Hydraulic belt tensioning units represent a solution for multiribbed belt drives subject to very high requirements. They consist of a hydraulic element with an integrated compression spring and hydraulic leakage gap damping together with the lever arm with a mounted tension pulley. The hydraulic leakage gap damping acts in a controlled manner and proportional to the speed so that damping is only generated when it is needed. The belt preload force required is matched to the specific application by means of the integral compression ratio and the lever ratio. The damping required is adjusted through the selection of the leakage gap. The characteristics of the hydraulic oil used ensure the lowest possible temperature dependence of the damping in conjunction with excellent ageing resistance - with practically no wear.

The tension pulleys fitted consist of single or double row ball bearings developed specially by INA for belt drive applications with, depending on the application, pulleys made from glass fibre-reinforced polyamide or corrosion-resistant steel.

The pulleys made from polyamide resistant to high temperatures are, due to the highly developed tooling and production technology, equal in terms of roundness and running characteristics to the steel pulleys used as an alternative.