Hi all,

I am looking for some information. A client of mine has me machining cylinders for his Erie K-5 Pacific model in 1 1/2" scale. These locomotives had what looks like the VILOCO cylinder bypass and relief valves.

Does anybody know if there are any drawings available that I can copy? The 1947 Locomotive Cyclopedia has their ad on page 599.

Thanks!

Andy Pullen

This is very late, but since you appear to have received no information, it may be useful.

Reading T1 2100 has a complete (if apparently slightly modified) installation of a form of VILOCO relief device, from which you could make measured drawings or (presumably) perform a teardown to inspect the internal parts and dimensions.

I suspect these may have been made in one size, with the bypass pipe being the only component (possibly) needing to be changed to conform to the stroke.

Note that the original form is "Whelan" bypass valves (as famously applied to the Milwaukee F6 locomotives) and in that form were described explicitly as 'bypass and relief' valves (having separate poppet valves for each function) -- the original patent is here:

https://patents.google.com/patent/US1353296A/en

and there are cross-sections and a couple of drawings here for an early (1923) version:

https://books.google.com/books?id=VPzmAAAAMAAJ&pg=PA300&dq=whelan+bypass+valve&hl=en&sa=X&ved=2ahUKEwjn7ci0tvfkAhUNna0KHYQPBukQ6AEwAnoECAAQAg#v=onepage&q=whelan%20bypass%20valve&f=false

Interestingly, I can find no patent for the different arrangement applied to the Reading T1s -- it is not cited as a precedent in a later bypass arrangement (Kelly's) submitted a year later than the construction date of the locomotives and granted in 1950.

The bypass pipes on 2100, and perhaps on other T1s, have been modified (or perhaps were made) with a 'plurality' of small holes, which essentially spoil potential use of the device as a Wagner-type air-excluding bypass. This may have been done due to excess residual or compression pressure; I suspect this is a 'known' issue in the history of these locomotives but I have never seen it carefully documented.