The propellors are typically fitting on to a coned tail shaft. The equally coned propellor hub is hydraulically opened and pushed on to the propellor cone. When the hydraulic pressure is released the propellor shrinks on the tail shaft and grips it. The friction between the two components causes the propellor to rotate in line with tail shaft rotation. A propellor nut is also employed to axially locate the propellor and prevent loss of friction. Propellor removal is the reverse.