Contact device for use in the testing of printed circuits and a removable contact head for use in such a device

Claim 1

A contact device for use in the testing of printed circuits comprising a guide tube, a coiled compression spring housed in the tube, a contact head mounted for axial sliding motion in the tube against the action of the spring, and a seating member carrying the tube, wherein: the guide tube is fixedly secured to the seating member, the spring has one end portion fixedly secured adjacent the seating member, the other end portion of the spring being formed with a plurality of mutually contacting turns and the turns of the spring having an outer diameter less than the inner diameter of the guide tube, said other end portion having a final turn; and the contact head is removably secured to said other end portion of the spring and comprises therefrom a smooth cylindrical, retaining end portion having a tapering engagement tip, the inside surface of the guide tube being formed with a sloping shoulder against which bears said final turn to tighten said final turn against said retaining end protion of the contact head when the latter is not urged inwardly of the tube, said retaining end portion having a diameter very slightly greater than the inner diameter of the turns at said other end portion of the spring whereby the contact head may readily be engaged in the tube or withdrawn therefrom by subjection of the contact head to a rotary movement in a direction opposite to that of the spring turns to engage or disengage said retaining end from said other end portions of the spring.