Shaft Collars
The Shaft Collars is a cylindrical mechanical part that is placed on the Cast Iron rotating shaft and can be an integral area of the sliding bearing.
Generally, the Shaft Collars and the bearing casing have an interference in shape and a clearance fit with the shaft.

1, concept

A sleeve made of a complete 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 group of robot components, the sleeves are particularly 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 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 elements that fix and reduce the coefficient of friction of the load during mechanical transmission.
The similarity between your Shaft Collars and the bearing is that both bear the strain of the shaft.
The difference between the two is that the sleeve is of integral structure, and the relative movement between your shaft and the sleeve is when rotating; and the bearing is split, and the rotation is the relative motion of the inner and outer bands of the bearing itself. But in essence, the Shaft Collars is truly a kind of sliding bearing.

3, common factors behind damage

During the long-term procedure of the Shaft Collars, the top of journal is subjected to the pressing drive of the expansion sleeve and the composite mechanical drive, which will cause its permanent deformation, and the diameter may be reduced by 0.1mm~0.3mm. Because of this, the mechanical expansion and the strength of the force are not 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

Due to the large worth of components, the traditional repair methods are relatively expensive. With the advancement of advanced technology such as for example polymer composite materials abroad, some repair strategies with quick fix and low cost are favored. This method has also been presented in China, and the older Fushun Blue 2211F materials. The material gets the comprehensive mechanical properties, exceptional adhesion and heat and corrosion level of resistance which cannot be compared with the traditional method. The maximum compressive power can reach 1200kg/cm2, and the adhesion (overlap shear tensile test) is 225kg on the smooth steel surface area. /cm2. Therefore, it can be used for the repair of wear of large Shaft Collars parts. Furthermore, the equipment doesn’t need to be disassembled in a big level, which saves a lot of manpower and materials resources for the enterprise.