The Contactor No. 153C was first issued with the No. 153 Block Signal in 1940. Carried over into the Post War period, it was issued with many accessories that had used the No. 41 Contactor during the Pre-War period like the No. 45N Automatic Gateman and the No. 152 Crossing Gate. This contactor was available throughout the entire Post War Era with the exception of one year: 1967.
It is a single-pole double-throw (SPDT) switch that is placed beneath the track, and when adjusted properly to the weight of the train, will cause current to discontinue contact with one set of points and initiate contact with another. The No. 153C could work with any accessory that used the No. 145C Contactor, but the No. 145C would not work properly with any accessory that required the No. 153C like the No. 450 Signal Bridge.