Shaft Collars
The Shaft Collars is a cylindrical mechanical part that is placed on the rotating shaft and can be an integral part of the sliding bearing.
In general, 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 called a Shaft Collar.
The bearing shell is equivalent to the outer ring of the sliding bearing, the sleeve is integral and the opposite shaft is moving, as the bearing shell is segmented and the opposite shaft is rotating.
In the LEGOMindstorms series and BioTransRoSys group 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 sorts of Shaft Collarss on the main 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 (known as “shafts” in Japan) are parts 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 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 movement 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 operation of the Shaft Collars, the top of Universal joint journal is put through the pressing drive of the growth sleeve and the composite mechanical drive, which will cause its long term deformation, and the diameter could be reduced by 0.1mm~0.3mm. Because of this, the mechanical expansion and the strength of the force aren’t up to the mandatory tightening push, and a complementing gap occurs between the sleeve and the main shaft, causing use of the sleeve.

4, the most recent repair method

Because of the large worth of components, the original repair strategies are relatively expensive. With the development of advanced systems such as for example polymer composite materials abroad, some repair methods with quick restoration and low priced are favored. This technique has also been presented in China, and the older Fushun Blue 2211F materials. The material has the comprehensive mechanical properties, exceptional adhesion and temperatures and corrosion level of resistance which cannot be compared with the original method. The utmost compressive power can reach 1200kg/cm2, and the adhesion (overlap shear tensile check) can be 225kg on the smooth steel surface area. /cm2. Therefore, it can be used for the fix of wear of large Shaft Collars parts. Moreover, the equipment doesn’t need to be disassembled in a sizable scale, which saves a whole lot of manpower and material resources for the business.