| 摘要 |
A crawler tractor with a dozer blade and fitted with accessories to loosen the ground in the strafing pit area of an Air Force gunnery range and simultaneously remove from the ground rocks the size of a man's fist and larger and spent projectiles. The tractor is provided with an electromagnet positioned ahead of the dozer blade. Positioned to the rear of the tractor, and pivotally attached to its frame by drawbars, is a chisel bar with a plurality of chisel blades. Just ahead of the chisel bar is a rock rake having a spine from which extend a plurality of forwardly projecting tines. The rake is supported with its tines at such an angle that their tips barely scrape the surface of the earth. Ahead of the rock rake, there is a drag consisting of a section of railroad rail suspended from the drawbars of the chisel assembly at a height sufficient to just scrape the surface of the ground during operation of the tractor. Operation of the tractor and its accessories in the strafing pit of an Air Force gunnery range thus accomplishes three operations, namely, loosening of the earth to soften it so that it can better absorb the impact of projectiles from flying aircraft using the gunnery range, the removal of rocks from the area to minimize the possibility of ricochets of projectiles fired by the aircraft and the removal of spent projectiles from previous target runs to further minimize the possibility of projectile ricochets.
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