Abstract: A magnetic proximity sensing apparatus for sensing ferro-magnetic objects is especially well adapted for use with fluid cylinders having pistons formed from magnetically attracted material. The apparatus includes a magnetic actuator responsive to the proximity of the fluid cylinder piston or other ferro-magnetic object which closes a switch and enables electrical circuitry for controlling fluid valves or other apparatus. A reed switch mounted within a hollow, cylindrical, permanent magnet has a separate pole piece secured at one end of the reed switch. The proximity of a ferro-magnetic object changes the flux within the magnet, closing the reed switch. The circuitry is solid state and includes a silicon controlled rectifier acting as a gated switch for completing the circuit.

Abstract: The specification discloses a magnetic proximity sensing apparatus especially adapted for use with fluid cylinders having pistons formed from magnetically attractable material. The apparatus includes clamping means for securing it to a tie rod of a fluid cylinder or directly to the cylinder body in juxtaposition to a side of the cylinder without disassembly of the cylinder. Also included are magnetic actuator means responsive to the proximity of the fluid cylinder piston which close a switch and enable electrical circuitry for controlling fluid valves or other apparatus.

Abstract: Valve-positioning apparatus especially adapted for use with fluid-operated spool valves for positioning the spool member of such a valve in a predetermined position whenever the valve is not operating such as upon installation or during shutdown. In the preferred embodiment, the positioning apparatus includes a piston member normally held out of contact with the spool by fluid pressure but urged into contact with the spool to position the spool when fluid pressure fails or is absent. The positioning apparatus may be used on either or both ends of the spool valve.