Provided is a hydraulic driving apparatus including a calculation section calculating a temporary target engine rotation speed corresponding to an engine operation amount, a calculation section calculating a temporary target pump displacement volume based on first-control and second-control target pump displacement volumes corresponding to an actuator operation amount and a pump load pressure, and a command section calculating a final target engine rotation speed and a final target pump displacement volume to output commands. The command section calculates a target pump discharge amount from the temporary target engine rotation speed and the temporary target pump displacement volume, sets the final target pump displacement volume to one larger than the temporary target pump displacement volume, and sets the final target engine rotation speed to one being lower than the temporary target engine rotation speed and allowing a pump discharge amount equivalent to the target pump discharge amount to be obtained.

A mixer drum driving apparatus includes an auxiliary fluid pressure pump that is provided independently of a fluid pressure pump and is capable of supplying a working fluid to a fluid pressure motor so as to cause a mixer drum to perform agitation rotation, a plurality of motors configured to drive the auxiliary fluid pressure pump to rotate, and a control unit that controls rotation of the mixer drum. When an engine is stopped during the agitation rotation of the mixer drum, the control unit drives the auxiliary fluid pressure pump to rotate by operating the plurality of motors selectively in accordance with a load of the mixer drum.

A hydraulic system of a vehicle includes a first pump for supplying at least one first hydraulic circuit and at least one second pump for supplying at least one second hydraulic circuit with hydraulic medium. The second pump supplies the first hydraulic circuit with hydraulic medium in an emergency mode or when an output pressure of the first pump fails.

The present disclosure relates to a hydraulic circuit, comprising: a hydraulic displacement unit for driving an implement; a hydraulic machine fluidly connected or selectively fluidly connected with the hydraulic displacement unit the hydraulic machine having a fixed hydraulic displacement; an electric machine drivingly engaged or selectively drivingly engaged with the hydraulic machine; a hydraulic pump fluidly connected or selectively fluidly connected with the hydraulic displacement unit, the hydraulic pump having a variable hydraulic displacement; and an electric motor drivingly engaged or selectively drivingly engaged with the hydraulic pump.

A hydraulic system includes: a cylinder that moves a moving object in a vertical direction by extension and retraction of a rod; a first bidirectional pump connected to a head-side chamber of the cylinder by a first supply/discharge line; a second bidirectional pump connected to a rod-side chamber of the cylinder by a second supply/discharge line and coupled to the first bidirectional pump in a manner enabling torque to be transmitted between the first and second bidirectional pumps; a relay line connecting the first and second bidirectional pumps such that a hydraulic liquid discharged from one of the first and second bidirectional pumps is introduced into the other of the first and second bidirectional pumps; and a servomotor that drives the first or second bidirectional pump. At least one of the first and second bidirectional pumps is a variable displacement pump whose delivery capacity per rotation is freely variable.

A hydraulic system includes: a cylinder that moves a moving object in a vertical direction by extension and retraction of a rod; a first bidirectional pump connected to a head-side chamber of the cylinder by a first supply/discharge line; a second bidirectional pump connected to a rod-side chamber of the cylinder by a second supply/discharge line and coupled to the first bidirectional pump in a manner enabling torque to be transmitted between the first and second bidirectional pumps; a relay line connecting the first and second bidirectional pumps such that a hydraulic liquid discharged from one of the first and second bidirectional pumps is introduced into the other of the first and second bidirectional pumps; and a servomotor that drives the first or second bidirectional pump. At least one of the first and second bidirectional pumps is a variable displacement pump whose delivery capacity per rotation is freely variable.

A dynamic system for a lifting apparatus is disclosed. The dynamic system includes a first motor and a second motor decoupled from the first motor. During the ascent of the lifting apparatus, only the first motor is involved in the driving of the lifting apparatus. During the descent of the lifting apparatus, only the second motor is involved in charging the battery system. Since the first motor and the second motor are decoupled from each other, the first motor can have a high driving efficiency and the second motor can have a high power generation efficiency, the problem that when only one motor is adopted, the motor needs to balance between the driving efficiency and power generation efficiency is solved. The energy recovery rate of this invention can be increased from 10% in the prior art to about 30%.

The present disclosure relates to a hydraulic circuit comprising: a hydraulic displacement unit for driving an implement; a hydraulic machine fluidly connected or selectively fluidly connected with the hydraulic displacement unit the hydraulic machine having a fixed hydraulic displacement; an electric machine drivingly engaged or selectively drivingly engaged with the hydraulic machine; a hydraulic pump fluidly connected or selectively fluidly connected with the hydraulic displacement unit, the hydraulic pump having a variable hydraulic displacement; and an electric motor drivingly engaged or selectively drivingly engaged with the hydraulic pump.

A hydraulic system of a vehicle includes a first pump for supplying at least one first hydraulic circuit and at least one second pump for supplying at least one second hydraulic circuit with hydraulic medium. The second pump supplies the first hydraulic circuit with hydraulic medium in an emergency mode or when an output pressure of the first pump fails.

Provided is a hydraulic pump arrangement including a plurality of motor-pump units connected to a common confluence, wherein each motor-pump unit of the hydraulic pump arrangement includes a pump realized provide pressurized fluid at its outlet; a motor arranged to drive the pump; a bypass valve configured to relieve pressure at the pump outlet; and wherein the hydraulic pump arrangement further includes a controller configured to receive a feedback signal from each motor-pump unit and to actuate the bypass valve of a motor-pump unit on the basis of the motor speed of that motor-pump unit. Further provided is a method of operating such a hydraulic pump arrangement, and a wind turbine including a number of such hydraulic pump arrangements.