Patent GB-722196-A (GB)
Title: Improvements relating to apparatus for operating railway traffic governing devices by double wire transmission
IPC: B61L7/02
Filed: 1952-02-15
Abstract: 722,196. Railway signalling apparatus; interlocking. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd., and MULHOLLAND, E. B. Jan. 29, 1953 [Feb. 15, 1952], No. 4064/52. Class 105. Double-wire transmission apparatus for the operation of railway signals or points wherein the cabin levers are clutched to their operating wheels by a member (catch handle bar) which also actuates the interlocking mechanism, is arranged so that independent movement of the operating wheel as by breakage of the wire transmission or the forcing of the points releases the member (e.g. by release of a detent from the catch handle bar), which thereupon moves (e.g. being spring-loaded) to actuate the interlocking mechanism to prevent any further operation; and a warning signal may be exposed. As shown, the lever 3 is journalled on the axle 2 of the wheel 4 and the clutch device formed by a stud 17 on a catch rod 9 slidably mounted on the lever, which stud slides into a slot 19 in the wheel when the rod 9 is moved radially outwards is controlled by a spring-loaded pawl 6 pivotally mounted at 7 on the lever 3 and engaging a notch 5 in a projection 4b of the wheel 4 by means of a roller 6d at the end of an arm 6a when the lever is in its normal unoperated position. The catch rod 9 is urged by spring 22 towards the axle 2 but is limited in movement by a second arm 6c, Fig. 3, of the pawl engaging with a lug 20 on the catch rod 9 when the lever and wheel are in their normal positions. The catch rod 9 is coupled at one end to the interlock mechanism 14 and at the other end to a catch handle 15 which on operation moves rod 9 away from the axle 2 to operate the interlock mechanism, and to bring the stud 17 on. the rod into the slot 19 to couple the wheel and lever. Rotation of the wheel independently of the lever from the normal position causes the pawl arm 6a to move out of the notch on to the projection 4b and the second arm 6c to disengage from the lug 20 on rod 9 which is thus freed to move towards the axle 2 to operate the interlocking mechanism 14. In this case the stud 17 on the rod 9 engages in a cam slot 18a or 18b in the wheel to move the member towards the axle 2. The wheel pro- . jection 4b may form both sides of the notch 5 as shown in Fig. 1 whereby rotation of the wheel independently of the lever in either direction from normal causes arm 6c to disengage from lug 20 so that rod 9 can move towards the axle 2. Push-pull and pull-pull operations by two levers operating on the same transmission wire are described. The catch rod 9 carries an indicator bar 23, Fig. 3, provided at each end with an indicator strip 23a, 23b, which is normally concealed by an associated plate 24a, 24b fixed to the lever, the strips being rendered visible only when the pawl arm 6c is disengaged from the lug 20 and the catch rod 9 moved towards the axle 2. In the case of double-lever apparatus the wheel of one lever must be free to rotate while the other lever is operated and preferably abnormal forces cause the pawl 6c of only one lever to disengage from its associated lug 20. To this end one lever is clutched to a modified wheel having a slide 25, Fig. 4, spring-, urged towards the spindle 2 to an inoperative position and is moved outwards by a stud 36 on the catch rod 9 moving into a slot 40 of a slideretaining strap to engage the end of the slide when the catch handle is gripped and couples the wheel and lever and forming a notch for the roller 6d between the bevelled edges 34 and 35 of the slide and wheel projection 23. On relative rotation of the wheel 4 to the lever 3 in anti-clockwise direction roller 6d is forced on to the surface of projection 28 causing pawl arm 6a to disengage from the lug 20 and the wheel 4 continues to rotate until a projection 42 thereon engages a stop-piece 41 of the lever 3 and the stud 36 moving along a cam path 39 in the wheel moves the rod 9 inwardly to display the indicator 23a, 23b and through the link 14 operate the interlocking mechanism. If the rotation of the wheel is clockwise, the roller 6d is held by a stop such as 6e, Fig. 3, above the surface of the slide 25 which is in its inwards position and rod 9 is held by arm 6c and lug 20, the stud 36 follow. ing the cam path 37 in the slide and produces no i nward movement of the rod 9. When the lever 3 and wheel 4 are in reverse position, should an abnormal force be applied to the transmission wire, roller 6d will be forced out of the notch formed by faces 34, 35 and the wheel will be free to rotate relative to the lever with the stud 36 travelling in cam groove 38 or 39 according to direction of rotation.