How do token signal boxes work?

Question

does anyone know how the token signal boxes work? and about the special TPWS braking system?

Answer 1

As a footnote, the same system used in the US was called the "staff system."  If you had possession of the staff (actaully a stick) you had the railway.

Practiced near the end of its time only on branch lines, it has been disused since the '70s.

Answer 2

TPWS involves an arming loop and a trigger loop. When the train passes over the arming loop, a timer is started. If the trigger loop is passed within the time limit, then the train is going too fast and the brakes are triggered. The target speed is thus defined by the distance between the arming and trigger loops.

Token working involves one or more token instruments which are interlinked to only allow one token to be out at any one time. If you're not in possession of a token, you don't have permission to proceed.