Designed primarily for use in the production of heavy and medium oil in conjunction with a screw-type pump in relatively shallow or medium wells, the device comprises an inner mandrel within an outer casing situated below the pump and connected to the pump casing and prevents right-hand rotation in the event that the torque reaction of the pump increases due to sand, for example, and attempts to rotate the pump stator together with the production string tubing, but at the same time allows vertical movement of the string to take place for withdrawal purposes. Once the production string together with the pump and the no- turn tool is lowered to the desired position, drag blocks engage the well bore casing thus holding or steadying the outer casing while the inner mandrel is rotated slightly so that cams thereon force slips into contact with the well casing thus preventing right-hand rotation of the outer casing which, because it is connected to the stator casing of the pump and to the production tubing, also prevents right-hand rotation of these parts thereby preventing separation at the loosest joint. Shear pins are provided in the event that the slips catch in a casing joint, casing perforations or the like when withdrawing the tool and a shear ring on the mandrel shears these pins when vertical movement of the assembly is initiated thus clearing the cams from the slip blocks so that slip springs retract the slips and allow withdrawal to continue.
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