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coupler distance over car end

vapeurchapelon
 

Hello friends,

I have several cars where the coupling distance seems to be or definitely is too large, so I have to reposition the coupler box. I already use Kadee #153 couplers together with #178 box (where possible). My question is if there are any rules regarding the correct position = distance of coupler face over end beam or running board, or if I just could do as short as possible to be correct - just making sure that the coupler box front is gap-free with the end beam (which I doubt). Any help will be very appreciated.

Many thanks an greetings

Johannes
modeling the early post-war years up to about 1953

Dennis Storzek
 

Johannes,

You first need to determine where the center sills actually end. In North American practice in our era, the sills were typically capped by a massive casting known as the 'striker casting', its purpose being to receive the blow from the 'striker horn' on the coupler when under heavy impact, to keep the draft gear from being damaged. Rule of thumb for freight cars built after the mid thirties is this is 5'-6" from the truck kingpin. Most drawings and equipment diagrams dimension the truck centers, and most also dimension the length over strikers. Tabular data normally includes length over strikers. Note that the striker is usually several inches out from the end sill, but this dimension varies.

The ARA/AAR Type D coupler, in use from just before WWI, and the Type E, still the current standard, are 12" from 'pulling face', the inside of the knuckle, to the back of the striker horn. Steam era draft gear typically had 3" of traven, putting the pulling face 15" from the striker casting. Earlier MCB approved coupler designs were smaller, typically 9.25" from pulling face to striker horn, so cars so equipped couple closer together.

Dennis Storzek

vapeurchapelon
 

Hello Dennis,
 
wow! This is GREAT information which helps a lot! Many thanks!
One problem is that most brass cars don't have a coupler box already in place but just a cut-short at a non-defined place center sill instead, and several models obviously have the threads for the coupler box set at a wrong place...
 
Johannes
 
Gesendet: Dienstag, 03. März 2020 um 16:30 Uhr
Von: "Dennis Storzek" <destorzek@...>
An: main@RealSTMFC.groups.io
Betreff: Re: [RealSTMFC] coupler distance over car end
Johannes,

You first need to determine where the center sills actually end. In North American practice in our era, the sills were typically capped by a massive casting known as the 'striker casting', its purpose being to receive the blow from the 'striker horn' on the coupler when under heavy impact, to keep the draft gear from being damaged. Rule of thumb for freight cars built after the mid thirties is this is 5'-6" from the truck kingpin. Most drawings and equipment diagrams dimension the truck centers, and most also dimension the length over strikers. Tabular data normally includes length over strikers. Note that the striker is usually several inches out from the end sill, but this dimension varies.

The ARA/AAR Type D coupler, in use from just before WWI, and the Type E, still the current standard, are 12" from 'pulling face', the inside of the knuckle, to the back of the striker horn. Steam era draft gear typically had 3" of traven, putting the pulling face 15" from the striker casting. Earlier MCB approved coupler designs were smaller, typically 9.25" from pulling face to striker horn, so cars so equipped couple closer together.

Dennis Storzek

Edward
 

The back of the coupler head must be at least the distance of the draft gear spring travel to the striker plate on the end sill, about 3" to 4" or so.
Accurately modeled striker plates seem rare in all scales of  modeldom, with many installations relying on the Kadee coupler box lid tab to take its place.
The striker plate was a substantial steel casting against which the coupler head could press when forced, and not damage the car body end sill.

Photos CODECO and Erie 79000 show these castings riveted to the car's end sill.
Photo 394724366 shows a more modern update, in how striker plates are welded to the ends of their center sills. 
All show the same spacing between their faces and the back of the coupler head.

Coup03 shows the coupler mounting in a Duryea under frame.
Note the space between the back of the coupler head casting and the cracked striker plate on the center sill.
That space is about 3" to 4",  which was also common for cars having striker plates mounted to their end sills.
This striker plate face was damaged by too many hard couplings over the decades, being forced against the center sill carrier castings.
While the Duryea was a different type of underframe, couplers were mounted to it the same way as on other cars.

The tape measure shows a 6" space between that striker plate on the end of the center sill, and the center sill's end carriers on the car's end sill.
It measures 9" to the car' s end sheathing and end sill behind that.
This is 3", which is the thickness of those center sill end carrier castings.

On a Duryea underframe, the center sill is spring-loaded at the inner sides of the bolsters.
It slides back and forth under the car body upon impact.
The center sill travel has a 6" allowance at each end. 

The Duryea design reduced much of the stress from rough handling on the car body and its framing by isolating and spring-loading the center sill.
A major problem with it was the need for special tooling and skills to repair it, for which not all railroads were equipped to handle.
As Duryea under fames aged, increasing maintenance and repair work was required. They were banned from interchange service in the 1960's.

Ed Bommer
 

Dennis Storzek
 

On Tue, Mar 3, 2020 at 08:07 AM, vapeurchapelon wrote:
One problem is that most brass cars don't have a coupler box already in place but just a cut-short at a non-defined place center sill instead, and several models obviously have the threads for the coupler box set at a wrong place...
 
It's not just brass cars. Since ALL the couplers available to the hobby, except for the Kadee #711 "Old Time" coupler, the Sergent, and the PROTO:HO Accumate were/are oversize, there has always been two schools of thought as to where to place the 'coupler box' on the model, since this part really doesn't model anything that's on the prototype car. One school basically said to put the end of the box at the prototype striker location, leaving the oversize coupler to be the modeler's problem. The other school said to move the coupler box back, so the distance between coupled cars would be correct when using the commonly available couplers. The problem with that strategy is to move the pulling face of the knuckle back where it belongs, the projection of the box past the end sill disappears, which doesn't look right either. So, most plastic kit floors have the box end somewhere between those two extremes. Fortunately, today's scale size couplers come with their own boxes, so those who care can do their research and mount the box in the correct location. Of course, if you model the pre-WWI MCB era, you're back to the same problem of oversize couplers. The Kadee 711 is the right size, as it's their HOn3 coupler equipped with a longer trip pin, but it's not very pleasing to look at.

