Intermediate bearings, also known as tunnel bearings, are a type of bearing used in mechanical engineering to support the rotational motion of intermediate shafts, mainly used in ship shaft systems and transmission systems. This bearing is divided into two types: sliding and rolling. Sliding structures are commonly used in the marine industry, with the body cast from steel or cast iron and the base fixed by through bolts . Common classifications include three pull rod type (SL type), three channel steel and three bearing shell type (SC type), etc The intermediate bearing plays a role in compensating for axial/angular installation errors and buffering engine runout loads in the transmission system. It is usually composed of a bearing body and elastic elements (such as rubber sleeves). When applied to ships, the radial load generated by the self weight and deformation of the shaft system is required, and its lubrication performance is directly related to the shaft neck speed and lubricating oil temperature: an increase in speed leads to an increase in oil film thickness but synchronous increase in friction power consumption, while an increase in temperature reduces the friction coefficient and power consumption . Typical products such as Simplex intermediate shaft bearings adopt a short sliding structure design, equipped with temperature monitoring and cooling systems, which can achieve precise centering and avoid edge loads . Optimizing the structural parameters of bearings can effectively reduce frictional resistance, vibration noise, and extend their service life .
