Shaft Collars
The Shaft Collars is a cylindrical mechanical part that’s placed on the rotating shaft and can be an integral area of the sliding bearing.
In general, the Shaft Collars and the bearing housing have an interference fit 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 the same as the outer 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 split into full sleeves and 1/2 sleeves.
The primary materials of all kinds of Shaft Collarss on the main hydropower producing units are ZQAl9-4, ZQSn10-1 and Electric Motors 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 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 the shaft and the sleeve is when rotating; and the bearing is definitely split, and the rotation is the relative movement of the inner and outer rings of the bearing itself. However in essence, the Shaft Collars is actually a kind of sliding bearing.
3, common causes of damage
During the long-term operation of the Shaft Collars, the surface of the journal is subjected to the pressing power of the expansion sleeve and the composite mechanical drive, that may cause its permanent deformation, and the diameter could be reduced by 0.1mm~0.3mm. As a result, the mechanical expansion and the effectiveness of 
the force aren’t up to the required tightening push, and a matching gap occurs between your sleeve and the main shaft, causing use of the sleeve.
4, the most recent repair method
Due to the large value of components, the traditional repair methods are relatively expensive. With the development of advanced technology such as polymer composite materials abroad, some repair methods with quick fix and low priced are favored. This method has also been launched in China, and the older Fushun Blue 2211F components. The material gets the extensive mechanical properties, excellent adhesion and temp and corrosion level of resistance which can’t be compared with the original method. The maximum compressive strength can reach 1200kg/cm2, and the adhesion (overlap shear tensile check) is normally 225kg on the smooth steel surface area. /cm2. As a result, it can be utilized for the repair of wear of huge Shaft Collars parts. Furthermore, the equipment doesn’t need to end up being disassembled in a huge level, which saves a lot of manpower and material resources for the business.