Patent ID: 8851260

Claim:
A positive locking clutch comprising: a hydraulically or pneumatically operable piston comprising a first pressure chamber configured to hold a pressure medium within; a gear with gear teeth; a counter gear with counter gear teeth and counter gear gaps configured to interlock with the gear teeth of the gear with minimal gear spacing when the clutch is in an engaged state; a mechanical pre-loading device configured to apply a pre-loading force upon the gear in the direction of engagement with the counter gear when the piston is actuated and the gear teeth abut the counter gear teeth in a tooth-to-tooth position; wherein the clutch enters the engaged state by acceleration of the gear in the direction of the counter gear due to the pre-loading force when the gear teeth of the gear meet the counter gear gaps during relative rotation of the gear and counter gear; wherein the mechanical pre-loading device comprises a first spring arranged between the piston and the gear, wherein the first spring is configured to push the piston and gear apart; a return device configured to return the gear to a default state when the piston is not pressurized, wherein the return device comprises a second pressure chamber configured to return the gear to the default state through the building up of counter pressure actuating the piston when the piston is not pressurized.