Wiktionary
alt. (context US English) The ground-based drive for a submerged pump in an oil borehole n. (context US English) The ground-based drive for a submerged pump in an oil borehole
Wikipedia
A pumpjack (also called oil horse, oil jack, donkey pumper, nodding donkey, pumping unit, horsehead pump, rocking horse, beam pump, dinosaur, grasshopper pump, Big Texan, thirsty bird, cricket, or jack pump) is the overground drive for a reciprocating piston pump in an oil well.
It is used to mechanically lift liquid out of the well if not enough bottom hole pressure exists for the liquid to flow all the way to the surface. The arrangement is commonly used for onshore wells producing little oil. Pumpjacks are common in oil-rich areas.
Depending on the size of the pump, it generally produces 5 to 40 litres of liquid at each stroke. Often this is an emulsion of crude oil and water. Pump size is also determined by the depth and weight of the oil to remove, with deeper extraction requiring more power to move the increased weight of the discharge column (discharge head).
A pumpjack converts the rotary motion of the motor to a vertical reciprocating motion to drive the pump shaft, and is exhibited in the characteristic nodding motion. The engineering term for this type of mechanism is a walking beam. It was often employed in stationary and marine steam engine designs in the 18th and 19th centuries.
Usage examples of "pumpjack".
IN FOUR DAYS' riding he crossed the Pecos at Iraan Texas and rode up out of the river breaks where the pumpjacks in the Yates Field ranged against the skyline rose and dipped like mechanical birds.