Sliding bearings are bearings that operate under sliding friction. Sliding bearings work smoothly, reliably, and without noise. Under liquid lubrication conditions, the sliding surface is separated by lubricating oil without direct contact, which can greatly reduce friction loss and surface wear. The oil film also has a certain ability to absorb vibrations. But the starting friction resistance is relatively high. The part of the shaft supported by bearings is called the journal, and the parts that match the journal are called the bearing shells. The anti friction material layer cast on the inner surface of the bearing shell to improve its friction properties is called a bearing liner. The materials of bearing shells and bearing liners are collectively referred to as sliding bearing materials. The application of sliding bearings is generally under low-speed and heavy-duty working conditions, or in operating parts where maintenance and lubrication are difficult