Patent ID: 7584784

Claim:
A reciprocating drive apparatus for connection to a top end of a rod string to drive a downhole pump located in a well, the apparatus comprising: a plate adapted to be fastened to a top end of a well head assembly of the well; a mast pivotally connected to the plate such that the mast can be moved from a substantially horizontal idle position to a substantially vertical working position; a hydraulic cylinder operatively connected to a source of pressurized hydraulic fluid; wherein the hydraulic cylinder is attached to the mast such that when the mast is in the working position the hydraulic cylinder is oriented substantially vertically, and such that the hydraulic cylinder can extend and retract in response to a controller; a tether adapted to be fixed to the well head at a first end thereof and adapted for attachment to the top end of the rod string at a second end thereof; wherein the tether is configured such that the hydraulic cylinder engages the tether to move the second end of the tether up and down as the hydraulic cylinder extends and retracts.