| 摘要 |
<p>The tunnelling machine mounted on crawler tracks has an adjustable boom at the front carrying a rotary cutter. The boom can be raised and lowered to make vertical cuts, and swung sideways. These operations are carried out by hydraulic actuator cylinders, and the cutter is driven by an electric motor. The volume of hydraulic fluid required is controlled by the load requirement of the motor, this requirement being a reciprocal figure. The hydraulic circuit includes a control unit operated by the electric motor supply, with a voltage converter arrangement which operates a servo valve to control a hydraulic cylinder at the input to the pump supplying the actuators.</p> |
