Designer Times
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I became fascinated with just how the different materials and specific detail features of parts determine the smooth function and life of machines. Especially welded steel parts, which we call weldments. These are very common in machine design. Disneyland was filled with steel weldments, some good, some needing help.
Quick engineering lesson in material fatigue: Flex a paper clip back and forth severely and you get two busted parts pretty quick. Flex it just slightly, now it’ll take a long time to get the two parts. The first was high stress bending with a just few cycles to destruction, the second, low stress bending with many cycles to failure.
With plain mild steel, reverse bending stresses above a force of say 30,000 psi (pounds per square inch) will fatigue crack after only a few thousand cycles. But lower the stress to 5,000 psi and the part has an unlimited life. But it’s awful big for the job. So, try to get the size of the part reasonable for the load and number of cycles. That’s the trick.
Do it by careful calculations and design, or do it by “trained eye”. Both will get you a good part. You can study the engineering of parts in college, and you can study busted parts. Same knowledge, if you develop a good “eye”. Over time you get a good feel for good design and bad design. It’s a lot better when you learn from the broken stuff designed by others rather than by yourself.
Disneyland in 1955 was a gold mine of engineering evidence. From this, we all learned the lessons of good long-life attraction machine design. Many of our young designers became experts at excellent new custom Disney designs, even without formal college training. They were already enrolled in the “Disneyland College of Experiential Engineering”.
During these redesign sessions I got a chance to work with Karl Bacon and Ed Morgan of Arrow Development. They built a lot of the Disney ride machines over the years. They were never upset that Roger Broggie had me redesigning their products. We were both interested in getting it right for Walt. And I learned so much from their designers and fabricators as to their very clever ways to design and build neat stuff.
One redesign experience was when Disneyland became weary of welding up the Tea Cup ride. Roger Broggie gave me the redesign task. I spent hours laying on my back underneath the ride when it was running, just watching all the parts in motion until I had an idea of what the cure should be. I drew up the plans for a new Tea Cup structure and wheel support system, it was built and reinstalled in early 1956. No more welding. But It’s still the only Disneyland Ride I’ve never been on, but been under a lot.
Next month: Main Street Vehicles - Antique Cars - Omnibus - Fire Engine
-- Bob Gurr
Bob Gurr began working with Disney in 1954. He retired in 1981 but occassionally consults for the Company. Since Disney he's worked on the sinking ship at Las Vegas' Treasure Island, Universal Studios' King Kong, Godzilla for the film by the same name and much more. Among his proudest accomplishments he lists "making Walt tickled pink that some of the things he wanted to build actually worked. You could tell how proud he was when he would show off things to his friends and the press. Lincoln and the Monorail were two big ones for him."
Designer Times is normally posted the second Wednesday of each month.
The opinions expressed by Bob Gurr, and all of our columnists, do not necessarily represent the feelings of LaughingPlace.com or any of its employees or advertisers. All speculation and rumors about the future of Disneyland and the Walt Disney Company are just that - speculation and rumors - and should be treated as such.
-- Posted January 10, 2001
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