Why Does the Fixed Rotor Pair of a Hydraulic Press Cycloidal Motor Rotate in Reverse?

The fixed rotor itself is correct; the issue lies in the incorrect relative position between the rotor and the port plate. Cycloidal motors are divided into two types based on oil distribution methods: shaft oil distribution and end face oil distribution.

1. Shaft Oil Distribution Type

The oil distribution mechanism of this type is located on the main shaft. You can make a mark on the end cover aligned with an oil groove, and align this mark with the minimum sealed cavity of the fixed rotor pair for testing. If the motor rotates in reverse, simply adjust it by one more tooth (i.e., misalign by one additional tooth) to fix the issue.

2. End Face Oil Distribution Type

The oil distribution mechanism here is the port plate, which is connected to the rotor via the oil distribution shaft. After installing the fixed rotor pair properly, measure the depth of the sealed cavity. If the clockwise cavity of the minimum sealed cavity is deeper than the counterclockwise cavity, the motor will rotate forward; otherwise, it will rotate in reverse.

The total depth of the cavity is the sum of the thicknesses of the fixed rotor, baffle, and port plate.

Key Cause of Reverse Rotation in Swing Motors

The main reason for reverse rotation in swing motors lies in the port plate. Generally speaking, when the port plate feeds oil from the side, and the oil is just directed to the clockwise-side cavity (high-pressure cavity) of the minimum sealed cavity of the fixed rotor pair, the motor will rotate forward.