A typical example of this are shaft-hub connections that permit compact design of the power train, high bending torques as well as strong radial loads, and facilitate the installation and dismantling of gears and/or motors. Conventional connecting components only meet these requirements to a certain extent. There are several reasons for this: the traditional positive-locking feather key connection, which always shows a certain backlash owing to its design, can quickly wear in such drives when exposed to the typical alternating stresses. Splined shafts that demand considerable manufacturing effort also have to be regarded critically in this application.
Leading suppliers, e.g. of conveyor systems, crushers and mixers, therefore use a special design of frictional connections known under the name shrink discs. As these shaft-hub connections are installed outside the power train, they are not exposed to dynamic forces even at high drive loads. That increases the lifetime and reliability of the power train.
In their simplest form, the shrink discs (Figure 1) consist of one inside ring and one outside ring with opposing conical surfaces. As a result of axial displacement (mechanical or hydraulic) of the outer ring against the inner ring, the hub is pressed onto the shaft. On account of the surface pressure, a backlash-free, dirt-resistant connection results that does not allow any crevice corrosion.
In contrast to thermally or otherwise joined friction-type connections, Stüwe frictional connections (Figure 2) can be easily installed and, if necessary, disassembled non-destructively and reused. The clearance fits between shaft or shaft-hub and shrink disc simplify assembly and maintenance. The shrink discs are resilient to knocks and impacts and the shafts and hubs can have normal surface finishes.