| 摘要 |
In a pivotally mounted rock drill boom and feed bar apparatus, the pivots of the boom and the feed bar positioner include angle sensors comprising cam actuated fluid pressure regulating valves. The pressure regulating valves are disposed in a control circuit which includes a pilot pressure fluid actuated control valve which senses an unbalanced pressure signal generated by the sensor connected to the boom pivot in response to movement of the boom about said pivot. The control valve responds to the unbalanced pressure condition by valving fluid to the feed bar positioner actuator to maintain the feed bar in a predetermined directional attitude. The angle sensor mounted on the boom pivot may be adjusted independent of movement of the boom to cause a change in the directional attitude of the feed bar as desired. |
