How did we come to the point of having two different knuckle designs allowed in the construction coupler systems for freight cars?
With the influx of newer employees, both the Train & Engine service as well as new Car Dept. employees - they both have trouble recognizing the differences and will spend hours trying to make the wrong knuckle work.
I do not know the answer to your question. That was a decision of the AAR Couplers and Draft Grear Committee (name many have changed from time to time or I am mis-remembering) Since the type is cast into the shank and the knuckle it sounds like the company is not training new hires very effectively OR they can not read. I suspect it is a training issue.
Mac McCulloch
My understanding from those in the field - the casting identification, while there is not conspicuous and is not in a easily viewed location. Additionally, there is not a significant visual distinction between the two. Brakeman’s lanterns in the middle of nowhere are not the best lighting equipment to view subtle visual cues and difficult to read casting marks.
I had a train last night spend 5 hours as the crew and a car inspector that was on the scene attempted to fit the wrong knuckle to a car. At the one hour mark, I communicated to them that they must be trying to use the wrong knuckle - but I am just a disembodied voice over a communication channel miles away from the scene. While I have no fear that better training is part of the answer; the real question is WHY the AAR thought there needed to be two varieties in the first place (I only wish I could drag those who made that decision out in the middle of nowhere at 0 dark 30 and command that they now change the broken knuckle before them!).
Modern railroad equipment has always been about standardization. To decree that there are two varieties of knuckles that are not interchangeable on a individual coupler defeats the whole idea of standardization. Murphy was a railroader when he formulated his law!
I didn’t know the knuckle itself had the designation on it. I was taught the E knuckle had the rounded shank, that looked like a lower case e. The F had a squared off shank, like the capital letter F.
Sometimes the designation on the coupler itself can be confusing sometimes. I forget how some read and I don’t have one handy to look at, but designations something like EF60, where both letters appear. At least you have a 50% chance of being right if you don’t know. (It’s the first letter that governs.)
Even if crews know what kind they need, they go to the locomotive and just go by the E or F marking on the knuckle holder. They don’t bother to look too closely at the actual knuckle itself, just assume that the E holder has an E knuckle in it, etc. It doesn’t just happen to new hires, either. Old heads with 20+ years sometimes have that bad habit. (I have some experience with this when a train stopped to help and the old head went to get the knuckle of his engine.)
Jeff
The more I think about why E and F knuckles are not interchangeable, the more I think the E and F knuckles were deliberately designed not to be interchangeable.
IIRC the draft limit for E couplers is 250,000# and the F is 350,000#. In both cases the knuckle is deliberately designed to be the part most likely to fail on the theory that it is much easier to replace a knuckle than a drawbar or drawbar and yoke combination. Plus, odds are running over a drawbar is likely to cause a derailment.
F couplers are used, and probably required, on “unit train” type equipment, stack cars and coal cars. I would not be surprised to find that all new cars require F couplers, but I do not know that. The F coupler allows heavier trains to be operated than E couplers, everything else held constant.
Putting a F knuckle in an E coupler defeats the knuckle fail first policy. Putting an E knuckle in an F coupler means that it is highly likely to fail soon, maybe on the first pull.
Mac
As Jeff stated, F has a fairly straight flat back at the shank, the E has a rounded curve on the shank.
The F fits the shelf and Tight Lock couplers; the E fits just about everything else.
Both are clearly marked with a stamping, and are not that hard to tell apart.
I think what is happening is the new hires simply are not told there is a difference; it’s one of those “learn it on the road” things I guess.
The reason the F has a flat back is because the tight lock coupler is a self-centering coupler, and the flatter design helps lock the knuckles and keeps the forces straight line, and the F couple has less gathering swing than an E type.
The E can pivot more, but will also twist out if placed under enough force.
The quickest way to tell is to go look at the knuckle on the other end of the car. The knuckle type is embossed right on top of the knuckle in plain sight. Only once did I see a car with two different types of couplers.
Don’t forget the H111 knuckle. It’s interchangeable with an F, but a lot stronger.
Dick Haave
The rotary equipped coal hoppers/gons are equipped with F knuckles. I know I’ve seen a list, either on here or in Trains itself, of other cars that use them. Mostly more specialized types because the F draft gear is more expensive to use.
Is it the coupler type or grade that is differently rated? I have a little chart (a quick reference guide for converting amps to tractive effort when starting) that I carry, but it’s in my locker and I’m on vacation. It shows a difference in grade of knuckle, but it’s not by knuckle type. I think that all of the well cars for stack trains still have E couplers, as do the locomotives and most other equipment.
Admittedly, I don’t see the couplers as close up as I used to. Ed and others are in a better position to see them up close on a daily basis.
Jeff