Five Tips to Learn About Hydraulic Pumps and Motors

Five Tips to Learn About Hydraulic Pumps and Motors

Hydraulic pump and hydraulic motor are essential hydraulic components on every excavator, the structure and working principle is very similar, some outside the industry xiaobai sometimes confuse the two things.Some people say that hydraulic pump and hydraulic motor like a pair of lovers, one attack a subject;Some people say that hydraulic pumps and hydraulic motors are like generators and motors, one identity two jobs.Is that right?What is the difference between the two?

Similarities between hydraulic motors and hydraulic pumps:

(1) From the principle, the hydraulic motor and hydraulic pump is reversible, if driven by the motor, the output is hydraulic energy (pressure and flow), this is the hydraulic pump;If the pressure oil is input and the mechanical energy (torque and speed) is output, it becomes a hydraulic motor.


(2) In terms of structure, the two are similar.

hydraulic motor

(3) On the principle of work, both are the use of the change in the sealing capacity for oil absorption and drainage.

For hydraulic pump, when the working volume increases oil absorption, working volume decreases hours to discharge high pressure oil.

For hydraulic motors, when the working volume increases, the high pressure oil will enter and the low pressure oil will be discharged when the working volume decreases.

Differences between hydraulic motors and hydraulic pumps:

(1) Hydraulic pump is the energy device, and hydraulic motor is the executive component.

Hydraulic pump is a conversion device to convert mechanical energy of motor into hydraulic energy, output flow and pressure, in the hope of high volume efficiency; Hydraulic motor is the liquid pressure can be converted into mechanical energy device, output torque and speed, in the hope of high mechanical efficiency.

Komatsu excavator hydraulic pump

(2) The steering of the output shaft of the hydraulic motor must be positive and reverse, so its structure is symmetrical;

And some hydraulic pump (such as gear pump, vane pump, etc.) steering has clear provisions, only one-way rotation, can not change the direction of rotation.

Hydraulic motor for excavator

(3) In addition to the inlet and outlet of the hydraulic motor, there are separate oil leakage ports;

Hydraulic pump is generally only in and out of the oil port (except axial piston pump), the leakage of oil and oil inlet are connected.

(4) The volume efficiency of the hydraulic motor is lower than that of the hydraulic pump.

(5) Usually hydraulic pump working speed is relatively high, and the hydraulic motor output speed is low.

In addition, the gear pump suction mouth big, small, and gear hydraulic motor suction, discharge mouth size is the same.

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