Why Does My Excavator Hydraulic Pump Make Abnormal Noises?


A hydraulic system composed of numerous elastomers. Each elastomer will produce resonance and vibration under the action of impact force, rotational unbalanced force, changing friction force, changing inertia force, elastic force, etc., accompanied by noise.

Why Does My Excavator Hydraulic Pump Make Abnormal Noises?

1. The pump has high noise and vibration

In the work of engineering machinery, the hydraulic pump is the main source of noise. The fluid noise of the hydraulic pump is mainly caused by the periodic changes in the pressure flow of the hydraulic pump and the cavitation phenomenon. During the oil suction and oil filling cycle of the hydraulic pump, periodic pressure and flow changes occur, and the stroke pressure pulses cause hydraulic vibration and noise.

Phenomenon ①: Cavitation occurs in the pump

a. Cause of failure: oil temperature is too low or viscosity is too high;

Elimination method: heat the oil or replace the hydraulic oil with a relatively low viscosity (anti-wear hydraulic oil: No. 32 oil in winter, use No. 46 oil in summer).

b. Cause of failure: The suction pipe is too long, too thin, and has too many elbows;

Elimination method: Increase the corresponding diameter of the oil pipe to avoid bending the oil pipe, reduce corresponding losses, and prevent air infiltration.

c. Cause of failure: The oil inlet filter is too small or clogged;

Elimination method: Clean the filter frequently to prevent clogging. In terms of selection, also choose the appropriate filter.

d. Cause of failure: The pump is too high from the liquid level;

Elimination method: Change the pump installation location.

e. Cause of failure: auxiliary pump failure;

Elimination method: Replace or repair.

f. Cause of failure: The pump rotates too fast;

Elimination method: increase the hydraulic pump and reduce the number of motor revolutions.

Phenomenon ②: There are bubbles in the oil

a. Cause of failure: Improper selection of oil;

Elimination method: replace the oil.

b. Cause of failure: The return pipe in the fuel tank is above the liquid level;

Elimination method: extend the tube under the liquid surface.

c. Cause of failure: The liquid level in the fuel tank is too low;

Elimination method: Add oil to the specified range (generally the oil level is 0.8 times the height of the fuel tank).

d. Cause of failure: air enters the oil inlet pipe joint;

Elimination method: Replace or tighten the joint.

e. Cause of failure: The pump shaft oil seal is damaged;

Elimination method: Replace the pump shaft oil seal of the hydraulic system.

f. Cause of failure: The system exhaust is not good;

Elimination method: Re-exhaust.

Phenomenon ③: The pump is worn, or the coaxially between the pump and the prime mover is low

Elimination method:

a. Replacement or repair;

b. System adjustment

2. The hydraulic motor is noisy

Cause of failure ①: Poor pipe joint seal;

Elimination method: Replace seals.

Cause of failure ②: The oil motor is worn or damaged;

Elimination method: Replace or repair.

Cause of failure ③: The coaxiality between the oil motor and the working machine is low;

Elimination method: readjust.

3. The hydraulic cylinder makes a lot of noise

Cause of failure: air enters the cylinder;

Elimination method: Empty the air well.

4. Relief valve squeals

The pressure and flow pulsation of a hydraulic station are determined by its own structure. Pressure pulsation is an exciting force. If various valves in the hydraulic station are not firmly installed, they will vibrate under the action of this exciting force and produce noise. In addition, if the oil filter is not clean, it will cause fluid noise due to its throttling effect on high-pressure oil. The one-way valve selection is unreasonable. If the liquid flows to the one-way valve, the valve inside it will easily vibrate and cause noise. The reversing valve suddenly changes direction, and the flow rate of the hydraulic oil suddenly changes instantly, causing a pressure shock. Cause vibration and noise.

Cause of failure ①: The pressure adjustment is too low or too close to other valves;

Elimination method: Readjust, assemble, or replace.

Cause of failure ②: Poppet valve and valve seat wear;

The needle valve is excessively worn due to frequent opening during use, causing the cone surface of the needle valve and the valve seat to be unable to seal tightly, resulting in unstable pilot flow, pressure fluctuations, and noise.

Elimination method: Replace or repair.

5. Dead bends in pipes or loose fixing clips

Cause of failure: long pipeline and poor fixation;

Elimination method: add pipe clamps, and anti-vibration pads, and install pressure plates.

6. Noise from plunger pump or motor

Cause of failure ①: The oil filter and oil inlet pipe system of the hydraulic pump are clogged or the oil viscosity is too high, causing the vacuum at the oil inlet of the pump to be too low, allowing air to penetrate.

Cause of failure ②: The shaft seals of the hydraulic pump and guide pump are damaged, or the seals are poorly sealed and enter the pipeline, causing air to enter.

Cause of failure ③: The oil level in the tank is too low, and the oil inlet pipe of the hydraulic pump is directly sucked out.

Elimination method: Replace the oil filter, oil seal, and other parts.

As a supplier of construction machinery parts, we can provide different kinds of pump parts to fix your machine. If you are interested in our products, please feel free to contact us.

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