Shaft Collars
The Shaft Collars is a cylindrical Torque Arm mechanical part that is placed on the rotating shaft and is an integral part of the sliding bearing.
In general, 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 called a Shaft Collar.
The bearing shell is equivalent to 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 contrary shaft is rotating.
In the LEGOMindstorms series and BioTransRoSys group of robot components, the sleeves are specifically known as the silver-gray LEGO regular shaft holders, which are divided into full sleeves and 1/2 sleeves.
The primary 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 (known as “shafts” in Japan) are elements that fix and decrease the coefficient of friction of the load during mechanical transmission.
The similarity between your 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 is certainly split, and the rotation is the relative motion of the internal and outer rings of the bearing itself. However in essence, the Shaft Collars is truly a kind of sliding bearing.

3, common factors behind damage

During the long-term operation of the Shaft Collars, the top of journal is subjected to the pressing drive of the growth sleeve and the composite mechanical push, which will cause its long term deformation, and the size could be reduced by 0.1mm~0.3mm. Consequently, the mechanical expansion and the strength of the force are not up to the required tightening push, 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 value of components, the traditional repair methods are relatively expensive. With the development of advanced technology such as polymer composite materials overseas, some repair strategies with quick repair and low cost are favored. This technique has also been launched in China, and the more mature Fushun Blue 2211F components. The material gets the comprehensive mechanical properties, superb adhesion and heat range and corrosion level of resistance which can’t be compared with the original method. The utmost compressive strength can reach 1200kg/cm2, and the adhesion (overlap shear tensile check) is definitely 225kg on the smooth steel surface area. /cm2. Therefore, it can be utilized for the repair of wear of large Shaft Collars parts. Moreover, the equipment doesn’t need to become disassembled in a sizable level, which saves a whole lot of manpower and materials resources for the business.