Analysis of Typical Volvo EC25 Hydraulic pump Failures

Volvo excavators are renowned for their outstanding hydraulic system performance, but even the most advanced equipment can encounter hydraulic system failures. Understanding these common issues and their solutions is crucial for ensuring the equipment operates at its best. This article will provide a detailed analysis of the typical faults in the Volvo EC25 hydraulic pump and offer corresponding troubleshooting advice.

Analysis of Slow or Weak Actions

When the Volvo EC25 hydraulic pump encounters issues of slow or weak actions, several potential faults may be present:

Low Main Pump Pressure

Volvo EC25 hydraulic pump's main pump pressure being low is a common reason for weak actions. Under normal conditions, this hydraulic pump should output oil pressure ≥30MPa. If the wear between the main pump plunger and the cylinder block exceeds the standard, or if the contact area between the cylinder block end face and the distribution plate is insufficient, it will cause low output pressure from the main pump, leading to weak machine operation.

Main Pump Output Flow Control Valve Group Fault

If the flow control valve group of the Volvo EC25 hydraulic pump malfunctions, the main pump might remain in a low flow state. This would result in slow or weak actions during excavator operation.

Low Output Control Pressure of Relief Valve

In the Volvo EC25 hydraulic pump system, the relief valve is responsible for reducing and stabilizing the main pump output oil pressure at 3.3MPa. If the cone valve core of the relief valve cannot close properly due to dirty oil, it will lead to low control oil pressure, further affecting the main control valve of the working device, causing weak overall performance.

Low Overflow Pressure of Main Relief Valve

The main relief valve in the Volvo EC25 hydraulic pump system limits the maximum pressure of the entire hydraulic system to 32.5MPa. If the valve core's small hole is blocked due to oil quality issues, or if the set overflow pressure is too low, it will cause the actual overflow pressure to be lower, thereby affecting the overall system pressure.

Unload Valve Fault

A fault in the unload valve will cause the Volvo EC25 hydraulic pump's main pump to fail to effectively return hydraulic oil to the tank, making it impossible for the system to establish high pressure, thus causing weak actions during excavator operation.

Analysis of Hydraulic Excavator Walking Deviation Fault

The problem of walking deviation is also common in the Volvo EC25 hydraulic pump system and usually involves the following factors:

Track Tension Check

Different track tensions can affect the walking direction. If the left and right track tensions are inconsistent, it may cause walking deviation.

Oil Pump Performance Check

Check the oil supply of the left and right pumps in the Volvo EC25 hydraulic pump under the ”F“ mode. If the oil supply is inconsistent, it will also cause walking deviation.

Hydraulic Motor Performance Check

If the performance of the left and right hydraulic motors differs, their operation will also vary, leading to walking deviation.

Central Swivel Joint Seal Check

If the central swivel joint seal is damaged, it will cause uneven oil supply to the left and right sides, resulting in walking deviation.

Understanding the common faults and solutions of the Volvo EC25 hydraulic pump is crucial for maintaining the normal operation of the excavator. By performing timely checks and maintenance, these hydraulic system faults can be effectively prevented and resolved, ensuring efficient equipment operation.