Cowboy pumpjack

Calgary, Canada - A pump jack, nodding donkey, pumping unit, or horsehead pump is the overground drive for a submersible pump in a borehole.

A pumpjack is usually driven by an electric motor and 'nods' at a regular rhythm. An electric motor (or, more rarely, a natural gas or diesel engine) turns a pair of cranks, which by their action raise and lower one end of the beam. The other end of the beam has a curved end, resulting in the shape likened to a donkey or horse's head. This converts the rotary mechanism of the motor to a vertical reciprocating motion to drive the pump shaft. The engineering term for this type of mechanism is a walking beam.

This system is also commonly referred to as a beam pump, rod pump, grasshopper, thirsty bird or jack pump. This type of arrangement is commonly used in onshore applications for relatively low-production oil wells.

From my collection of stock photos of Canada