摘要 |
A self-propelled, pneumopercussive, cyclic action, ground penetrating machine (200) has decreased energy consumption and increased average working velocity compared to conventional machines. This is obtained in part by a valve-operated air-distribution mechanism (203) having separate forward and reverse compressed air supply lines (35, 37), which mechanism (203) does not limit the length of the forward and backward strokes of the striker (202). This mechanism allows the backward stroke chamber (75) to be connected with the atmosphere during the entire forward stroke of the striker (202). This eliminates generation of an air buffer in the backward stroke chamber (75) and, consequently, the striker (202) does not lose part of its kinetic energy before impact. The invention also provides a cyclic action braking mechanism (204), a forward/reverse mode control system (205) which can be pneumatically actuated, a movable chisel (207) which utilizes the energy of the striker more efficiently and has a gasket (72) to prevent jamming, and a sensor (208) for monitoring the impact frequency of the machine (200) so that it can be quickly switched to reverse mode upon encountering an obstacle.
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