Patent ID: 6543223
Filing Date: 2003-04-08
Classification: B25B,F15B

Abstract:
A drive device comprising a closed hydraulic circuit, which includes a hydraulic drive able to be actuated by hydraulic medium and a hydraulic pump causing the supply and removal of such hydraulic medium in relation to the hydraulic drive, and furthermore an electric motor for operation of the hydraulic pump, activation of the hydraulic drive being dependent on the operational state of the hydraulic pump;wherein said hydraulic drive includes at least one drive piston drivingly coupled with a force output part, said drive piston dividing two working chambers in a fluid tight manner from one another, said working chambers being connected by way of a respective hydraulic circuit with the hydraulic pump, the supply of hydraulic fluid to the one working chamber taking place with the simultaneous escape of hydraulic fluid from the other working chamber; and wherein said two hydraulic circuits comprise an overridable check valve, which normally allows flow of fluid from the hydraulic pump to the hydraulic drive and prevents flow in the opposite direction, each check valve being able to be overridden by a pressure maintained in the respectively other hydraulic circuit by the hydraulic pump in order to render possible fluid flow from the hydraulic drive back to the hydraulic pump.