The right end of the fork is pivotally connected to the crank (2) which sets the fork in motion when moving around its base actuated by pneumatic cylinder (3) rod.
Drawing 17. Pipes Uncoupling Mechanism.
1 - fork; 2 - crank; 3 - brake cylinder; 4 - base; 5 - swivel wrench; 6 - guide.
There are two slots in the guide (6) that permit to adjust fork height. When air is supplied to the cylinder the crank turns to the left and moves the fork to pipe lock. When air supply is stopped the pneumatic cylinder spring sets crank in the original position causing the fork move from the lock.
When tubes are recovered from the well the swivel wrench (5) must be put into the lock slot of the lower tube; the swivel wrench centralizes the drill string according to the well axis; the drill string goes through the orifice in the rotary table. At the end of swivel wrench there is a handle welded to the top; at the bottom there is arrester inserted in the rotary table slot.
When pipes are being uncoupled the rotary is actuated. Rotation of the rotary table is transmitted via the fork to the drill string. The fork moves to the upper pipe. As soon as the lock slot concurs with the fork slot the fork moves into the slot and stops the upper pipe. The upper pipe is locked but the rotary continues rotating together with drill string; it causes uncoupling of upper and lower pipes. Upon completion of uncoupling the fork (1) sets in original position and the pipe is taken away.
The mechanism is delivered at customer’s request at special price.