what is an electric interlocker?

[markpierce]

Page 298 of Southern Pacific's Western Division says. "Just west of East Pleasanton was Radum Tower...where the SP's San Ramon Branch crossed the Western Pacific to join the Niles-Tracy main line. The two-story tower, built in 191, housed a 16-lever electric interlocker."
So...what is an "electric" interlocker versus a manual(?) interlocker. And when did railroads begin (if ever) start using electric machines from local towers to control turnouts versus the mechanical kind with linkage to the local tower?

[ericsp]

My guess is that an electrical interlock is a circuit that ensures when the signal for one line is not red the signal for the other is red.

[Anonymous]

Probably refers to electric switches versus Armstrong levers...

[CSSHEGEWISCH]

Electric or pneumatic power to throw the switches instead of rod connections began in the 1920's. Such an arrangement allows more switches to be controlled at a greater distance from the tower than rod connections. Although several towers in the Chicago area with rod connections remained unrebuilt into the 1990s, most of the others used electric switch motors. And Brighton Park is still not an interlocking.

Food for thought, throwing a switch thorugh rod connections requires you to move the weight of the rods as well as those of the switch points.

[jchnhtfd]

A full electric interlocker will also perform the interlocking functions (you can't change switch X until switches Y and Z are set and signals Q and R are set kind of thing) electrically, usually through relays and contacts on the various controls. Earlier interlockers used the mechanical interlocking in the cabinet to perform this function, and controlled the signals and switch motors electrically.

And nowadays the whole dang thing is done with computer programs... and you hope there are no bugs in them...

[Anonymous]

Today interlockings are referred to as Manual or Automatic. The Electric interlocker may be referring to one of those. If I had to guess the Automatic. I have never encountered an interlocking that had turnouts within it.

[indbill1]

An electric Interlocker refers to a mechanical interlocking machine that controlled signals and switches by electric power versus mechanical or pneumatic control. These machines were built in the early 1900s. The major manufacturer was the General Railway Signal Co. of Rochester N.Y. although there were other manufacturers. The signals and switches were operated by electric motors. Many of these are still in service on the IND Division of the N.Y.C. Transit Authority and were originally installed on the BMT Division in the early 1900s although they have been replaced by CTC Interlockers.