Re: The Strange Story of Sumpter Valley Caboose #4 / U.S.A. Caboose #909

Dave would likely know.

The early triple valves had a three position cutout built into them. That allowed them to be cut out entirely, in automatic brake position, or connecting the train pipe directly through to the brake cylinder. The original intent was to allow the transition from the straight air system to the automatic brake system.

Dave said that the straight air system was not widely applied on most railroads. They gravitated towards equipping their passenger trains first since they were typically assigned dedicated engines and cars, ran at the highest speeds and the greatest liability.

One of the Colorado narrow gage engineer biographies stated they stopped at the top of a mountain pass and set the triple valves to direct/straight air for the trip down the steep grade. Later triples and Ks did not have this feature so they had to use retainers and cycle braking.

Didn't the real early D&RG (2-4-0 and 4 wheel cars) start out with Aames vacuum brakes? So did they try straight air only before the early triples?