| 摘要 |
The present invention relates to construction machinery such as wheel loaders, which comprises a steering actuator, a hydraulic pump able to discharge operating oil in two directions under drive by means of a swash plate, a pair of drive oil ducts constituting a closed loop connecting the steering actuator and the hydraulic pump, and a pump control unit which receives input in the form of signals in response to manipulation of a steering means by a driver; wherein the pump control unit comprises a swash-plate driving cylinder which is connected at one end to the swash plate (21) and is driven and varies the angle of inclination of the swash plate when operating oil is supplied and thereby varies the volume of discharge and the direction of discharge of the hydraulic pump, and a swash-plate control valve which receives input in the form of signals in response to manipulation of the steering means by the driver and is thereby turned around and so controls the amount and the direction of the operating oil supplied to the swash-plate driving cylinder. |
