Question: Who designed the rollercoaster train that involved underfriction?

Context paragraphs:
Roller coaster wheel assembly: Today's modern roller coasters, both wooden and steel, have the same basic design of wheel assembly.  Each wheel assembly has three wheels.  Underfriction, or up-stop, wheels; tractor, or running, wheels; and side friction wheels.  All of these help the train move safely and smoothly.

Underfriction: On a roller coaster train, the underfriction, up-lift, or up-stop wheels are a device to keep the train from jumping off the track under intense movement.  The design was patented in 1912 by John Miller.

Goliath (Walibi Holland): Goliath is a steel roller coaster located at the Walibi Holland theme park in Biddinghuizen, Dronten in the Netherlands.  It is described as "the fastest, highest and longest coaster in the Benelux".  It was mainland Europe's second Intamin "Mini Hyper Rollercoaster", so named as the ride is styled on the larger (generally over 61 m ) ride, but with a lower maximum height of 47 m .  The train travels at speeds of up to 107 km/h along 1214 m of track.

Maharajah Jungle Trek: The Maharajah Jungle Trek is a themed wildlife trail attraction at Disney's Animal Kingdom theme park at the Walt Disney World Resort in Lake Buena Vista, Florida.  It is in the Asia themed land, the Kingdom of Anandapur.  It shares this area with the Kali River Rapids white water raft ride and the Expedition Everest runaway train rollercoaster.

Castle Park (amusement park): Castle Park, formerly Castle Amusement Park, is a 25-acre amusement park and family amusement center located in Riverside, California.  The park utilizes a medieval "castle" theme and includes attractions such as a miniature golf course, arcade, and 27 amusement rides including three roller coasters such as "Merlin's Revenge", a junior rollercoaster, "Screamin' Demon" a spinning Wild Mouse rollercoaster, and "Little Dipper", a children's rollercoaster.  The main "castle" themed building, houses the arcade as well as its only dark ride; "Ghost Blasters", an interactive attraction, designed by Sally Corporation, which can also be found at other amusement parks throughout North America.  The park was designed, built and operated by Bud Hurlbut, who designed several rides at Knott's Berry Farm.  Castle Park is currently owned and operated by Palace Entertainment.

California Screamin': The boardwalk-themed launched roller coaster was designed by Ingenieur Büro Stengel GmbH and was built by Intamin.  California Screamin' is the eighth-longest rollercoaster in the world (and third-longest steel coaster in the United States), at 6072 ft long.  It is also the longest ride with an inversion (since Son of Beast became defunct).  Its highest point is 120 ft followed by a 108 ft drop.  Though built of steel, the structure as designed visually mimics the features of a wooden coaster.

Tilting train: A tilting train is a train that has a mechanism enabling increased speed on regular rail tracks.  As a train (or other vehicle) rounds a curve at speed, objects inside the train experience inertia.  This can cause packages to slide about or seated passengers to feel squashed by the outboard armrest due to the centrifugal force, and standing passengers to lose their balance.  Tilting trains are designed to counteract this discomfort.  In a curve to the left, the train tilts to the left to compensate for the g-force push to the right, and vice versa.  The train may be constructed such that inertial forces cause the tilting (passive tilt), or it may have a computer-controlled power mechanism (active tilt).

Carousel Gardens Amusement Park: Carousel Gardens is a seasonally operated amusement park located in New Orleans, Louisiana at New Orleans City Park.  It features many rides including an antique carousel, the Live Oak Ladybug Rollercoaster, and a miniature train that tours the park.  There are two new rides, a Ferris wheel and a drop tower called the Coney Tower.

Train (roller coaster): A roller coaster train is a vehicle made up of two or more cars connected by specialized joints which transports passengers around a roller coaster's circuit.

Woerden train disaster: The Woerden train accident was a railway accident on 21 November 1960 at around 20:10 in Woerden, the Netherlands near the "Cattenbroek" rail crossing.  The train involved in the crash, a DM80760 / Fac BD, was a British train from Hanover, Germany to Hook of Holland, the Netherlands with 151 furloughs including some 10 women and several children.  The train driver failed to notice a temporary speed limit.  The train rode too fast and crashed.  The train broke behind the second carriage and six of the eleven carriages derailed and tilted partially.  Two people died, three people were seriously injured and tens more received minor injuries.

Supporting paragraphs: Underfriction Train (roller coaster)
Answer: John Miller