Abstract: A pump jack system for an oil well comprising a walking beam having one end connected to a vertical pump rod while being pivoted intermediate its ends for rocking movement by means of a single vertical connecting arm driven through an eccentric connection to a cushioned wheel, preferably a pneumatic tire. The latter is driven by a motor through pulley and sprocket members which provide speed reduction to a horizontal drive shaft that engages across the surface of the wheel to drive the same. The other end of the walking beam is provided with weights slidable along the beam into adjusted positions for counterbalancing the forces imposed on the beam through the pump rod. The wheel is also suitably weighted to counterbalance the weight of the connecting arm and its bearing on the wheel. To automatically deenergize the motor when the pump rod is jammed in the well, a limit switch assembly is mounted on the beam adjacent the end at which the pump rod is located.