John Miller's Inventions

Miller's Safety Inventions

John Miller was a prolific inventor -- he held over 100 patents. Many safety devices used in today's coasters were invented by him. They include:

The Safety Chain Dog
The safety chain dog prevents the train from rolling backward if the lift chain breaks. Miller patented this ingenious device, which is the cause of the clanking sound heard when the train is pulled up the hill, in 1910.

Under Friction Wheels
Coaster cars have three sets of wheels: a weight-bearing set riding on top of the track; a set inside the track keeping the cars on course; and a third set -- the under friction wheels under the track -- locking the cars to the track. Miller was issued a patent for this brilliant invention in 1912. Miller's 1923 catalogue describes this innovation as follows:

The amusement-seeking-public of the present day desire more than a ride when patronizing the modern amusement park. They want speed, sensationally deep and thrilling dips and plenty of them, and Mr. Miller has solved the problem by catering to these most exacting desires in his new type of construction and cars.

This new type known as the MILLER Under Friction and Under Friction Locking Device is so designed and constructed as to permit of here-to-fore unheard of speed and apparently impossible steep, steep dips, with absolute safety, eliminating, as it does, the possibility of the cars leaping from the tracks, as would have been the case with the old type of construction and cars.

The new construction of cars is so designed as to permit of sharp, vertical and horizontal curves and extremely steep ascents and descents, rendering the thrills and sensations so much sought after by the present day amusement seeker, with the element of risk of accident removed, thus creating business far in excess of any previous years or precedent.

Another paramount feature of Mr. Miller's new designs, that immediately appeals to the Owner and Operator as well as to the public, is what is known as the Aero-Plane and Spiral Dips, which permits of steep ascents and descents on the sharp curves as well as on the straightaway, thereby making it practical to erect the new type of Deep Dipper on a much smaller area than was possible with the old type of construction.

More caution is required in designing the new type of construction in order to keep within the limit of centrifugal gravity, obtaining the sensational and thrilling dips demanded, yet not reaching that extreme which would pitch the passengers from the cars.

The importance of Miller's under friction wheels cannot be overemphasized. Without them there would have been no Golden Age of coasters and none of today's looping rides.

Click here for:

• A Miller biography
• Miller's coasters
• Miller's death
• The John A. Miller home page