| 摘要 |
A bit and block assembly in which the bit includes an elongate shank that is rotatively mounted in a block bore extending through the block, the bit shank being provided with an end extending through and beyond the mounting bore and laterally clear of the block. A bit head includes means adapted to strike a wall to turn the bit upon picking of the wall by the head. A locking means is carried by a lateral block portion that is spaced from the shank end, the locking means engaging the shank end to preclude unintentional withdrawal of the shank from the bore, yet enable turning of the shank, the lateral block portion protecting the locking means while the lateral space peripherally about the shank end enables cuttings to move through the bore and out of the block and to fall free axially of the shank end.
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