SWITCHING ASSEMBLY FOR A HYDRAULIC PUMP JACK

摘要

A switching assembly for a hydraulic pump jack includes a non-magnetic cylinder having an exterior surface, and an interior surface that defines an interior bore. 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. An array of magnetically triggered sensors are mounted to the exterior surface of the cylinder at axially spaced regular intervals. A controller is provided that receives signals from the magnetically triggered sensors as the magnet element carried by the piston comes in proximity with and influences the magnetically triggered sensors. The controller controls piston positioning by selectively controlling the working fluid supplied by the fluid source to the cylinder.