Hydraulic shrink discs

Hydraulically tensionable shrink discs are used when shaft and hub have to be connected safely and quickly. They are particularly suitable for assembly on test benches and repetitive clamping operations. Furthermore, the SHS series impresses with its unique selling points, such as low pressure required for clamping, customer-side performance of maintenance and repair work, and the possibility of adapting the inner ring to different sizes.

The main function of a hydraulically tensionable shrink disc is therefore to securely connect a shaft to a hub by means of a frictional connection. For example, between a drive shaft and a hollow transmission shaft.

The hydraulically tensionable shrink disc creates a backlash-free connection by pressing the hub onto the shaft. This type of connection is mainly used to transmit torque. The shrink disc of the "SHS" series only provides the required forces and does not itself transmit any forces or torques between the shaft and hub. It is therefore not in the flow of forces. In the SHS, the basic principle of the mechanical, three-part shrink disc has been retained. This principle has been tried and tested for a long time. Here, the force-transmitting friction surfaces are strictly separated from the hydraulic system. This strict separation prevents oil contamination of these surfaces.

The biggest advantage of the hydraulic tensionable shrink disc like the SHS series is the enormous time saving during assembly. This system can already be clamped with low pressure between 120 bar and 200 bar and thus reduces the assembly times considerably. The reduction of this time increases exponentially with the diameter. For larger diameters, e.g. 530 mm, a hydraulically tensionable shrink disc of the "SHS" type is already tensioned after a few minutes.

This compares with an assembly time of several hours for a mechanical shrink disc. The time required and the physical strain on fitters and maintenance personnel can therefore be significantly reduced. Even after a long service life of several years, when, for example, seals no longer function depending on their location, the hydraulically tensionable shrink disc of the "SHS" series can be dismantled in the same way as a mechanical shrink disc. This is done by loosening the screw connection and without further pressure application.

It is installed by sliding the shrink disc onto the hollow shaft and the subsequent tightening of the hydraulik system. By using conical surfaces the inner diameter reduces and the radial pressure is built up. After clamping the SHS will be locked mechanically and the hydraulic pressure will be removed. Due to this simple approach the SHS is suitable for repetitive clamping operations as they occur on a test bench, for example.

To achieve proper operation and to a sufficiently high coefficient of friction, the contact surfaces between shaft and hub must be free of grease, dry and clean. The functional surfaces of the shrink disc are equipped at the factory with lubricant. The contact surfaces between the hub and shrink disc must also be provided with grease before installation.