John A. Miller

John A. Miller (born August John Mueller in 1872, Homewood, Illinois – died June 24, 1941, Houston, Texas) was an American roller coaster designer and builder, inventor, and businessman. Having patented over 100 key roller coaster components, he is widely considered the "father of the modern high-speed roller coaster." During his lifetime, he participated in the design of approximately 140 coasters and was a key business partner and mentor to other well-known roller coaster designers, Harry C. Baker and John C. Allen.

Miller was born in Homewood, Illinois and worked as a coaster builder at a very early age. At the age of 19, he started working with La Marcus Thompson and went on to serve as Thompson's chief engineer. By 1911, he was working as a consultant to the Philadelphia Toboggan Company He also worked with noted designers Frederick Ingersoll and Fred and Josiah Pearce.

Miller in 1910 designed a device that prevented cars from rolling backward down the lift hill in the event of pull chain breakage. It attached to the track and clicked onto the rungs of the chain. Known as the safety chain dog, or safety ratchet, it evolved into the device on the underside of cars that makes that distinctive clinkety-clank sound of wooden coasters.

Miller's most important contribution to coaster technology, though, was the underfriction wheel. In 1919, he patented the "Miller Under Friction Wheel," also called the "upstop wheel," which consisted of a wheel that ran under the track to keep the coaster cars from flying off. This allowed the designers to use very steep drops, sharp horizontal and vertical curves and high speeds. These are found on nearly every roller coaster in operation.

Besides patenting ingenious inventions for coasters—including several types of brakes and car bar locks—Miller built his share of unusual "scream machines." In 1920 Miller went into business with Harry C. Baker as "Miller & Baker, Inc." and over the next three years, they built popular coasters all over North America. Characteristics of their roller coasters are camelback hills (multiple straight or slightly angled drops that went all the way to the ground) and large, flat turns.

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