Excavator hydraulic pump pressure

The pressure parameters of excavator hydraulic pumps are core indicators determining operational performance, with significant variations in pressure ranges across different brands and working conditions.

First, Detailed Introduction to Excavator Hydraulic Pump Pressure

The Caterpillar 330GC excavator achieves a maximum main relief pressure of 35,000 kPa, with a swing circuit pressure of 28,400 kPa. The pilot circuit pressure remains stable at approximately 3.9 MPa. This pressure configuration delivers sustained, robust power output during earthmoving and loading operations. The Sumitomo excavator features a dual variable-displacement plunger pump with a standard operating pressure of 34.3 MPa. In boost mode, it reaches 37.3 MPa, delivering explosive power for hard rock crushing and heavy-duty excavation

The 150 excavator maintains a stable 28 MPa during earthmoving tasks, with pressure fluctuating between 35-38 MPa during rock breaking. Under extreme conditions, peak pressure can briefly reach 42 MPa. The XGMA 825 excavator's system pressure is set within the 34-36 MPa range. When shock pressure exceeds 42 MPa, its overload relief protection automatically activates, effectively preventing pump damage. For compact excavators like the Longgong 6065, the main pump's rated pressure typically ranges from 32-34 MPa, while the pilot pump maintains 3.5-4 MPa. Pressure may fluctuate within a reasonable 5%-8% range across different operating modes.

During routine maintenance, system status can be assessed through pump pressure indicators:

1.Low pressure accompanied by sluggish operation typically indicates insufficient hydraulic fluid or pump wear.

2.Severe pressure fluctuations often result from a clogged suction filter.

3.Excessively high pressure coupled with rapid oil temperature rise warrants immediate inspection for stuck relief valves.

Second, Excavator Hydraulic Pump Pressure Measurement Methods

1. Direct Measurement with External Pressure Gauge

This is the most common field maintenance method, suitable for excavator plunger pumps and gear pumps. First, release residual system pressure. Remove the hydraulic oil pressure measurement plug and install a high-pressure gauge with a 40–60 MPa range and a pressure measurement connector. After starting the engine and maintaining high idle speed, push the control lever to its full travel to activate the relief valve. The pressure gauge reading at this point indicates the actual system operating pressure. This method is simple and intuitive, enabling quick determination of whether the main pump pressure reaches its rated value. Local excavator repair shops in Ankang frequently employ this approach to troubleshoot insufficient pressure issues.

2. Electronic Control System Data Reading Method

Mainstream excavator brands are equipped with pressure sensors, allowing real-time pressure readings to be viewed on the cab display. Switch the operating mode to Fast Mode. On the parameter page, NO.31 displays boom pressure, NO.32 shows dipper and swing pressure, while C-1 and C-2 represent P1 and P2 pump pressure values respectively. This method requires no pipeline disassembly, making it suitable for routine pressure monitoring and early detection of abnormal pressure fluctuations. It is particularly well-suited for high-end models like Caterpillar and Komatsu.

3. Manual Static Pressure Test Method

Suitable for factory testing after piston pump assembly. Secure the pump body with the suction port facing upward, seal the discharge port with a cover plate, install a 400 bar pressure gauge, and fill with hydraulic oil. Use pipe wrenches to rotate the splined shaft and drive the pump body. The maximum value displayed on the pressure gauge indicates the static limit pressure. This method quickly verifies pump body sealing performance, preventing pressure leakage failures after installation.

4. Dynamic Pressure Comprehensive Testing Method

Requires a dual-ball valve three-way test circuit. First, close the relief valve to block the return oil path and directly read the working pressure. Then adjust the relief valve to the set pressure, simultaneously acquiring flow and temperature data. Combined with pump body geometric dimensions, this method can also calculate output power.

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