Shaft Collars
The Shaft Collars is a cylindrical mechanical part that’s 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 the same as the external ring of the sliding bearing, the sleeve is integral and the opposite shaft is moving, while the bearing shell is segmented and the opposite shaft is rotating.
In the LEGOMindstorms series and 
BioTransRoSys group of robot components, the sleeves are specifically referred to as the silver-gray LEGO regular shaft holders, which are divided into full sleeves and 1/2 sleeves.
The main materials of all sorts of Shaft Collarss on the major hydropower producing 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 parts that fix and decrease the coefficient of friction of the load during mechanical transmission.
The similarity between the Shaft Collars and the bearing is that both bear the load of the shaft.
The difference between the 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 can be split, and the rotation may be the relative motion of the internal and outer rings of the bearing itself. But 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 top of journal is put through the pressing power of the growth sleeve and the composite mechanical force, that may cause its long lasting deformation, and the diameter may be reduced by 0.1mm~0.3mm. Because of this, the mechanical expansion and the strength of the force aren’t up to the required tightening power, and a coordinating gap occurs between the sleeve and the primary shaft, causing put on of the sleeve.
4, the most recent repair method
Because of the large worth of components, the original repair methods are relatively expensive. With the advancement of advanced technologies such as polymer composite materials overseas, some repair methods with quick restoration and low priced are favored. This method has also been presented in China, and the more mature Fushun Blue 2211F components. The material gets the comprehensive mechanical properties, excellent adhesion and temperatures and corrosion resistance which cannot be compared with the traditional method. The maximum compressive power can reach 1200kg/cm2, and the adhesion (overlap shear tensile check) is normally 225kg on the smooth steel surface area. /cm2. Therefore, it can be utilized for the restoration of wear of huge Shaft Collars parts. Moreover, the equipment doesn’t need to become Reciprocating Vacuum Pump disassembled in a sizable level, which saves a lot of manpower and materials resources for the enterprise.