Thickness Distribution of Low Stress Three-Layer Bearing for Cam Lobe Hydraulic Motor

When the working speed of the low-speed high-torque cam lobe hydraulic motor is developing towards an extremely low speed (up to 0.2 r/min), one of its core friction pairs, the roller-piston pair, is difficult to establish a hydrodynamic lubricating oil film at low speeds, leading to wear fail of the friction pair. Therefore, a three-layer bearing bush structure of steel back-copper powder-self-lubricating material was usually arranged between the roller-piston pair to improve the lubrication ability of friction pair at low speed. However, the cam lobe motors usually need to withstand large loads, and how to design three-layer bearing with high bearing capacity has become a challenge in the design of cam lobe hydraulic motors. The thickness distribution of each layer of the three-layer bearing directly affects the maximum stress of the bearing under load, and then affects the bearing capacity and service life of the cam lobe hydraulic motor. In order to explore the effect of the thickness of each layer of the three-layer bearing bush on the overall bearing capacity of the bearing bush, this paper carried out the force analysis of the three-layer bearing bush, and obtained the mapping law between the thickness of the three-layer material and the maximum von Mises stress of the self-lubricating layer. And this paper also proposed a low-stress three-layer self-lubricating bearing bush thickness distribution scheme suitable for the roller-piston pair of cam lobe motors and designed a three-layer bearing thickness distribution scheme (the self-lubricating layer thickness was 0.2 mm, the copper powder layer thickness was 0.3 mm, and the steel back layer thickness was 1.0 mm) for an cam lobe hydraulic motor with a maximum working pressure of 31.5 MPa. The three-layer bearing using this scheme was installed on the hydraulic motor for motor performance testing. The test results show that the bearing capacity of the bearing under the thickness distribution can meet the requirements of the maximum working pressure of the cam lobe motor.