The main part (see structure profile) is driven by the drive shaft to rotate the cylinder block, so that the seven plungers evenly distributed on the cylinder block rotate around the center line of the drive shaft, and the slide shoe in the column slide assembly is pressed against the variable head (or swash plate) through the center spring. In this way, the plunger reciprocates with the rotation of the cylinder block to complete the oil absorption and oil pressure action.

The output variable of the MXB pump is achieved by maneuvering or manual method, using the high-pressure oil output by the main part in the work to manipulate the servo variable mechanism to achieve the purpose of variable. The variable head can be tilted up and down, so the oil flow in the work can be reversed.

The principle of variable is as follows: The high-pressure oil extracted from the oil outlet of the pump body enters the lower cavity a of the variable housing through the flow channel in the pump body and the pump shell. When the pull rod moves down, push the servo valve core to move down, then the high-pressure oil in cavity a enters the upper cavity c through channel b, pushes the variable piston to move down, drives the pin, and makes the variable head rotate around the center, so that the Angle changes and the flow rate changes; When the pull rod is lifted upward, channel b is closed, and the high pressure oil in the upper cavity c is relieved through channel d, and the resulting pressure difference makes the variable piston move upward, thereby realising the variable.