Knuckle Coupler History and Analysis

softwerkslex · **Posted:** Wed Dec 24, 2014 10:07 am

Can anyone recommend some detailed and well researched sources on the development of the knuckle coupler and its adoption? Good articles or books?

Mr.Starr · **Joined:** Thu Jul 11, 2013 9:41 am **Posts:** 100

softwerkslex wrote:

Can anyone recommend some detailed and well researched sources on the development of the knuckle coupler and its adoption? Good articles or books?

You might want to check this link .. though you may have to scroll a bit .

http://en.wikipedia.org/wiki/Railway_coupling

Mr.Starr

Loco112 · **Posted:** Wed Dec 24, 2014 10:43 am

There is one book on the subject, its by National Steel Castings.

See if you can search and locate it, and if not, ill try to post a link in a few days.

David Johnston · **Posted:** Wed Dec 24, 2014 3:07 pm

John White's books, the American Passenger Car and the American Freight car would be a good place to look. Also the MCB Proceedings, starting about 1894 to about 1915 would be right from the horses mouth. The reading is a bit dry.

softwerkslex · **Posted:** Wed Dec 24, 2014 5:05 pm

Quote:

There is one book on the subject, its by National Steel Castings.

See if you can search and locate it, and if not, ill try to post a link in a few days.

Sounds interesting. Date? Title?

Brian Norden · **Posted:** Wed Dec 24, 2014 7:56 pm

David Johnston wrote:

John White's books, the American Passenger Car and the American Freight car would be a good place to look. Also the MCB Proceedings, starting about 1894 to about 1915 would be right from the horses mouth. The reading is a bit dry.

I will second the recommendation for the John White books -- especially the American Freight car book.

A few years ago I looked at some information about the couplers and what people considered as "automatic." I did a write up for the Southern Pacific Narrow Gauge Historical Society about the Sams coupler, which promoted itself as being automatic (actually maybe an improved link and pin), after one of the pins was found and it matched with one of the pockets used on the old Carson & Colorado.

Part of my write-up is the following:

Quote:

The modern knuckle coupler has its origins with the patent of Eli H. Janney granted on April 29,
1873. In 1877 he associated himself with the firm of McConway & Torley which produced and improved
the coupler. Mr. Janney continued to patent improvements to the coupler as late as 1912 – the year of his
death. In time the Master Car Builders Association adopted the term “vertical plane coupler” to identify it
in a generic manner. But, the M.C.B. was reluctant to adopt a design whose mating face patent was
controlled by one firm; in 1888 it reached an agreement with McConway & Torley that placed the mating
face design in public domain. The Master Car Builders Association then adopted the design as the
“M.C.B. Coupler.” During this period there were many other variants and improvements patented by
others. By the end of 1899 the M.C.B. had approved forty-nine manufacturers of the “vertical plane
coupler” that would work together.

The United States in 1893 enacted “Safety Appliance Act” and it became law on March 2, 1893. This
provided for application of automatic couplers, automatic brakes and common locations of grab irons on
railroad cars. The initial change over date was January 1, 1898, but this was extended to July 1, 1900.
The railroads were opposed to the required changes and the costs of doing these.

The law stated, “On January 1, 1898, it will be unlawful for a common carrier used for interstate
commerce to haul or permit to be hauled any car that is not equipped with couplers coupling
automatically by impact and which can be uncoupled without a man going between the ends of the cars.”

Ron Travis · **Joined:** Sun May 15, 2005 2:22 pm **Posts:** 1543

I would like to see such a book too. I know that there were many coupler variations throughout the link and pin era. I used to think that once the Janney was introduced, the coupler grew larger over time, but the principle remained the same. Now, I am not so sure about that.

dinwitty · **Joined:** Wed Oct 22, 2008 8:18 pm **Posts:** 2226

knuckle couplers? too many link and pin hand smashes, thats why....

Brian Norden · **Posted:** Wed Dec 24, 2014 11:53 pm

Ron Travis wrote:

I would like to see such a book too. I know that there were many coupler variations throughout the link and pin era. I used to think that once the Janney was introduced, the coupler grew larger over time, but the principle remained the same. Now, I am not so sure about that.

An MCB coupler of the 1890s will still mate with today's equipment. The mating faces are still the same -- it is just that the shank and coupler height got bigger. Over the years there had to be an ongoing compatibility. I have seen c1900 cars coupled to cars from the 1960s; but, the vertical size of the newer car's coupler overwhelms the the older coupler.

Ron Travis · **Joined:** Sun May 15, 2005 2:22 pm **Posts:** 1543

I am thinking that, over the time span of the automatic coupler use, there might be differences in the way that forces are transmitted through the relationship between the knuckle, knuckle pin, and locking pin. I would certainly like to see structural diagrams that illustrate those forces in all variations of the knuckle coupler.

