Volvo EW145B Wheeled Excavator: Electrical & Hydraulic Systems Explained

[MikePhua]

Overview of the EW145B Powertrain
The Volvo EW145B features a turbocharged, 6-cylinder diesel engine that provides hydraulic power to drive pumps, motors, and auxiliary circuits . Primary power is transferred from the engine to the main hydraulic pump through a flexible coupling, smoothing torsional loads .
Once pressurized by the pump, hydraulic fluid flows through the main control valve to:

• The travel motors, which power the front and rear axles via a transfer gearbox and propeller shafts
  
• The boom, arm, and bucket cylinders, along with slew and work circuits
  
• Various safety and brake circuits controlling steering, parking brakes, and more
  
  

Powertrain Features Simplified

• Remote control pedal governs speed by adjusting engine RPM and hydraulic flow
  
• Forward/reverse solenoid directs fluid to the travel motor for motion direction
  
• Travel interlock logic: ensures engine and pump speed respond to highest demand between pedal and engine speed switch
  
  

Hydraulic Circuit Architecture
The machine’s hydraulic architecture includes:

• Gear pumps for travel and steering
  
• A comprehensive network of control valves: main control, clutch valves (for low-speed), brake valves, shuttle valves, and proportional valves
  
• A piping system that routes pressure to travel motors, brakes, axles, and accessories
  
  

Pressure debits are monitored at specific ports (e.g. P1, P2) above the transfer gearbox and brake/clutch valves for maintenance checks .
Electrical System Integration
While detailed electrical schematics are proprietary, Volvo’s service manuals and electrical wiring diagrams include:

• ECU communication lines among Engine ECU (E‑ECU), Travel ECU (V‑ECU), pressure sensors, and solenoid valves
  
• Fault detection for proportional valve outputs (e.g. ER32 codes) tied to voltage thresholds on JA56 output lines
  
• Guidelines for diagnosing communication faults and component failures using fault codes like ER11‑02, ER12‑02, ER13‑09 etc
  

Technicians use Volvo’s Tech Tool to run diagnostics such as fuel system checks, PRV resets, injector tests, EGR tests, and more .
Terminology You Should Know

• Main Pump: Provides hydraulic pressure for all movement systems
  
• Travel Motor: Hydraulic motor that drives the wheels
  
• Control Valve: Distributes pressure to appropriate actuators
  
• Proportional Valve: Fine controls pressure or flow based on ECU commands
  
• Travel Interlock: Logic that manages engine/pump based on input demand
  
• ER Codes: Electrical fault codes indicating issues with voltage or communication
  
• Tech Tool: Volvo’s diagnostic software used for ECU interactions and fault resolution
  

Maintenance & Troubleshooting Tips

• Regularly test travel pressure at designated ports (P1, P2) to verify pump health and detect pressure loss
  
• Inspect piping and solenoid connectors for leaks or loose fittings
  
• Monitor for electrical fault codes; ER32‑03/04/05 often indicate proportional valve feedback issues
  
• Check for ECU communication faults (ER11‑02, ER12‑02, ER13‑09) by inspecting relays, connector corrosion, or voltage irregularities
  
• Use Tech Tool to reset pressure relief valves, conduct cylinder compression tests, and perform injector or EGR checks as needed
  

Real‑World Application
One technician shared diagnosing hydraulic drive issues by probing pressure sensors and noting inconsistent readings. After tightening connectors and replacing a weak solenoid valve, both travel and boom circuits regained responsiveness.
Another operator reported the appearance of ER32‑04 codes when attempting to use auxiliary hydraulic attachments. Checking the proportional flow control valve and wiring harness resolved the issue, restoring proper hammer/flow control function.
Summary List of Key Insights

• Engine hydraulic power routed via main pump, control valves, travel motors, and structural axles
  
• Speed controlled by pedal and mode switch via servo-hydraulics and ECUs
  
• Proportional valves and pressure sensors communicate feedback through ER fault codes
  
• Trouble codes help trace component issues—ER32 indicates proportional valve voltage faults
  
• Tech Tool diagnostics essential for component testing and clearing codes
  

Conclusion
The Volvo EW145B’s hydraulic and electrical systems offer reliable performance when maintained per service guidelines. Understanding pump and valve layout, electrical fault logic, and pressure/feedback systems enables efficient troubleshooting and preventive maintenance. With vigilance and proper diagnostic tools, operators and technicians can keep these excavators running smoothly and efficiently.
Let me know if you’d like help interpreting specific circuit diagrams or fault codes!