| 摘要 |
Lockable overshot ( 10 ) includes an elongated body ( 12 ), lifting dogs ( 14 a , 14 b) and a locking sleeve ( 16 ). Ends ( 18 ) of the lifting dogs ( 14 ) are configured for latching a conventional spearhead point therebetween. The locking sleeve ( 16 ) is retained on the body ( 12 ) and is provided at one axial end with a circumferential wall ( 66 ) and two diametrically opposed gaps ( 68 ). The locking sleeve ( 16 ) is rotatable on the body ( 12 ) between a locked state preventing ends ( 18 ) of the lifting dogs from pivoting away from each other to release a previously latched spearhead point, and an unlocked state where the locking sleeve ( 16 ) allows the lifting dogs ( 14 ) to move so that the ends ( 18 ) can be pivoted away from each other to release a previously latched spearhead point. In this regard, the locking sleeve ( 16 ) is provided at one axial end with a circumferential wall ( 66 ) provided with a pair of diametrically opposed gaps ( 68 ). When the locking sleeve ( 16 ) is in the locked state, the wall ( 66 ) is disposed inside or between ends ( 56 ) of the lifting dogs ( 14 ). This prevents the ends ( 18 ) of the lifting dogs from pivoting away from each other. When in the unlocked state, the gaps ( 68 ) register with the ends ( 56 ) of the lifting dogs ( 14 ) so that the ends ( 56 ) can be pivoted toward each other thereby pivoting the ends ( 18 ) away from each other to release a previously latched spearhead point. |
