Abstract: The present invention relates to a ship's drive having a transmission which is arranged between the engine and the propeller which has hydraulically controllable, and optionally actuatable forward and reverse clutches, as well as a trolling device provided with a pressure reduction valve. In order to create a ship's drive which has a trolling device and, by simple means and at little expense, which prevents destruction of the clutches as a result of erroneous operation and permits reliable maneuvering of a ship in every condition of operation of the trolling device, the pressure-reduction valve of the trolling device has an electro-hydraulic control unit and that, between the pressure reduction valve and at least one of the clutches, a valve is arranged which is hydraulically in communication with the pressure reduction valve and is connected to the pressurized oil line. A non-return valve is arranged between a feed line to the clutch and a rapid-vent line.

Abstract: Two hydraulic brakes or clutches being primary users, are alternately, delayedly, hydraulically energized from a constant volumetric flow rate pump feeding also a secondary user via a pressure controller with a differential piston operated by feedback ducts from the primary users via a throttle valve. The latter valve is bypassed through a check valve for undelayed de-energization. A selector valve is disposed between the branch point for the secondary user and upstream as to energizing fluid from the feedback connection to the primary user. The pressure controller is described further as to several structural details.