Shaft Collars
The Shaft Collars is a cylindrical mechanical part that is positioned on the rotating shaft and is an integral part of the sliding bearing.
Generally, the Shaft Collars and the bearing housing have an interference in shape and a clearance fit with the shaft.
1, concept
A sleeve made of a full cylindrical protective shaft is named a Shaft Collar.
The bearing shell is equivalent to the external ring of the sliding bearing, the sleeve is integral and the contrary shaft is moving, as the bearing shell is segmented and the contrary shaft is rotating.
In the LEGOMindstorms series and BioTransRoSys series of robot components, the sleeves are particularly referred to as the silver-gray LEGO standard shaft holders, which are split into full sleeves and 1/2 sleeves.
The main materials of all types of Shaft Collarss on the main hydropower generating units are ZQAl9-4, ZQSn10-1 and ZQSn6-6-3.
2, the difference
A Shaft Collars is a sleeve on a propeller shaft or a yoke shaft. Bearings (referred to as “shafts” in Japan) are components that fix and decrease the coefficient of friction of the strain during mechanical transmission.
The similarity between the Shaft Collars and the bearing is that both bear the load of the 
shaft.
The difference between your two is that the sleeve is of integral structure, and the relative movement between the shaft and the sleeve is when rotating; and the bearing is definitely split, and the rotation is the relative motion of the internal and outer bands of the bearing Taper Lock Pulley itself. However in essence, the Shaft Collars is actually a sort of sliding bearing.
3, common factors behind damage
During the long-term procedure of the Shaft Collars, the surface of the journal is put through the pressing push of the growth sleeve and the composite mechanical drive, which will cause its long lasting deformation, and the diameter could be reduced by 0.1mm~0.3mm. Consequently, the mechanical expansion and the effectiveness of the force aren’t up to the required tightening drive, and a complementing gap occurs between the sleeve and the main shaft, causing use of the sleeve.
4, the latest repair method
Because of the large worth of components, the traditional repair methods are relatively expensive. With the development of advanced technologies such as polymer composite materials overseas, some repair methods with quick fix and low cost are favored. This technique has also been introduced in China, and the older Fushun Blue 2211F materials. The material gets the comprehensive mechanical properties, excellent adhesion and heat and corrosion resistance which cannot be compared with the original method. The utmost compressive strength can reach 1200kg/cm2, and the adhesion (overlap shear tensile test) is usually 225kg on the smooth steel surface. /cm2. As a result, it can be utilized for the restoration of wear of large Shaft Collars parts. Moreover, the equipment does not need to become disassembled in a huge level, which saves a lot of manpower and material resources for the enterprise.