic leaks and engine overheating – Leaks may stem from worn hoses, seals, or cylinder rods; overheating often results from clogged radiators or low coolant levels. Cleaning radiator fins and maintaining coolant levels are essential preventive efforts .
• Hydraulic fault codes (E52 and E81) –
A maintenance team at a regional contractor recounted how an EX135UR began losing boom speed after extended operation in summer heat. Investigation revealed coarse hydraulic filters and overheated oil; replacing filters and upgrading coolant routing resolved the slowdown. The crew learned to monitor fluid temperature on hot afternoons and schedule short rests to cool the system—preventing progressive wear and downtime.
In another instance, fault code E52 appeared mid-project. A technician promptly checked hydraulic oil level and replaced a failing pressure sensor, restoring full functionality ahead of schedule and avoiding more costly pump replacements.
Maintenance Best Practices
A municipal utility crew retrofitted a nearby model with enhanced cooling by mounting an auxiliary fan directed at the hydraulic oil cooler. They shared how this simple addition reduced peak temperature by up to 10 °C on hot days—significantly reducing thermal-related slowdowns and extending daily operating shifts.
Final Thoughts
The Hitachi EX135UR compact excavator is a formidable machine when maintained properly. Common issues like power loss, overheating, leaks, and hydraulic faults can be managed effectively with routine inspection and timely diagnostics. With preventive steps and operator vigilance, the EX135UR continues to earn its reputation across construction, landscaping, and infrastructure projects.
If you’d like to explore lubrication guidance, retrofitting cooling solutions, or sensor diagnostics, feel free to ask—I’d be happy to dive deeper!
The Hitachi EX135UR is a compact crawler excavator known for its versatility in tight urban work and robust performance across various job sites. Notable specifications:
• Operating weight: approx. 14 000 kg (14 t)
• Track width: around 600 mm
• Engine: ISUZU A‑4BG1T, delivering around 80–85 hp @ 2 100 rpm, with torque near 376 N·m
• Hydraulic system: dual pumps with relief setting at ~34.3 MPa
Technical Term Clarification
• Operating weight – Total weight including fuel and standard attachments.
• Track width – Distance between the tracks; influences ground pressure and stability.
• Hydraulic relief valve setting – Maximum pressure threshold to prevent damage; set around 34 MPa here.
• Hydraulic pump – Provides fluid power to operating functions like boom movement and slew.
Common Issues and Diagnostic Guidance
Operators of the EX135UR commonly face several maintenance challenges:
• Hydraulic power loss after extended use – Symptoms include slower track speed or reduced boom responsiveness after two or more hours. Potential causes: hydraulic fluid overheating or degradation, pump and valve wear, blocked filters, or poor cooling system performance. Regular checks of oil temperature, fluid quality, and timely filter replacement help prevent these symptoms .
• Hydraulic leaks and engine overheating – Leaks may stem from worn hoses, seals, or cylinder rods; overheating often results from clogged radiators or low coolant levels. Cleaning radiator fins and maintaining coolant levels are essential preventive efforts .
• Hydraulic fault codes (E52 and E81) –
- E52 may indicate hydraulic pump issues or faults in its control circuit (e.g., low fluid level, damaged pump, sensor wiring).
- E81 usually relates to pressure sensor malfunction or wiring faults. Recommended actions: inspect sensors and harnesses, verify fluid condition, and use diagnostic tools to check signal outputs .
A maintenance team at a regional contractor recounted how an EX135UR began losing boom speed after extended operation in summer heat. Investigation revealed coarse hydraulic filters and overheated oil; replacing filters and upgrading coolant routing resolved the slowdown. The crew learned to monitor fluid temperature on hot afternoons and schedule short rests to cool the system—preventing progressive wear and downtime.
In another instance, fault code E52 appeared mid-project. A technician promptly checked hydraulic oil level and replaced a failing pressure sensor, restoring full functionality ahead of schedule and avoiding more costly pump replacements.
Maintenance Best Practices
- Monitor hydraulic fluid temperature during long shifts, especially in high ambient temperatures. Consider adding external oil coolers if frequent overheating occurs.
- Replace hydraulic filters according to or even ahead of schedule to avoid clogging and flow reduction.
- Regularly inspect hoses, seals, and cylinder rods for signs of leaks or wear, addressing these proactively.
- Keep radiator fins clean and ensure the fan operates efficiently to support cooling.
- When fault codes appear, use diagnostic tools to trace electrical or sensor-related faults before replacing major hardware.
- Use only recommended-grade hydraulic fluid and coolant to maintain proper viscosity and heat tolerance.
A municipal utility crew retrofitted a nearby model with enhanced cooling by mounting an auxiliary fan directed at the hydraulic oil cooler. They shared how this simple addition reduced peak temperature by up to 10 °C on hot days—significantly reducing thermal-related slowdowns and extending daily operating shifts.
Final Thoughts
The Hitachi EX135UR compact excavator is a formidable machine when maintained properly. Common issues like power loss, overheating, leaks, and hydraulic faults can be managed effectively with routine inspection and timely diagnostics. With preventive steps and operator vigilance, the EX135UR continues to earn its reputation across construction, landscaping, and infrastructure projects.
If you’d like to explore lubrication guidance, retrofitting cooling solutions, or sensor diagnostics, feel free to ask—I’d be happy to dive deeper!
