Patent GB-557131-A (GB)
Title: Improvements in or relating to interlocking systems of railway signalling
IPC: B61L19/06
Filed: 1942-01-30
Abstract: 557,131. Railway route-control systems ; electric switches. STANDARD TELEPHONES & CABLES, Ltd., and BROWN, A. Jan. 30, 1942, No. 1266. [Class 105] In railway route-control systems of the kind described in Specifications 496,495, 502,085, 512,895, 516,800, 520,058 and 556,581 in which route setting and interlocking are effected by the use of rotary sequence switches of the kind described in Specification 526,829, [Group XXXIX], arrangements are made to prove positively that a switch is at rest in a route position, to prevent a switch from driving except in response to a proved operating circuit, and to lock the switch rotor mechanically against hand operation in either direction from a route-setting position by a locking member released by the clutch magnet or a separatemagnet operating in conjunction with the clutch. The locking member may be associated with, and operate, a set of contacts which must change over before the locking member releases the rotor. These contacts may be arranged in a circuit which proves that the switch is at rest. The switch described in Specification 526,829 has a pawl and ratchet wheel allowing hand operation of the rotor in one direction, and the present invention replaces the pawl and ratchet wheel by a detent having a rectangular nose which engages in a peripheral slot in a disc to lock the rotor against hand operation in either direction, the detent forming the locking member referred to above. Figs. 1, 2, 3 are circuit diagrams extracted from diagrams of Specification 556,581. Assuming setting of route 14B to be required, panel switch 14B is reversed closing contacts R, Fig. 2. Switchdriving relay IZR is then energized from positive Bf6 over interlocking cam contact 4BC of sequence switch No. 4 (these contacts being closed in all positions except those allocated to conflicting routes Nos. 12 and 14A), contacts 14BR, contact of switch cam 1DH of switch No. 1 (closed continuously from home position up to the position corresponding to the desired route 14B), contacts 1DI of the same switch (closed only in the home position), and winding 1ZR to negative N1. Front contacts 1ZR3 close to maintain the above circuit after it has been broken at cam 1DI by the switch moving from home position, the circuit then being finally broken when cam 1DH reaches the position corresponding to the required route 14B. Before switch No. 1 drives, however, circuit of lock magnet 1Z, Fig. 1, and clutch magnet 1M is closed by front contacts 1ZR2. The armature of magnet 1Z forms the detent, above referred to, of switch No. 1 and also operates four sets of contacts. Magnets 1Z, 1M in series are connected between the positive lead Bf5 and negative lead N5 and back contacts 1Z1, 1Z2 of magnet 1Z are included respectively to the right in the positive lead and to the left in the negative lead. The lock and clutch magnets (not shown) of other switches of the system with their similarly disposed contacts are arranged in parallel with magnets 1Z, 1M, the arrangement ensuring that, by the opening of contacts 1Z1, 1Z2 (or the corresponding contacts of other lock magnets) the energization of the lock magnet breaks connection with the positive lead for all lock and clutch magnets to the right, and connection with the negative lead for all lock and clutch magnets to the left, so that only one switch can operate at a time. The correctness of the setting is proved by contacts of cam 1BR, Fig. 2, closed only when switch No. 1 is in the correct position for route 14B, energizing relay 1ZCR from positive Bf6 over cam 4BC (proving interlocking correct), contacts 14BR (proving panel key in reverse position) and lock magnet contacts 1Z4 (proving that relay 1Z is released and switch No. 1 is stationary in route position), to negative N1. Setting of signals and points for route 14B follows by means not shown. To restore the route to normal panel key 14B is operated to open contacts 14BR and close contacts 14B (N) Fig. 3. Circuit for restoring relay 1ZNR is thus closed from positive Bf1 over lock magnet contacts 1Z3, contact of cam 1BX closed only whilst switch No. 1 is in 14B route position, contacts 14B (N), relay 1ZNR to negative N1, a stick circuit for the relay being closed by contacts 1ZNR3 over cam 1BS closed except when switch No. 1 is in home position. Contacts 1Z3 prevent energization of relay 1ZNR by sudden operation of the panel key during forward drive of the switch.