Designer Times
Page 2 of 2
Anyway, back to the "purple X". We learned from the faults in the original Monorail, and thru the development period that a good Monorail needed several key features. Low weight with the lowest possible center of gravity, fully steerable load wheels, single rather than dual tires on top of the beam, and that the entire train must be tight-coupled car-to-car so that the complete train behaves as one mass. We also wanted a much newer and more reliable electrical propulsion system. The steerable load wheels would require some sort of steerable drive axle arrangement. The side suspension would have to both soft and hard in order to minimize the Disneyland segmented shape but ride softer with better side sway resistance.
Now, the regular Disneyland vehicle design technique that I had used from 1954 onwards was to buy stock car and truck parts, then combine them with a custom structure. In other words, never invent basic service parts even if your design has never been done before. Why not let the transportation industry do all your homework. Disneyland could go to the local car dealer to get service parts in later years.
I found that Rockwell Standard made a great steerable front axle for very heavy all-wheel drive trucks. This axle had bolt-on wheel ends with internal U-joints that had been in service since the mid 1930's. Goodyear now had those big fat Super Single tires available for use on transit mix trucks. We could get a special wheel made to fit the Super Singles to the Rockwell wheel end. Rockwell also made a big variety of differential axles which we could buy and chop down to a narrow set up. We could connect this rig to an electric motor with Mechanics brand U-joints and splined drive shafts. Aha! Nothing to invent! Just select and modify a bit here and there and we'd get a drive train that had all stock interior service items that already have been in truck service use for years.
In January 1966 Walt took (13) of us Imagineers on an Epcot sales tour to several companies including Westinghouse and General Electric......who just happened to make electric railway propulsion equipment. Both companies made technical proposals to us, Westinghouse with advanced AC power, GE with plain old DC power from the 1930's PCC car era, but modernized for improved service. We liked the GE 600VDC system because I could scatter their equipment all along the lower sides of the Monorail frames to balance out the weight distribution and get the low center of gravity. Only one small device had to be altered to fit. So, now we got the latest in stock street trolley car power. I could hang the heavy 150 HP electrical motors low on the sides connecting then to the steerable axle end and differential gearing mounted above.
The next trick was to design the inter-car steering so that each car steered the car connected to it.....sort of in a handshake layout. This had an advantage in that the car structural end frames were the same.....no need to make tooling for a right and left design. The side suspension almost defies description today. It was a coo-coo scheme where only one side arm was needed to carry both the upper and lower side wheels. It needs half the number of pivot bearings and springs. It does look goofy when running; any wheel not momentarily needed to hold the car upright slowly stops since it is lifted away from the beam when not required by the other wheel on the same arm. Some guests look up, see this and wonder why.
A Monorail car is a structural rats nest because as you make a less then transit sized car, everything has to get smaller except the passengers. The Center of gravity get higher, there's less space for equipment, the doors and windows are proportionally larger and so on. Name another vehicle that must contain within it's volume the passengers, all the equipment, all the wheels, and all the entire roadway! So the structural concept is most important. I choose honeycomb aluminum panels riveted together to form the floor, roof, and end bulkheads.
These honeycomb panels were much like aircraft practice at the time. We could design any detail closures we wanted since custom aluminum extrusions were inexpensive. The floor was a big thick slab, bulkheads a bit thinner, and the lower curved skirt panels quite thin. I designed the extrusions to allow fitting the panels together in a self-jigging manner. The later Florida MkIV Monorail used this technique extensively.
A welded low carbon steel frame could carry the body, load and side wheel suspension, and all the equipment. The frame consists of (6) main weldments bolted together with expanding bolts. This makes the frame behave as one solid chunk while making each weldment much easier to fabricate. To get the most life from the weldments, they were stress relieved before final bolt hole machining.
Today I look back at the way we engineered the MkIII Monorail in 1966 and wonder if I'd have the courage to design it that way today. Only one part ever got stress analyzed; the side suspension arms, since they were a very tricky item to weld together. Everything else was designed "by eye", that is to say, if it looks right, it Œs probably right.....what famed aircraft designer Burt Rutan calls TLAR.....That Looks About Right. The rationale is that one should carefully observe great designs like nature-designed trees that resist wind, or bird bones that are absolutely the lightest structures and are very strong. Observe successful aircraft, race cars and sailboats.....you get the eye for proportion. Then when you get the design assignment for something new, you can sketch up the basic configuration right away. No time wasted doing calculations.
After assembling the first MkIII Monorail test train (minus the bodies) at Disneyland in 1968, we load tested the frames using a brittle lacquer technique which reveals any high stress locations. There were a few spots where we followed up with load cell tests that proved that these were only moderate stress levels. After the 12,000 mile test run, we built the rest of the cars, added the bodies, and placed the MkIII Monorails into service. New bodies were added to the original chassis during an overhaul in the late 1980's. I sure didn't think that this old Monorail chassis design would still be running at Disneyland and Las Vegas after almost (34) years with minimal fatigue cracking.
oOo
Next month: Sky Ride, WEDway, and New Astrojet
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-- 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 August 14, 2002
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