Kadee minimum body box widths


bnsd45
 

Has anyone on list ever done math to determine the minimum Kadee coupler box width needed to adhere to 18" radius curves yet allow use of Kadee couplers?  I know there are a series of variables, but an enterprising engineer could figure that out - Mr Storzek?

Variables I can think of:
- what car is coupled to
- length of car
- distance from Kadee pivot to truck center
- distance of Kadee shank

With the Kadee whisker couplers, box widths could become more narrow.  Of course, the pivot point being so far back with long shank precludes using significantly smaller boxes which is why Accurail designed a new coupler box with shorter shank.  Another concept is the option of a shorter shank Kadee whisker I suppose.

I noted Jon Cagle's Southern Car & Foundry Standard tank cars have nice narrow boxes and use of Kadee whiskers.

Any mathmeticians out there?

David Lehlbach


Rich Yoder
 

My quick measurement shows a Kadee at 7/16
The standard Draft gear box that I sell are 5/16 and I'm sure that could
be narrower. If you can find one of my USRA Gondolas those were even
narrower.

Sincerely, Rich Yoder
7 Edgedale Court
Wyomissing PA 19610-1913
610-678-2834 after 6:00PM est until 10:00PM
www.richyodermodels.com

-----Original Message-----
From: STMFC@yahoogroups.com [mailto:STMFC@yahoogroups.com] On Behalf Of
David Lehlbach
Sent: Saturday, February 21, 2009 8:49 AM
To: STMFC@yahoogroups.com
Subject: [STMFC] Kadee minimum body box widths

Has anyone on list ever done math to determine the minimum Kadee coupler
box width needed to adhere to 18" radius curves yet allow use of Kadee
couplers?  I know there are a series of variables, but an enterprising
engineer could figure that out - Mr Storzek?

Variables I can think of:
- what car is coupled to
- length of car
- distance from Kadee pivot to truck center
- distance of Kadee shank

With the Kadee whisker couplers, box widths could become more narrow. 
Of course, the pivot point being so far back with long shank precludes
using significantly smaller boxes which is why Accurail designed a new
coupler box with shorter shank.  Another concept is the option of a
shorter shank Kadee whisker I suppose.

I noted Jon Cagle's Southern Car & Foundry Standard tank cars have nice
narrow boxes and use of Kadee whiskers.

Any mathmeticians out there?

David Lehlbach





[Non-text portions of this message have been removed]



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Denny Anspach <danspach@...>
 

The Achilles Heel of prototypically narrow coupler boxes is that they inherently limit coupler swing, more if the shank pivot point is long, less if the pivot point is short. IMHO, this fundamental fact is what has held up companies otherwise favoring prototypical accuracy (such as Kadee) from moving in with all fours to adopt this naturally- attractive alternative. Less understandable in this mix is the continuing general tendency of suppliers to be overly solicitous only to those still dwelling in a dwindling HO modeling world of very short track radii.

The "Kadee Box" should be more accurately termed "Athearn Box" inasmuch as Kadee pragmatically adapted their coupler to the Athearn box of the '50s, which they judged at the time to be the de facto predominant installed-base coupler box . About a year or so ago, a review of couplers in one of the magazines judged a narrow box semi- scale coupler "unsatisfactory". When I challenged the author on his data behind this conclusion, I learned that all testing was performed only on sharp track 22" radius or less, a not-unexpected finding by itself, but totally misleading for so many of those pursuing the prototype modeling inherent with larger radii!

The attractive narrow coupler box within Jon Cagle's wonderful resin tank car kit (adapted to a Kadee #78) comes with a price: the long shank of the #78 coupler, further limited by the narrow box opening, * severely* limits the coupler swing. In this regard, this is not a model that would usually be attractive to most who will be favoring 18" curves. For those favoring such short radii in a prototype setting, e.g. industrial trackage, you may have problems, especially if two similar cars are to be coupled together.

As far as coupling/uncoupling on these curves with such cars, the operator may well have to manually center the couplers, just as in the prototype.

IMHO, this is just another area where the ongoing search for the "prototype" in appearance and operations should be moving us to adjust our thinking: e.g. advocating that the sophisticated models and accessories that we so favor, also be aimed to something well above the least common operational parameters.

Denny






Denny S. Anspach MD
Sacramento


Richard Hendrickson
 

On Feb 22, 2009, at 9:37 AM, Denny Anspach wrote:
IMHO, this is just another area where the ongoing search for the
"prototype" in appearance and operations should be moving us to adjust
our thinking: e.g. advocating that the sophisticated models and
accessories that we so favor, also be aimed to something well above
the least common operational parameters.







