More WP&Y, and reply to Bill Barbour

Bill...
Thanks for your observations on the WP&Y car design article. I'll comment briefly on some the points you make, and add a couple things. (I've posted this as a new item, as the earlier thread is falling off the bottom of the page.)
It was careless of me to call the ABDX valves "triple" valves. The official nomenclature is "control" valve. I improved my knowledge of all this, thanks to your remark, by going to the huge WABCO website (via Yahoo). After this, I took a look at "WABCOPAC II TRUCK MOUNTED BRAKE ASSEMBLY". I was surprised at the complexity of the assembly, and the number of parts involved. (I had thought the approach might be simple and elegant for a newly designed, but traditional looking, truck. Now, I doubt that.) You're preaching to the choir when you bless cast iron as a brake shoe material. I've been a fan of cast iron ever since I built a live steamer, and found how nicely (although dirtily) it machined.
A little story: When we were converting D&RGW boxcars to passenger service for the C&TS RR, in 1971, the FRA wanted us to convert to type AB brakes. (The cars have K-type triple valves.) We would have had to change out everything, including the brake cylinders, and face the unpleasant prospect of running equipment of both types in one train during the transition. We ignored the suggestion, and never regretted our decision.
Based on your comments about steel and wood, I suspect that you may not realize that the main goal of my (unauthorized) design project is to come up with a safe, good tracking car, built from aluminum. The weight saving potential is immense, as aluminum weighs one-third of steel. To give you an idea of the possible saving, the WP&Y cars weigh 33,000# without trucks. (I may have reported this incorrectly in my first post.) So, building the car body out of aluminum might bring its weight down to 11 to 16,000#, for a total car weight in the range of 20 to 25,000#. This would improve the economics of C&TS RR operations significantly.
I've had to "go back to school" as regards structural design in aluminum, as my earlier training was limited to steel. (But then, my training in electronics concentrated on vacuum tubes, with transistors being sort of a curiosity. That was satisfactorily overcome in the 1970's.) A few of the things that are different about designing with aluminum are that you want to join things with rivets, or bolt them together (with stainless steel fasteners), instead of weld them (which weakens the alloys near the welds); you need to choose the alloy you specify, considering the corrosion environment and the strength required; and the finishing options are quite diverse. Incidentally, some large buildings, some high speed ferry boats, some railroad cars, and all aircraft are built with aluminum. I'm searching for good examples, which would help to make my points. One last point: In a design of this nature, you are far more concerned with stiffness and the avoidance of buckling, than you are with pure brute strength. I probably have a lot of convincing to do with the powers-that-be, but will have plenty of very good evidence.
Bob Keller