| 摘要 |
<p>A backspin reducing device for reducing an amount or a rate of backspin of a rod string when lifting the rotor apart from the stator of an oil or gas downhole progressive cavity pump. The backspin reducing device includes a substantially cylindrical housing having one or more threaded pin receptacles holding respective threaded pins in threaded engagement around a polished rod portion of the rod string of the progressive cavity pump. Turning threaded pins in their respective threaded pin receptacles causes the interior ends of the threaded pins to move towards or away from the polished rod in the center of the housing. Attached to the interior end of each threaded pin is a friction roller. Movement of the threaded pins towards the center of the housing forces the friction rollers to contact the polished rod and apply frictional torque resistance on the polished rod, thereby reducing the backspin of the rod string when the rotor is pulled apart from the stator, without impeding the upward or downward movement of rod string.</p> |
