Pumping heavy sweet crude from the heath formation just north of dickinson nd.
Air balanced pump jack.
In the early days pumpjacks worked by rod lines running horizontally above the ground to a wheel on a rotating eccentric in a mechanism known as a central power.
The central power which might operate a dozen or more pumpjacks would be powered by a steam or internal combustion engine or by an electric motor.
Manufactured to api standards these units deliver high reliability and quiet operations.