Shaft Collars
The Shaft Sprial Gearboxes Collars is a cylindrical mechanical part that’s 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 fit and a clearance match 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 specifically 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 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 parts that fix and reduce the coefficient of friction of the strain during mechanical transmission.
The similarity between the 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 usually split, and the rotation is the relative movement of the internal and outer rings of the bearing itself. However in essence, the Shaft Collars is actually a sort 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 long term 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 pressure, and a matching gap occurs between 
your 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 development of advanced systems such as polymer composite materials abroad, some repair methods with quick restoration and low priced are favored. This technique has also been launched in China, and the older Fushun Blue 2211F components. The material gets the comprehensive mechanical properties, excellent adhesion and temp and corrosion level of resistance which can’t be compared with the traditional method. The maximum compressive strength can reach 1200kg/cm2, and the adhesion (overlap shear tensile check) is 225kg on the smooth steel surface. /cm2. As a result, it can be used for the repair of wear of huge Shaft Collars parts. Moreover, the equipment doesn’t need to become disassembled in a huge level, which saves a lot of manpower and material resources for the enterprise.