Abstract: An energy recovering system of a hydraulic lift device for a battery operated industrial truck. With the system, working oil can be supplied to other hydraulic actuators while energy recovering operation is performed by the hydraulic lift device, and energy recovering efficiency is increased. A hydraulic motor (6) is disposed in a fluid path for recovering pressurized working fluid from a lift cylinder (1) via a control valve (10) to a working fluid reservoir tank (8) so that the hydraulic motor (6) is driven by the pressurized working fluid returning from the lift cylinder (1). The hydraulic motor (6) is connected to an electric motor (4) for driving a hydraulic pump (3), which supplies pressurized fluid to the lift cylinder (1), by means of a one-way clutch (7) which performs torque transmission only from the hydraulic motor (6) to the electric motor (4).

Abstract: The hydraulic system includes a hydraulic pump for supplying hydraulic oil to a hydraulic actuator, an electric motor for driving the hydraulic pump, hydraulic pipes provided between the hydraulic actuator and a tank, a hydraulic motor provided in one of the hydraulic pipes for recovering the hydraulic oil and adapted to be driven on receipt of the hydraulic oil which has been recovered from the hydraulic actuator, a drive transmitting device connected to both the hydraulic motor and the electric motor for transmitting driving torque from the hydraulic motor to the electric motor, and a control unit which conducts regenerative control of the electric motor according to rotation number of the electric motor, when the electric motor is driven by the hydraulic motor.