The reason of the hydraulic motor at low speeds, generating creeping


When the hydraulic motor is at a low speed, the crawling phenomenon is generally caused by the following reasons:

  •    1)The magnitude of friction is not stable.

The normal frictional force increases with speed, while the frictional resistance inside the motor working in the static and low speed regions does not increase when the operating speed increases, but decreases, forming a so-called "negative characteristic" resistance. On the other hand, the hydraulic motor and the load are pushed by the pressure increase after the hydraulic oil is compressed.

When the object is stationary or the speed is low, the resistance is large, and the spring is continuously compressed to increase the thrust. The movement begins only when the spring is compressed until its thrust is greater than the static friction. Once the object starts to move, the resistance suddenly decreases, and the object suddenly accelerates, and the result is that the compression of the spring is reduced, the thrust is reduced, and the object is stopped by the inertia forward for a certain distance. Until the spring compresses again, the thrust increases and the object oscillates again. This is a creep phenomenon for hydraulic motors.

  • 2)The amount of leakage is not stable.

The leakage of the hydraulic motor is not the same at every moment, and it periodically fluctuates with the change of the phase angle of the rotation of the rotor. Because the flow rate entering the motor at low speed is small, the leakage accounts for a large proportion, and the instability of the leakage amount will obviously affect the flow value of the motor work, thus causing fluctuations in the rotational speed.When the motor is running at low speed, its rotating part and the load it carries exhibit less inertia.

The above influence are obvious, and thus there is a crawling phenomenon.

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