| 摘要 |
<p>A portable, horizontal earth boring machine which employs two or more hydraulic motors to rotate and advance an auger in an earth boring operation in which the motors are supplied with hydraulic fluid from a single variable displacement pump located remotely from the earth boring machine. The pump is controlled to respond to the loads imposed on the motors to limit the horsepower output of the pump up to a predetermined maximum after which the horsepower is maintained constant until a maximum working load is achieved at the motors. The control is so arranged that demands made by an operator of the earth boring machine in excess of the limits of the pump are negated making possible the selection of an engine to drive the pump of sufficient capacity to meet but not greatly exceed the power requirements of the pump.</p> |
