A Car-Builder's Dictionary

The Miller Hook

The passenger car coupler of preference before Major Janney did his thing.

Description: The Miller Hook was a semi-automatic coupler that replaced the link and pin for most passenger cars built after about 1870, though it was seldom used for freight cars. The “hook” was only one part of a system that combined a coupling device, a buffer system and an improved end platform to prevent the telescoping of cars when a train struck an obstacle. At the same time it eliminated the violent yanks that otherwise accompanied the excessive slack take-up with link and pin couplers: something that no doubt helped make it a standard on passenger cars.

Carson & Colorado Business Car #10

Carson & Colorado business car #10 With Miller Hook coupling.

Below we present three drawings from Miller’s patent application. The complete description, with drawings, can be found at the United States Patent and Trademark Office Home Page under U.S. Patent #56,594, dated July 24, 1866. Similar drawings may be found at Forney-359/61.

The first drawing shows the mechanism from the bottom, looking up at the floor of the car. Because of this, the hook looks like a right hand with the fingers crimped. But when viewed from above, it is actually like a left hand with the fingers crimped.

Miller Hook Patent Drawing, Top View

(Click pic for enlargement.)

The hooks are held against each other partly by springs, and partly by the acute angle of their mating surfaces. The buffers hold the cars apart, maintaining tension against the mating surfaces. When the buffers are compressed, as when one car is abruptly shoved against the other, the hooks can be separated by a brakeman standing on the car’s platform thrusting against a lever connected to the hook by a short chain.

Miller Hook Patent Drawing, End View

The third drawing shows how the hook and buffer are positioned beneath the platform to simultaneously hold the cars together and hold them apart.

Miller Hook Patent Drawing, Side View

History: For most of the nineteenth century, the link and pin coupler was the standard coupler used to hook together freight cars. It consisted of a tube-like body that received an oblong link. During coupling, a brakeman had to stand between the cars as they came together and guide the link into the coupler “pocket.” Once the cars were joined, a pin was inserted into a hole a few inches from the end of the tube to hold the link in place.

The link and pin coupler, though widely used, ultimately proved unsatisfactory.

1. It made a loose connection between the cars with too much give and play.
2. There was no standard design and train crews often spent hours trying to match pins and links while coupling cars.
3. Links and pins were frequently lost, resulting in substantial replacement costs.
4. Crew members had to go between moving cars during coupling and were frequently maimed and sometimes killed. A missing finger or two was evidence of a brakeman's “experience” at his trade.

Little progress was made at solving the coupler problem until inventors totally discarded the old technology and applied fresh and original thinking. One who did this was Col. Ezra Miller.

Miller was born at Bergen, New Jersey, in 1812 and educated as a civil, topographical and mechanical engineer. At 21 he enlisted in the 2nd regiment horse artillery of the New York militia, where he obtained the rank of full colonel after ten years. He married at 29, and settled at Fort Hamilton, NY. In 1848 he moved his family to Rock County, Wisconsin, where he was employed in the survey of state lands for the new state of Wisconsin, and also as a farmer. Following these early years with the state survey, he engaged in railroad survey and construction work with the Chicago & North Western Railway Co. In 1851 he was commissioned a colonel in the Wisconsin militia, and in 1852 he was elected to the Wisconsin Senate, serving one term.

While employed by the C&NW Railway in 1853, Colonel Miller became interested in improving the existing methods of coupling railroad cars. For some ten years he studied and experimented with this problem, obtaining a patent on a semi-automatic passenger car coupling system in 1863. Continuing his studies, he improved on his basic idea and obtained two more patents, one in 1865, and another in 1866.

Miller’s inventions were more than simply a coupler, but a combined passenger car platform, coupler, and buffer design, generally referred to as the “Miller Platform.” He began with a stronger end platform, moved up and made an integral part of the coach's frame to better transfer axial motion through the cars when starting, stopping, or operating the train. Mounted below the platform was a combination of semi-automatic coupler (the “hook”) and buffer, assuring tight connection between cars and providing a system to absorb the end impact forces between the cars.

Miller was not the first to come up with a hook-type coupler, but he did manage to work out the engineering details and successfully market a device that the railroad industry would accept -- accept, that is, for passenger equipment.  The Miller Hook had become a national standard on passenger cars by about 1875, but it was rarely applied to freight equipment. Poor-324 says the Colorado Railway Commission Report for 1885 said the Miller automatic coupler was standard equipment for all passenger cars of the Denver South Park & Pacific as of that date.

Why didn’t the railroads simply apply Miller Hooks to the freight car fleet?  It was a known and tested mechanism. Thousands were in daily service.  There was nothing strange or unproved about it.  Maybe it was the cost; Miller's royalty fees were fairly stiff. Maybe the buffer arrangement could not be made to fit under the ends of a freight car unless platforms were added. It is more than likely that the Miller Hook was simply considered obsolete by 1885, its technology having been replaced by that of the new knuckle-type couplers (Janney got his first patent in 1873).

So far as we know, the South Park and its successors kept using the Miller Hook on their passenger equipment until replaced by the Janney knuckle coupler sometime around the turn of the century.

Miller’s Patents

Pat. No. Date Description
38,057 31 March 1863 Basic coupler and its draft gear
46,126 31 January 1865 Improvement in coupler design, together with buffer
56,594 24 July 1866 Improvement in coupler design and buffer, together with platform

We are aware of just three railway groups that have restored one or more passenger cars with Miller couplers.

1. In the mid-1980s, the Nevada State Railway Museum at Carson City, Nevada, completed restoration of Virginia & Truckee coach #4 with Miller couplers.
2. In 1999, the Society for the Preservation of Carter Railroad Resources (SPCRR) at Fremont, California, completed restoration of Southern Pacific combine #1010 with Miller couplers.
3. In 2002, the Mid-Continent Railway Museum at North Freedom, Wisconsin, completed restoration of Milwaukee, Lake Shore & Western coach #63. The next page tells their story (with photos).
11 April 2006

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