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Re: Slip Coaches: Back When British Express Trains Detached Passenger Cars at Speed
Author: Dr Zarkoff
Date: 07-09-2018 - 23:35
> And when Smith showed his vac brak in competition, Brits lamented that there was no British brake. ONe writer went so far as to say Smith claimed not to be American but was a brit expat
Hodge's and Martin-duTremblay's vacuum systems predate Smith by at least 10 years.
> Brits claimed the vac was soooo simple and the triple sooo complicated.
Well, the were correct. Straight vacuum required only hoses and a piston. To make the system automatic required the addition of a check valve in the piston. Somehow a simple check valve is a lot less complicated than a three function triple valve.
> With size came weight such that vac parts were heavier than WAB parts
What I was referring to was that on those heavy goods wagons, the diameter of the vacuum brake cylinder itself was so large that it protruded beyond the sides of the carbody so much that the wagons were restricted in which tracks they could be used on.
The other thing about vacuum brakes is that the maximum force which can be developed by a certain diameter cylinder is finite: 14 psi (approximately), while with a compressed air system there is no such limitation.
> Creamer, a US inventor of a 'wind-up" brake went to Britain to show his device [185x] and spoke before engineers.
Turner mentions the Creamer brake. The Heberlein brake, a mechancial continuous brake wound up by the forward motion of the train when a cable is pulled, is still certified for use on preserved equipment on the Lößnitzgrundbahn in Saxony (Lossnitz Valley Railway).
Hodge's and Martin-duTremblay's vacuum systems predate Smith by at least 10 years.
> Brits claimed the vac was soooo simple and the triple sooo complicated.
Well, the were correct. Straight vacuum required only hoses and a piston. To make the system automatic required the addition of a check valve in the piston. Somehow a simple check valve is a lot less complicated than a three function triple valve.
> With size came weight such that vac parts were heavier than WAB parts
What I was referring to was that on those heavy goods wagons, the diameter of the vacuum brake cylinder itself was so large that it protruded beyond the sides of the carbody so much that the wagons were restricted in which tracks they could be used on.
The other thing about vacuum brakes is that the maximum force which can be developed by a certain diameter cylinder is finite: 14 psi (approximately), while with a compressed air system there is no such limitation.
> Creamer, a US inventor of a 'wind-up" brake went to Britain to show his device [185x] and spoke before engineers.
Turner mentions the Creamer brake. The Heberlein brake, a mechancial continuous brake wound up by the forward motion of the train when a cable is pulled, is still certified for use on preserved equipment on the Lößnitzgrundbahn in Saxony (Lossnitz Valley Railway).
