couplers pins, underslung vs overslung

[TH&B]

When pulling the pin to uncouple cars why are all newer cars under slung but all locos and some age old cars over slung? On some old cars the top of the Knuckle has been welded shut and replaced by under slung. I also notice that half moons damage the under slung operating lever when shoving to block. I also notice that damaged under slung levers can drag on the ground and even uncouple cars unintentionaly. Exept for cars with end loading what is the advantage of the under slung operating lever pin? (other than using it as a step for riding the point..... oops) If the over slung design is indeed out dated for some reason, why do all new locomotives have them??

[edblysard]

Part of the reason is where you stand to un-couple a locomotive, and where you stand doing the same to a railcar.
On a locomotive, if you used a underslung or bottom hung pin, you would have to stand on the ground to operate it, as it is designed now, you stand on the bottom step, the cut lever top loop is waist high then.
Note most also have a long end on the locomotive cut lever, that will allow you to uncouple from the ground, but it is a lot harder to use.

On a locomotive, you almost always have to hold the lever back/ up until the couplers seperates from each other , gravity holds the pin down, by way of the desing on the cut lever, note it always leans forward, the leverage from the top heavy lever holds the pin down and in place, along with the internal design, to operate it, you have to pull it back, not up, and the leverage created lifts the pin, let go, and the leverage from the cut lever shoves it back in place, locking the coupler.

To un-couple a railcar, you have to be standing on the ground, and all you have to do is lift the lever up as the slack is bunched up, the coupler is designed with a internal catch to hold the pin up once you lift it, and you can let go of the lever, allowing you to kick cars.
No slack, or stretched out, and it is designed so you cant lift it at all.
Both styles use gravity to work in favor of the coupler not coming undone, almost a designed in failsafe.
Both are designed to not function unless there is slack in the couplers.

Both styles, underslung and overslung, require you to lift the pin up.

A underslung coupler pin on a locomotive would receive damage often, and, due to the wide side to side swing most locomotive drawbars have, would require a complicated lever, with a lot of moving parts, similar to thoses on cushion drawbar cars, where the lever telescopes with the side to side play, just one more part to fail.
Because the pin on the locomotive is lifted from the top, a simple bail hanger does the same thing allowing side to side swing, but with less parts.

As for damage to the lever, that is caused by industries using the lever as a handy pull point to move cars around inside their plants, along with the hand brake wheel.
Yeah, sounds dumb, but they do it all the time.
As for the half moons?
Not real sure what your mean.
If you are referring to shelf couplers, with either a bottom shelf or lip, of both top and bottom shelf, that has no bearing on damage to the cut lever, its either caused by what I described above, or at some point, the knuckles were not aligned correctly, and they bypassed each other, and bent the lever.
You can hang them up pretty good that way.

There are two basic couplers on cars, type E and type F, type E can have no shelf,(standard E) or top and bottom shelf(SE), or bottom only shelf (SBE).

Type F couplers have a interlocking device, or teats that match the face or cuts on each other, to prevent the couplers from having any up or down slip at all when coupled to another F type.

E couplers without the shelfs are what most people think couplers look like, but they too, have a device, the shelves, to prevent them from riding up or over each other.

A shelf coupler (SE or SBE) will prevent this from happening, even if it is coupled to a non-shelf (standard E) coupler, or a F type, the shelf limits the up and down movement.

In any instance, the coupler itself, if aligned correctly when making a joint, will not cause damage to the cut lever.

Only part of the explaination, I am sure there is more to it...

Stay Frosty,
Ed

[mvlandsw]

Originally posted by 440cuin

On some old cars the top of the Knuckle has been welded shut and replaced by under slung.


The type of uncoupling lever or cut lever was probably not changed. The coupler casting used to come with provisions to use either type. If the top opening was not used a sheet metal stamping was welded over the hole. I have seen some lately with a more permanent welding job. When I worked in the Union railroad car shops I had to replace many of the sheet metal covers.

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