Fluid cylinder position sensor mounting apparatus

Claim 1

A position sensor mounting apparatus for attachment to a fluid operated, expansible cylinder of the type having a piston movably disposed within a chamber, and a threaded bore formed in the cylinder in communication with the chamber, the sensor mountable within the bore for detecting the position of the piston, the mounting apparatus comprising: a housing having a first portion with an internal cavity and a second integral portion having a cross section smaller than the cross section of said first portion, a first annular shoulder formed between the first and second portions of the housing, a through bore formed in the second portion of the housing in communication with the cavity in the first portion, the through bore being adapted to receive and support the position sensor therein; a coupling member including a first portion with a first cross section and a second integral portion having a second smaller cross section, an annular shoulder formed on the member between the first and second portions; the coupling member having a bore formed therethrough for receiving the second portion of the housing and rotatably mounting the housing within the coupling member for free rotation within the coupling member without simultaneous longitudinal translation with respect to the coupling member; a plurality of external threads formed on the second portion of the coupling member adapted to threadingly engage the threaded bore formed on the cylinder to fixedly mount the coupling member on the cylinder; first seal means disposed between the coupling member and the cylinder for forming a fluid-tight seal therebetween; and second seal means disposed between the coupling member and the housing to form a fluid-tight seal therebetween; said second portion of said housing including an extension projecting past said plurality of external threads, a groove formed in said extension, a retaining ring snugly engaging said groove, said retaining ring abutting an end of said plurality of external threads; and wherein said retaining ring prevents the separation of said coupling member from said housing while allowing free rotation of said housing relative to said coupling member, and when the plurality of threads are threadingly engaged in the threaded bore formed in the cylinder said retaining ring is hidden and cannot be removed, and the threaded bore on the cylinder positively retains said retaining ring against unintended removal.