Yes, and fortunately the manufacturers are beginning to adjust their
thinking as well (e.g., Kadee). The gulf continues to widen between
serious scale modelers and toy train buffs. As you aptly point out,
hardly anyone on the STFC list is interested in trying to couple and
uncouple freight cars on 18" - 22" curves. Though there is at least
one model railroad publication that hasn't caught on yet, the days of
perpetually re-inventing Plywood Pacific layouts on ping-pong tables
are long gone.

Richard Hendrickson


Kurt Laughlin <fleeta@...>
 

----- Original Message -----
From: Richard Hendrickson

Though there is at least one model railroad publication . . .
----- Original Message -----

These days, that's what - about 25% of the industry?

KL


Richard Hendrickson
 

On Feb 22, 2009, at 3:05 PM, Kurt Laughlin wrote:

----- Original Message -----
From: Richard Hendrickson

Though there is at least one model railroad publication . . .
----- Original Message -----

These days, that's what - about 25% of the industry?









Actually, more than that, Kurt, since it's the publication with the
largest (though steadily declining) circulation and also, with a
couple of notable exceptions, the least prototype-modeling-oriented
editorial staff.

Richard Hendrickson


Anthony Thompson <thompson@...>
 

Richard Hendrickson wrote:
Yes, and fortunately the manufacturers are beginning to adjust their thinking as well (e.g., Kadee). The gulf continues to widen between serious scale modelers and toy train buffs. As you aptly point out, hardly anyone on the STFC list is interested in trying to couple and uncouple freight cars on 18" - 22" curves.
Get a grip, you mainline guys. Industrial trackage is often very sharp radius, and what may be a sound position--avoiding mainline curves in HO below 30 inch radius--cannot serve in many switching situations, including those accurately copied from the prototype. Just to cite one recent published example, consider Bob Smaus's LA industrial trackage.
But the prototype wrestles with drawbar centering in those situations, too. I must say I rather enjoy the occasional need to manually center couplers in Otis McGee's tight Dunsmuir yard (far enough from toy trains for you, Richard?).

Tony Thompson Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705 www.signaturepress.com
(510) 540-6538; fax, (510) 540-1937; e-mail, thompson@signaturepress.com
Publishers of books on railroad history


Richard Hendrickson
 

On Feb 22, 2009, at 4:05 PM, Anthony Thompson wrote:

Richard Hendrickson wrote:
Yes, and fortunately the manufacturers are beginning to adjust their
thinking as well (e.g., Kadee). The gulf continues to widen between
serious scale modelers and toy train buffs. As you aptly point out,
hardly anyone on the STFC list is interested in trying to couple and
uncouple freight cars on 18" - 22" curves.
Get a grip, you mainline guys. Industrial trackage is often very
sharp radius, and what may be a sound position--avoiding mainline
curves in HO below 30 inch radius--cannot serve in many switching
situations, including those accurately copied from the prototype. Just
to cite one recent published example, consider Bob Smaus's LA
industrial trackage.
But the prototype wrestles with drawbar centering in those
situations, too. I must say I rather enjoy the occasional need to
manually center couplers in Otis McGee's tight Dunsmuir yard (far
enough from toy trains for you, Richard?).




















Points well taken, and of course industrial trackage can be, and has,
been modeled with great accuracy by Bob Smaus and others. However,
whereas manual coupler fiddling goes with that territory, it's
undesirable in main line situations and absolutely unacceptable in
relatively inaccessible staging yards, where even 30" r. curves in HO
are way tighter than on the prototype.

Richard Hendrickson


sparachuk <sparachuk@...>
 

--- In STMFC@yahoogroups.com, "Kurt Laughlin" <fleeta@...> wrote:

----- Original Message -----
From: Richard Hendrickson

Though there is at least one model railroad publication . . .
----- Original Message -----

These days, that's what - about 25% of the industry?

KL
I have to say I'm mystified by the idea that #78 couplers don't work
on 22" curves. When I worked in a hobby shop our store window layout
had 22' and 18" radius curves. I regularly brought in cars I had
equipped with #78s and they never caused any trouble. Mind you, the
trains just went round and round but they never derailed.

Stephan Parachuk
Toronto


Richard Hendrickson
 

On Feb 22, 2009, at 5:54 PM, sparachuk wrote:>
I have to say I'm mystified by the idea that #78 couplers don't work
on 22" curves. When I worked in a hobby shop our store window layout
had 22' and 18" radius curves. I regularly brought in cars I had
equipped with #78s and they never caused any trouble. Mind you, the
trains just went round and round but they never derailed.







Round and round isn't the problem. Stephan. It's getting them to
couple and uncouple reliably. And of course, as Tony Thompson points
out, that isn't really a problem if you have easy access to poke and
prod with your uncoupling skewer, since having to open knuckles and
align couplers was entirely prototypical on tight radius curves. It
only becomes a problem when you're trying to couple and magnetically
uncouple cars on tight radius track that's difficult or impossible to
get to. But for some modelers that can be an issue.

