GB129891A - Improved Apparatus for Ascertaining or Utilizing Variations of Flexure in a Beam. - Google Patents

Abstract

129,891. Sykes Interlocking Signal Co., W. R., and Tarrant, R. W. Oct. 28, 1918. Retractive switches.-Relates to apparatus of the kind in which a connexion between two cantilever arms fixed to a beam adjacent to its points of support actuates mechanism for utilising the variations or flexure of the beam, and consists in forming the connexion of a pair of toggle-links placed in the plane of the cantilevers and bearing against the free ends of the latter, the middle joints of the toggles being connected by a tensioned spring, and means being provided for utilizing the variations in the depth of the togglelinkage due to the flexure of the beam to operate an electric circuit controlling treadle on the permanent way of a line of railway. Clamped to the rail 13 are two cantilever arms 11 connected by a bar 15 so as to ensure proper spacing of the arms without interfering with slight relative angular movement due to flexure of the beam. Each arm is in the form of an open oblong frame extending in a vertical transverse plane relative to the rails. Fixed to the lower end of each arm 11 is a flanged socket 16 to receive a screwed stud 18 which may be moved in and out of its socket without rotation by a nut 22 and locked by a nut 25. The head of each stud is notched and formed with a vertical rib which engages the slotted ends of two leaf springs 20, 21, which in this construction form the toggle links. Parallel and vertical carrier bars 30, 31 are connected to the springs 20, 21 respectively at their middle joints. Between the carrier bars is a floating block 34, through holes in which arranged at each side of the vertical axis paes studs 32, 33, attached respectively to the carrier bars 30, 31. Fixed to the block is an insulated switch blade 35 having two arms 35<a>, 25<b>, which are adapted to engage pairs 36a, 36b of electric contact springs and establish electrical circuits when the block is rocked by the mid points of the springs approaching or receding from each other on flexure of the rail due to a train passing to or from the section of the rail between the cantilever arms. The inner carrier bar is slotted to give freedom to the nut 38 securing the pin 37. Adjustment of the switch blades 35<a>, 35<b> is effected by mounting the pins 31, 32, in slots in the carrier bars to which they are secured by nuts, while adjustment of the switch contacts 36<a>, 36<b>, is effected by mounting them on a bracket supported by the outside member 30 and adjustably secured to it by a slot and bolt. Adjustment of the initial longitudinal compression of the spring is effected by movement of the studs 18.