Dennis Storzek
 

Jim Betz
 

Johannes,

  I'm going to answer this from a different perspective.  First you need to
decide whether the car will be used on a layout.  If it will then the amount
of distance between the coupler face and the truck center can affect
how well the car will/will not operate thru curves.  Derailments are no
fun whether it happens only to you, to someone else, or only in one or
two places on only one or two cars.
  Most models,  including both kits and resin cars, place both the truck
center and the coupler box/mounting holes by using "NMRA standards"
which rarely are 100% protoypically accurate (never?).  Those standards
were developed a long time ago when operational reliability was the
primary goal.

  There are often similar issues with how high the car rides.  This one is
often hard to fix (time consuming) and affects coupler height as well.
Remember that all couplers on all cars on any railroad at any one
point in time were essentially -identical- in terms of coupler height.

  These are -your- decisions to make.  

  Often you can simply use a short shank coupler in the same mount
(box) and close up the distance easily and quickly - even that may not
be prototypical distance but it often results in a car that operates
well and is "more accurate" ... and doesn't look obviously wrong.

  Lastly there is the decision about what you want to do in terms of
prototypical accuracy - and balancing that against your time spent
and perhaps even on money spent.
                                                                                               - Jim

vapeurchapelon
 

Hello to all repliers,
 
please excuse the delay. Ed, Dennis, this is all great information again! Lots of thanks! Jim, all my models HAVE to run good to excellent, and as I mentioned some weeks ago when I linked a clip of my freight train shot at an exhibition, I am investing all the time needed (which unfortunately can be really "excessive" on some models with numerous or serious problems) to get them track very well, roll great, without wobbling, and of course with correct coupler height (plus lots of repairs, enhancements, detail corrections, etc...). Now with the necessary correction of the coupler box position on several cars it is even more work since the new thread - per Murphys rule - of course isn't far enough away from the current thread that one just could drill a new hole - no, I have to cut away the floor section and solder in a new one :-)))
 
Dennis, thanks for pointing out these two schools of thought. It seems that I am looking for or already doing a combination of both - but I am sure most will call it "weird" so I won't recommend but just mention it! As already written I am using the narrow coupler box from Kadees #178 (which in my eyes looks even better than the #262 narrow box), but I am inserting the short #153 coupler. Because I know that these "semi-scale" coupler heads still are oversized I file away some material from the coupler head back face (of course both atop and below the shank) to get the coupler move freely in the box. Of course that short coupler won't swivel side to side in that box as much as the recommended-size coupler - but still more than enough for operations on radii above 30" or so. Our standard at the FREMO is a minimum of 40" (and not very much less on sidings).
 
Interesting to learn about the problem with pre-WWI, fortunately I don't model that era (which nonetheless is VERY interesting, of course!)
 
Many thanks again to all who replied!
 
Johannes
modeling the early post-war years up to about 1953
 
Gesendet: Dienstag, 03. März 2020 um 20:17 Uhr
Von: "Dennis Storzek" <destorzek@...>
An: main@RealSTMFC.groups.io
Betreff: Re: [RealSTMFC] coupler distance over car end
On Tue, Mar 3, 2020 at 08:07 AM, vapeurchapelon wrote:
One problem is that most brass cars don't have a coupler box already in place but just a cut-short at a non-defined place center sill instead, and several models obviously have the threads for the coupler box set at a wrong place...
 
It's not just brass cars. Since ALL the couplers available to the hobby, except for the Kadee #711 "Old Time" coupler, the Sergent, and the PROTO:HO Accumate were/are oversize, there has always been two schools of thought as to where to place the 'coupler box' on the model, since this part really doesn't model anything that's on the prototype car. One school basically said to put the end of the box at the prototype striker location, leaving the oversize coupler to be the modeler's problem. The other school said to move the coupler box back, so the distance between coupled cars would be correct when using the commonly available couplers. The problem with that strategy is to move the pulling face of the knuckle back where it belongs, the projection of the box past the end sill disappears, which doesn't look right either. So, most plastic kit floors have the box end somewhere between those two extremes. Fortunately, today's scale size couplers come with their own boxes, so those who care can do their research and mount the box in the correct location. Of course, if you model the pre-WWI MCB era, you're back to the same problem of oversize couplers. The Kadee 711 is the right size, as it's their HOn3 coupler equipped with a longer trip pin, but it's not very pleasing to look at.

Dennis Storzek
 

Dennis Storzek
 

Just to finish this up, I'm going to post a link to the results of a search and see if it works:

Distance between coupled cars

Not exactly the same question but related there are some good comparisons made by Doc Denny back in 2005.

Dennis Storzek

vapeurchapelon
 

Thanks again Dennis,
 
at weekend I will go through these postings.
 
Johannes
modeling the early post-war years up to about 1953
 
Gesendet: Mittwoch, 04. März 2020 um 14:56 Uhr
Von: "Dennis Storzek" <destorzek@...>
An: main@RealSTMFC.groups.io
Betreff: Re: [RealSTMFC] coupler distance over car end
Just to finish this up, I'm going to post a link to the results of a search and see if it works:

Distance between coupled cars

Not exactly the same question but related there are some good comparisons made by Doc Denny back in 2005.

Dennis Storzek