+86-576-86837168

News

We can meet the needs of different customers with different purchase quantity.

The tractor hydraulic pump is a device that converts mechanical energy into liquid pressure energy and provides pressurized liquid for the tractor hydraulic system. It belongs to a positive displacement pump, and its basic principle is the volume change of the closed oil chamber. When the volume of the closed oil chamber in the pump expands, it will absorb oil, and if it shrinks, it will squeeze out and force the oil to overcome the resistance and output to the outside.

The volume of oil discharged by the hydraulic pump for one revolution is displacement. Quantitative pumps have a fixed displacement, while variable displacement pumps are variable. The oil delivery volume of the hydraulic pump per unit time is the flow rate, and the flow rate is the product of the displacement and the speed of the hydraulic pump. The product of the pressure difference between the inlet and outlet of the hydraulic pump and the flow rate is the hydraulic power output by the hydraulic pump.

Hydraulic pumps can be divided into gear pumps, rotor pumps, sliding vane pumps, and plunger pumps according to their structure.

gear pump

For the quantitative pump. Commonly used external gear pumps consist of a pair of involute cylindrical spur gears. The tooth top of the gear and the inner cavity of the housing, as well as the end surface of the gear and the side wall of the housing, serve as radial and axial sealing surfaces respectively, so that a closed oil chamber is formed between the teeth. The meshing point M separates the meshing teeth into left and right oil chambers. When the gear rotates in the direction shown in the figure, the teeth of the right chamber withdraw from meshing, and the volume expands to become an oil suction chamber; the left chamber enters meshing, and the volume shrinks to become an oil pressure chamber.

In order to reduce the leakage of the end face of the high-pressure gear pump, the front and rear bushings are axially floating. The high-pressure oil on the oil outlet channel is led to the back of the bushing, and the bushing is pressed against the end face of the gear. The pressing force is directly proportional to the oil outlet pressure of the hydraulic pump, which can reduce the end-face leakage caused by the pressure rise. External gear pumps are simple in structure, low in cost, small in size, and light in weight, and are the most widely used medium and high-pressure hydraulic pumps on tractors and agricultural machinery.

Rotor pump

It consists of an inner rotor (driver) with a short epicycloid equidistant curve tooth shape and an outer rotor (driven) with an arc tooth shape. The number of teeth of the inner and outer rotors differs by one tooth, and each rotates around two centers with eccentricity e in the same direction. When rotating, the meshing point changes position, forming various closed oil chambers with variable volumes. The chambers on the right side suck oil; the left side drains oil. Every time the inner rotor rotates one revolution, each oil chamber completes oil suction and oil discharge once. Rotor pumps are often used as medium and low-pressure hydraulic pumps.

Sliding vane pump

It is mainly composed of a rotor, a stator, and a sliding vane that slides radially in the vane groove of the stator. The offset of the rotor forms annular passages of unequal width in the stator, which are separated into closed oil chambers of unequal volume by sliding vanes. When the rotor rotates with the sliding vane, the sliding vane keeps in contact with the inner wall of the stator under the action of centrifugal force. The volume of each oil chamber changes with the rotor to complete oil absorption and oil discharge. Sliding vane pumps are commonly used as medium and low-pressure hydraulic pumps.

plunger pump

The volume change is achieved by the reciprocating movement of the plunger. The plunger and the plunger hole are easy to precisely machined, have good sealing performance, and can maintain high volumetric efficiency under high pressure. According to the arrangement of the plunger, the plunger pump can be divided into two types: axial type and radial type.

axial piston pump

The structure and working principle are shown. The cylinder body is rotated by the drive shaft, and the plunger in the cylinder body is reciprocated by the swash plate. Half of the plunger enters the oil, and the other half exits the oil, and the incoming and outgoing oil is collected or distributed by the distribution plate respectively. Changing the slant angle γ of the swash plate can change the displacement. There is relative sliding between the plunger end and the swash plate, and sliding shoes are installed therebetween. The shoe guides the high-pressure oil in the plunger to the bottom, and the hydraulic pressure pads the shoe to make it statically balanced, and the oil film reduces wear and improves mechanical efficiency. Axial piston pump has small unit power and weight, but its structure is relatively complex, and its operation and maintenance requirements are strict. It is often used in closed-center hydraulic systems with pressure-flow compensation on high-power tractors.

radial piston pump

Each plunger is arranged in the same plane perpendicular to the axis, and the eccentric wheel pushes the plunger to press oil. The return stroke of the plunger is pressed against the eccentric wheel by the spring. Each plunger has a check valve for oil in and out. When the outlet oil pressure is very low, the eccentric wheel chamber communicates with the oil inlet passage. The plunger is close to the eccentric wheel, and the stroke is 2e; when the outlet oil pressure reaches the working pressure, the pressure is transmitted to the eccentric wheel chamber through the control valve and acts on the bottom of the plunger, and the plunger is kept at the bottom hydraulic pressure and the return spring compression force In the balanced position, the contact with the eccentric wheel is broken away, the actual stroke decreases and the corresponding displacement decreases. Therefore, this pump can achieve a large flow change within a range of small pressure changes, and it is a constant pressure variable pump. This pump is used in the constant pressure closed center hydraulic system on large and medium power tractors.

DAYE is a professional supplier of agricultural machinery hydraulic pumps. For more professional information, please continue to follow us.