Hello folks,
A quick review and update of our vacuum brake project.
Our design is, to the best of our ability, based on US Patent 241,333. Specifically, lines 24-65, in the text of the patent, is the complete basis for car equipment. As indicated beginning on line 32, a tenant of Eames’ design is avoidance of a packing gland on the double hemispheric shell type cylinders. For our prototype, rather than custom produce the smaller rod seal diaphragms, we utilized a standard rubber bellows, which is housed in a tube and arranged so that vacuum is on the outside of the bellows, atmosphere on the inside. We are utilizing the reservoir option as indicated beginning on line 63.
For control apparatus on the loco, reference line 40, beginning at “automatically operating ejector,” utilizing a diaphragm balancing train pipe vacuum with a set of weights. We took a liberty here and substituted the weights for a spring. The user input (engineers control) is to set the compression on the spring via a set of ramped discs. The mechanism either opens the train pipe to atmosphere or opens a pilot which snaps open a steam valve leading to the ejector. We prototyped this, in rather ugly fashion, last year to prove viability. We have now designed and are mid production on a version which is entirely self contained, 7” diameter and about 11” tall, which the ejector threads into directly.
The locomotive control equipment will be completely independent of the locomotive brake system, thereby keeping (for example) loco 9’s historic braking system completely un-modified. The train braking system on a locomotive will consist of a train pipe and a controller. Additional plumbing includes a steam line off the boiler, ejector exhaust (with muffler), condensate traps, and shut off valves.
We have chosen this system because it allows fully automatic continuous braking within the historic context of the braking system on this railroad. The car equipment is virtually identical to the straight brake found on the WW&F cars historically, requiring only the additional reservoir and some extra plumbing connections. The locomotive equipment is simple and easily removable.
We did prototype a much more complicated control system, involving a series of modern valves mounted under loco 9’s deck. That system proved unwieldy to troubleshoot, and was a far greater compromise on historic integrity. That equipment has all been removed; we’re all much more pleased with the current controller design.
Couplings: loco 9 came from CT with its vacuum hoses which included the European style couplings, which came from the WW&F in 1937. The hoses themselves were radiator hoses; we replaced them in kind (right from Wiscasset Napa).
With regard to John Scott’s question of angle cocks: we are using them so that we may isolate parts of the system for testing purposes. Said testing includes the seals on the couplings, which we’ve yet to come to trust. We also have yet to reproduce the stoppers as described. As we’ve been heavily in testing mode, and have only one car equipped, it hasn’t been high on our priority list to refine that aspect of the design. (IE we need a functional controller before the valves matter at all). As to the danger induced by the presence of these valves- we have accepted such risk as equivalent to that found on a positive pressure system, and we may just need to leave it at a difference of opinion.
The project’s delay due to controller production coincided nicely with the bridge project taking all of our attention. I do apologize if Mr. Scott, or anyone, has felt underinformed on this project. The reality is our resources have been otherwise required, and we really wanted to have the new controller prototype in hardware stage before making a major announcement. As it is, the controller production work has been proceeding back burner throughout this entire time.
We are also still refurbishing three B&SR vacuum cylinders; these will be for coach 3, which carried identical cylinders out of J&S (as evidenced by surviving mounting brackets). This work is waiting for the shop to get some heat. We have Jonathan St Mary who is essentially devoted to this project (pending heat), and several others who are supporting the project in various ways. I’m providing project guidance, however for the most part I haven’t been on hardware work. As winter brake work continues I’ll focus on 10.
Thanks very much for everyone’s interest.
Jason
