| 摘要 |
844,607. Percussive tools. MARSHALL, G. W. Oct. 31, 1956 [Oct. 31, 1955; May 31, 1956], Nos. 31015/55 and 16809/56. Class 124. A drilling machine comprises a boom, a carriage movable along the boom, and connected to a drill unit, a drive motor feeding the carriage along the boom, a fluid-pressure actuated mechanism controlling the thrust exerted on the work by the drill, and means co-operating with the fluid-pressure actuated mechanism to operate the drive mechanism. As shown, a boom 1 carries a screw and nut device 2, 5; the nut being attached to a cylinder 6 having a piston 7 to which is connected a drill unit 9: The cylinder 6 has a valve cylinder 13 containing a valve 14 urged on to its seat by a spring 15 and having a rod 18 extending outside the casing. A finger 19 attached to the piston 16 co-operates with the rod 18 to open the valve 14 and allow pressure fluid to pass to a motor 3, driving the screw 2 to advance the nut and so move the drill unit in the direction of drilling. The drive mechanism may be a rack and pinion or a chain and sprocket and the drill unit may be attached to the cylinder in which case the piston is connected to the drive mechanism. If additional drilling pressure is required, pressure fluid may be supplied to the piston 7 to move it in the direction of drilling. Specification 844,608 is referred to. |
