In the Hydro system a layer of grease between two hardened steel sleeves transmits the pressure and permits their expansion towards the spindle and the tool so the error of centring is eliminated.
![](https://www.gdatools.it/wp-content/uploads/2021/02/hy1.png)
![](https://www.gdatools.it/wp-content/uploads/2021/02/hy2.png)
In the Hydro system a layer of grease between two hardened steel sleeves transmits the pressure and permits their expansion towards the spindle and the tool so the error of centring is eliminated.