Patent GB-190717347-A (GB)
Title: Improvements in and relating to Railway Signalling Apparatus.
Filed: 1907-07-29
Granted: 1908-05-21
Abstract: 17,347. Kershaw, A. G., and Saxby & Farmer. July 29. Controlling signals. - An electro-magnetic slot apparatus interposed in the wire connexions for mechanically operating signals comprises a pair of parallel levers 1, 1<a>, Fig. 2, to one end 2<a> of which is attached the semaphore connexion 3 and the other end of which is mounted on a pivot 2 on the casing. A bent lever 4 is also mounted on the pivot 2 to move between the levers 1, 1<a>, and carries a yoke 6 on a pivot 5 at the other end. The connexion 8 from the signal lever is attached to the yoke 6, and a connexion 9 leads from this end of the yoke 6 to a balance weight. A pair of links 11 connected by a pivot 10 to the levers 1, 1<a> is connected by a pivot 16 to a pair of links 13 attached by a pivot 12 to the lever 4. An electro-magnet 20 and its pivoted armature 16 are carried by a plate 15 attached to the levers 1, 1<a>, and roller 18 on a projection of the links 11 rests on a sloping surface 17 of the armature. When the connexion 8 is pulled to lower the signal to 'safety,' the yoke 6 is turned on its pivot until the web 6<a> of the yoke 6 engages with the lever 4, which then moves over, and through the links 13 and the links 11 moves the levers 1, 1<a>. The signal is then lowered if the magnet 20 is energized so that its armature is attracted, and retains the roller 18 on the sloping surface 17 to prevent relative movement of the links 11 and the links 13. If the magnet 20 is then de-energized, the roller 18 is no longer supported by the armature 19 and the links 11, 13 move relatively to one another, so that the semaphore is free to return to 'danger,' moving the mechanism into the position shown in Fig. 5. If the signal lever is then returned to normal position, the balance weight attached to the connexion 9 returns the lever 4 and the links to the normal position, a projection 6<b> on the yoke 6 being provided to raise the links 13, 11 ; a stop 25 determines the extent of upward movement of the links 11. If the magnet 20 is not energized when the signal lever is operated to set the safety' signal, a projection 6<a> on the yoke 6 moves the links 13, 11 relatively to one another and the levers 1, 1<a> are not operated to set the signal. A projection 21 on the links 13 is also moved into the path of a pivoted stop 22 to prevent the signal lever from being pulled right over under these circumstances. The circuit of the magnet 20 is of course controlled from another cabin or other controlling place, and the catch handle of the signal lever may also control a switch in the circuit. In a modified form, in which slides 26, 27, Figs. 8 and 9, replace the pivoted levers, the link 13 is attached by a pivot 29 to the link 11, which is attached by a pivot 28 to the slide 27. A pin 30 on the slide 26 moves in a slot in the link 13 and supports the link. A stop 31 on the slide 26 returns the links to normal position after their relative movement due to attempted operation of the signal when the magnet 20 is de-energized, and a projection 21 on the link 13 engages a pivoted stop 22 to prevent complete actuation of the signal lever under these circumstances.