SWITCHING ASSEMBLY FOR A HYDRAULIC PUMP JACK

摘要

A switching assembly for a hydraulic pump jack has a non-magnetic cylinder. A piston is reciprocally movable within the interior bore of the cylinder. The piston has circumferential sealing means to engage the interior surface of the cylinder. A magnetic element is carried by the piston. A fluid source supplies a working fluid to the cylinder, wherein the piston is moved by injecting working fluid into the cylinder. At least one magnetic sensor is externally mounted adjacent to the non-magnetic cylinder that senses at least a top of a piston stroke and the bottom of the piston stroke. A controller receives signals from the magnetically actuated sensor as the magnet element carried by the piston comes in proximity with and influences the at least one magnetic sensor. The controller controls piston positioning by selectively controlling the working fluid supplied by the fluid source to the cylinder.