Talking about the hydraulic drive motor of crawler excavator

Anyone who knows about the excavator knows that the excavator's walking and work are done by hydraulic pressure. Some people may ask, and also walk with the crawler, why the tank can go so fast, and the excavator can only Go slowly?

This is the difference between the power output system. The tank is mechanically rigidly connected. Like the driving method of the car, the gearbox is switched by the gearbox to coordinate the relationship between power and speed, and the excavator is driven by hydraulic drive. It is not that the hydraulic drive will be slower than the mechanical drive, but it is determined by the work demand. The so-called demand determines the production. The excavator does not need high travel speed when moving, but requires a large driving force, so the excavator uses the column. Plug-type drive motor, the biggest feature of this final drive motor is the output of low speed and high torque.

Hydraulic drive motors are generally classified into gear type, vane type, plunger type and other forms. Since the excavator is a plunger type, the motor and the pump are in principle reversible because they work in the same principle, but only energy conversion. The direction is different. For example, electric motors and generators, the principle is electromagnetic induction, the motor is to convert electrical energy into mechanical energy, and the generator converts mechanical energy into electrical energy. A hydraulic pump is a device that converts mechanical energy into potential energy, and a hydraulic drive motor is a device that converts potential energy into mechanical energy.

The plunger hydraulic final drive motor is further divided into an axial piston type and a radial piston type.

The working principle of the radial piston type hydraulic motor, when the pressure oil enters the bottom of the plunger in the cylinder through the window of the fixed oil distribution shaft, the plunger protrudes outwardly and tightly against the inner wall of the stator, due to the stator and the cylinder There is an eccentric moment in the body. At the point where the plunger is in contact with the stator, the stator has a reaction to the plunger. When the oil pressure acting on the bottom of the plunger is p, the plunger diameter is d, and the angle between the force and the force is X, the force generates a torque to the cylinder to rotate the cylinder. The cylinder body is further outputted by the end face of the drive shaft to output torque and speed.

Axial plunger

The working principle of the axial piston motor is that the oil distribution plate and the swash plate are fixed, and the motor shaft is rotated together with the cylinder body. When the pressure oil enters the plunger hole of the cylinder through the window of the oil distribution plate, the plunger protrudes under the action of the pressure oil, and the swash plate of the swash plate generates a normal reaction force to the plunger, and the force can be decomposed into the shaft. Dividing force and vertical force. The vertical component is balanced with the hydraulic pressure on the plunger, and the vertical component causes the plunger to generate a torque to the center of the cylinder, which drives the motor shaft to rotate counterclockwise. The instantaneous total torque produced by the axial piston motor is pulsating. If the motor pressure oil input direction is changed, the motor shaft rotates clockwise. The greater the inclination of the swashplate, the greater the torque generated and the lower the rotational speed.

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