Richard Hendrickson


Dennis Storzek
 

--- In STMFC@yahoogroups.com, Richard Hendrickson <rhendrickson@...>
wrote:

Round and round isn't the problem. Stephan. It's getting them to
couple and uncouple reliably. And of course, as Tony Thompson points
out, that isn't really a problem if you have easy access to poke and
prod with your uncoupling skewer, since having to open knuckles and
align couplers was entirely prototypical on tight radius curves. It
only becomes a problem when you're trying to couple and magnetically
uncouple cars on tight radius track that's difficult or impossible to
get to. But for some modelers that can be an issue.

Richard Hendrickson
I want to add some comments, and Richard's message is as good an intro
as any.

Coupler swing issues are closely related to both minimum radius and
coupler overhang, that is the truck kingpin to coupler dimension of
the different equipment that is expected to couple together.

If all you want to do is run a fleet of freight cars with the common
5'-6" kingpin to striker distance, you could probably glue Kadee
couplers (either size)rigidly on the car center line; no box needed at
all. The Kadee knuckle profile has much more clearance than the
prototype, and there is enough wiggle room for them to accommodate any
curve the cars can negotiate. They may not couple and uncouple
reliably on the tightest curves, but neither do the prototype.

A problem occurs when you introduce equipment with a longer coupler to
kingpin distance. Four axle steam loco tenders typically present the
same geometry as a freight car at the end of their tender, but the
coupler on the pilot beam displaces much further on curves. The
couplers on four axle diesels displace much further toward the outside
of a curve than the couplers on freight cars, and the couplers on six
axle diesels are worse yet. In order to stay coupled, the coupler on
the locomotive needs to swing far toward the track centerline, but
most people who want close to prototype dimensions on their freight
cars also want the same on their locomotives, so this limits the shank
length and swing available in the locomotive coupler. When the coupler
on the locomotive reaches the end of its swing, the coupler on the car
coupled to it will actually swing toward the outside of the curve in
an attempt to stay coupled to the locomotive. If there is not enough
swing, the couplers will drag the car off the track toward the outside
of the curve.

If you don't really know what sort of equipment or curves you need in
the future, it's best to stick with the dimensions that the
manufacturers have developed over the last half century; Kadees or
clones or Accumates in standard width boxes. If you want closer to
scale appearance of equipment, be prepared to be limited to closer to
scale (larger) radius curves. 18" radius in HO scale is equivalent to
a 130' radius curve; this is close to the minimum curve used on the
Chicago elevated system, and while electric locomotives with short
wheelbase trucks and wide swing couplers can handle freight cars on
curves this tight, it's unrealistic to expect a six axle SD-7 to do
so. This holds true for use of the semi-scale couplers as well;
Accumate PROTO:HO, Kadee 78, and Sergent scale working knuckles in
semi-scale draft gear all have somewhat less swing than the good ol'
Kadee No.5, and will require some testing to determine what the
minimum radius for reliable operation with the intended motive power
will be before designing the layout. My own personal standard is a
minimum 24" radius and number 5 turnouts for industrial trackage; this
allows trouble free switching using the pilot couplers on the small
steam that I run on locals, and the engines look so much better on
these broader curves.

Dennis


sparachuk <sparachuk@...>
 

--- In STMFC@yahoogroups.com, Richard Hendrickson <rhendrickson@...>
wrote:


Round and round isn't the problem. Stephan. It's getting them to
couple and uncouple reliably. And of course, as Tony Thompson points
out, that isn't really a problem if you have easy access to poke and
prod with your uncoupling skewer, since having to open knuckles and
align couplers was entirely prototypical on tight radius curves. It
only becomes a problem when you're trying to couple and magnetically
uncouple cars on tight radius track that's difficult or impossible to
get to. But for some modelers that can be an issue.

Richard Hendrickson
Richard: Sorry, I thought folks were expressing concern about the
running of the cars on small radii. It gives me cold chills to even
contemplate uncoupling/uncoupling on 18" radius curves!

Stephan Parachuk
Toronto


Denny Anspach <danspach@...>
 

The difficulty that I reported with the #78 Kadee coupler was NOT related to the coupler per se, but how with its relatively-long shank this coupler has a much reduced pivoting radius when it is prototypically and deeply inset into a prototypically-narrow box- as has been successfully done in Jon Cagle's resin tank car kits.

The #78 coupler (when in its native box) projects far beyond its striker plate than would be expected on the prototype. IMHO, Kadee has done this probably to ensure that the coupler will swing sufficiently to accommodate the short-radius market. The price paid for this is that the head sticks out -akin to the long neck of Ichabod Crane- and in the process expands the distance between cars, and also allows the gaping mouth of coupler box to be fully and quite visibly exposed in the process. If one is to focused on accurate prototype appearance, neither is acceptable.

