Techdrives says that the ETP Hyloc bush is a unique design based on hydromechanical principles, which delivers significant advantages for the assembly and disassembly of hubs to shafts. It eliminates problems associated with sticking and fretting, plus there are reductions in installation time. Hyloc bushes replace keyways that can have problems associated with fitting, backlash and fretting. In addition, Hyloc bushes can also also replace taper connections that can be difficult to release and can be prone to damage from dirt contamination. Being self-contained, each Hyloc bush creates a backlash-free shaft connection that is easy to adjust, fast to fix, and quick to release.
Hyloc locking bushes are available from Techdrives in a standard range for shafts from 50-220mm. Customised models can be supplied for larger shafts. Connections can be made to gears, rolls, turbine impellers and other types of hub using surfaces that are machined parallel and to standard tolerances. Hyloc works using hydraulic pressure from a hand or electric pump. It consists of a double-walled sleeve that encloses a tapered piston, which moves axially under the hydraulic pressure. Connection ports enable the piston to be driven into the sleeve, which forces the walls outwards to create a friction fit between the shaft and the hub. When the pressure is removed, the piston locks mechanically, forming a secure joint with very high radial load capacity. The bush is released by applying pressure to ports that connect to the opposite end of the piston, thereby forcing it back down the sleeve to relieve the friction fit. The whole process is said to be fast, easy and clean compared to alternatives of keyways and taper joints.
Hyloc bushes are used in rolling mills, water turbines, feed rolls and dynamometers. The common factor is the need to save time on disassembly. Torque ratings are particularly high - for example, 30kNm on a 100mm shaft - and the torque is proportional to the mounting pressure, so it can be adjusted. Normally bushes are set at 1000bar, but anywhere in a range 800-1200bar is possible. During assembly it is easy to adjust and precisely position the hub both radically and axially. Once set, the Hyloc coupling has excellent concentricity, with run-out values of 0.01-0.02mm, which is adequate for connecting gears to gearbox shafts.
Hyloc locking bushes are manufactured by ETP and are available in the UK through Techdrives. Links from the product page lead to a simple animation video showing a Hyloc bush in operation. Follow the link for more information about ETP Hyloc locking bushes.