Dennis Storzek · **Posted:** Thu Dec 25, 2014 2:05 pm

Actually, the interior contour underwent at least one major change during that time; illustrations of pre-Type D couplers show the "MCB contour", which had a very angular buffing surface inside the head. The ARA types D and E couplers use what is called the ARA (later AAR) "No. 10 Contour", which had an inner surface perpendicular to the car centerline. The No. 10 contour was designed to be backward compatible with the older MCB contour.

The thing that really distinguishes the different coupler designs that complied with the MCB was the geometry of the lock, and most were patented. Therefore the original patent documents would give the details you seek.

I've never seen one document that compares all the different designs directly, normally articles in the trade press of the day simply tell why the design being written about is "better" without making direct comparisons.

The Car Builder's Cyclopedia (formerly Car Builder's Dictionary) editions published during the introduction of the Type D tend to have a lot of illustrations of the different competing designs. I believe the 1919 and earlier are available on-line through Google books, while the 1922 is available on CD from an outfit called Rail Driver. That would be a good place to start.

Ron Travis · **Joined:** Sun May 15, 2005 2:22 pm **Posts:** 1543

Those patents on variations of the knuckle lock “pin” probably correspond to the variations that I referred to over time with the automatic coupler. My understanding is that originally, the knuckle was held closed by the lock pin bearing against the side of the knuckle tang to prevent the knuckle from rotating to open. This placed the knuckle pivot pin in the loading diagram when the knuckle was under pull during use. In other words, the knuckle pivot pin shared the loading with the knuckle locking pin.

Nowadays, I understand that the knuckle pivot pin bears no forces when the coupler is being pulled in a train operation. Instead of the knuckle locking pin preventing the knuckle tang from moving sideways to open during a pull; the knuckle locking pin prevents the knuckle from pulling straight out in line with the pull.

This takes the knuckle pivot pin out of the force transfer. As I understand it, the knuckle pivot pin can be missing and the knuckle will still remain closed and locked during pulling on the coupler. So the only function of the knuckle pivot pin is to prevent the knuckle from falling out when the knuckle locking pin is pulled.

David Johnston · **Posted:** Sat Dec 27, 2014 5:03 pm

A broken knuckle pin is a good indication that the lock and knuckle are worn excessively. When they are worn it lets the knuckle move outwardly loading the knuckle pin and frequently breaking it. Knuckle pin cotters are only required on rotary dump cars. New couplers are usually supplied with knuckle pin cotters to keep the pin from falling out in shipping. Knuckle pins were regularly stolen from cars in the train yard. We assumed they were taken as weapons, but never know for sure. If a train was all made up and ready to go it ran fine with out the knuckle pin. The first time anyone would notice the knuckle pin was missing was when the car was uncoupled and the knuckle fell out onto the track.

Loco112 · **Posted:** Mon Dec 29, 2014 2:14 am

Quote:

The first time anyone would notice the knuckle pin was missing was when the car was uncoupled and the knuckle fell out onto the track.

When the knuckle pin starts to get pulling and buffing stress it cracks and the pin will fall out of the bottom of the coupler. The head of the pin stays in place, on top of the coupler, to hid the danger. That is why you'll easily find a few headless pins laying in every rail yard.

With the pin missing, but the pinhead still in place, when you swing the knuckle open, it over rotates and comes out of the head just far enough to land on your foot. This occurrence breaks more feet and toes than any other railroad injury.

The steel toe of your boots will get bent down (front, back, middle, or all locations at the same time) and can come close to cutting your toes off with that injury too.

It has happened to the best of brakemen, so its something you have to think about when you reach for that 90 pound knuckle.

The crafty old brakemen look for the bottom of the pin in the daytime when they can see it, or assume its not got a pin in it at night.

Ron Travis · **Joined:** Sun May 15, 2005 2:22 pm **Posts:** 1543

Loco112 wrote:

Quote:

The first time anyone would notice the knuckle pin was missing was when the car was uncoupled and the knuckle fell out onto the track.

When the knuckle pin starts to get pulling and buffing stress it cracks and the pin will fall out of the bottom of the coupler. The head of the pin stays in place, on top of the coupler, to hid the danger. That is why you'll easily find a few headless pins laying in every rail yard.

With the pin missing, but the pinhead still in place, when you swing the knuckle open, it over rotates and comes out of the head just far enough to land on your foot. This occurrence breaks more feet and toes than any other railroad injury.

That seems like an unreasonable hazard. If the knuckle pin is not intended to carry any load, I would think it could be designed in such a way as to prevent it from inadvertently assuming any loading which will break it.

At what point in history did the knuckle pin become non-load-carrying?