Hi /sci/, I hear you're smart.
If the stop request cord on my bus isn't physically connected to the front, how does it send its signal?
the cord is connected from front all the way to the back and to the front again
there's glass fiber inside the cord, once you pull it you are making the cord and thus the glass fiber longer
as you may or may not know, light is send trough glass fiber
each X ms a light pulse is sent trough it, as you're pulling on the cord it will take the light slightly longer to get back to the front
this delay is detected by the system that sends the light pulses
There's a simple spring-loaded switch at one end of the cord. It's like a standard push-button, but I guess it's technically a pull-button. Pulling the cord moves the switch and closes a contact. A DC pulse is sent via wire (typically routed under a floor or side panel) to a buzzer or bell, and maybe to the control logic that lights up a light or whatever.