And lo, that was what was delivered unto me this week! 'Course, me being who I am, I wondered: Could I get these blinking things back into working order?
The 1930-33 vintage Lionel 91 circuit breaker as delivered. Despite the seller’s careful packaging, a corner of the 80+ year old casting broke off in transit; however, a touch of Loctite ACC gel put it to rights.
Interior of the 91. Note that it only has two lugs, making it the earlier version (more on this later). When I got it, the works were rusted shut and the coil, while live, was also gummed up. A bit of cleaning, oiling, spring tightening and rewiring later, it worked fine! This is the mechanism in the “on” position.
Mitch’s post is a good example of the advantage that thermal circuit breakers have over magnetic types for running toy trains. The purpose of the circuit breaker is of course to limit the current to a safe value. The problem, which he experienced, with the Lionel breaker illustrates that that circuit breaker does a poorer job of modeling the behavior of the wiring that it is meant to protect, compared to the Marx thermal breaker. The reason for limiting current is really to limit heat in the wiring. The thermal breaker does a reasonable job of keeping track of the wiring temperature, while the magnetic breaker trips immediately when the current exceeds its setting, even though the wiring may still be cool and no harm has been done yet. This behavior is called “nuisance tripping”, and it is not usually considered to be a good thing.