If one is going to model couplers and their boxes close to, or in a prototype manner- and they look like it-, the following are reasonable and quite defendable goals:

1) Coupler head close to scale size.

2) Coupler face extends no more than 29/30" from striker face.

3) Coupler box is narrow, commonly the same width of the centersill.

There are varying and balancing operational tradeoffs when these standards are applied, but rather than denying reality, it is more honest to acknowledge that these are the issues to be debated (and perhaps the prices to be paid) if we are to continue pursuing prototype accuracy in all that we do.

OK, I am coming off my morning coffee high-

Denny




Denny S. Anspach MD
Sacramento


Steve Lucas <stevelucas3@...>
 

Here's an example of tight radius curves (about 12" in HO scale) on a
prototype, the CNJ's Bronx Terminal, as modelled by Tim Warris in HO
scale--

His home page--

http://www.bronx-terminal.com/?p=5

and the model--

http://www.bronx-terminal.com/?cat=8

Notice that standard freight cars were used, with no modification to
couplers or draft gear.

The PRR had many industrial tracks with 175' radius, using number 5
289/1000 turnouts to match this radius.

The problems with Kadee couplers on such tight radii are the use of
the centreing spring for delayed uncoupling, and shank length from
pivot to end of coupler box. If not using that spring, coupling
radius can be substantially reduced. But you'll often find yourself
swinging couplers to make a coupling on a layout.

Steve Lucas.




--- In STMFC@yahoogroups.com, Richard Hendrickson <rhendrickson@...>
wrote:

On Feb 22, 2009, at 5:54 PM, sparachuk wrote:>
I have to say I'm mystified by the idea that #78 couplers don't work
on 22" curves. When I worked in a hobby shop our store window layout
had 22' and 18" radius curves. I regularly brought in cars I had
equipped with #78s and they never caused any trouble. Mind you, the
trains just went round and round but they never derailed.







Round and round isn't the problem. Stephan. It's getting them to
couple and uncouple reliably. And of course, as Tony Thompson points
out, that isn't really a problem if you have easy access to poke and
prod with your uncoupling skewer, since having to open knuckles and
align couplers was entirely prototypical on tight radius curves. It
only becomes a problem when you're trying to couple and magnetically
uncouple cars on tight radius track that's difficult or impossible to
get to. But for some modelers that can be an issue.

Richard Hendrickson



[Non-text portions of this message have been removed]


Dennis Storzek
 

--- In STMFC@yahoogroups.com, "Steve Lucas" <stevelucas3@...> wrote:

Here's an example of tight radius curves (about 12" in HO scale) on a
prototype, the CNJ's Bronx Terminal, as modelled by Tim Warris in HO
scale--

His home page--

http://www.bronx-terminal.com/?p=5

and the model--

http://www.bronx-terminal.com/?cat=8

Notice that standard freight cars were used, with no modification to
couplers or draft gear.
But.... Look what they used for motive power.Those ALCO-IR-GE boxcabs
had relatively short wheelbase trucks, and no steps outside of the
trucks, giving them a kinpin to striker distance of about 7'-6"; not
hardly longer than a freight car. By contrast, an EMD SW-1200 has the
striker about 9'-6" from the kingpin (MR's drawing dimensions 9'-3" to
the end plate, the striker is several inches further out) and a GP-7
its about 11'-0". That's a big difference from a freight car, and it
will show up on tight radius curves as the locomotive couplet being
much closer to the outside rail than the coupler on the car.

In addition, I note that in early photos of CNJ 1000 (with the C.R.R.
of N.J. lettering) the locomotive has a short pined in knuckle, like
is used on a steam loco pilot beam, but later pix (1946) show this has
been changed to some sort of wide swing radial drawbar (not as wide as
on trolley freight power, but at least as wide or wider than a Kadee
No.5 box)so they must have found their crews were spending too much
time chaining cars.

The PRR had many industrial tracks with 175' radius, using number 5
289/1000 turnouts to match this radius.
24" radius in HO scale is 174 scale feet. That sounds like my layout;
24" radius and #5 turnouts.

Dennis


Richard Hendrickson
 

On Feb 23, 2009, at 12:37 PM, Gene Green wrote:
Richard,
I am sure that I have misunderstood your remarks quoted above but,
if I
haven't misunderstood, then I find myself a bit uncomfortable being
characterized as a "toy train buff" because of my 24" minimum main
line
radius. Your remark specifically stopped at 22 inches but I will have
to suffer with 21.5 inch passing siding radii in a couple of places.

In my case, and that of some others I am sure, there is a direct
relationship between income level and minimum radius. I have long felt
that I qualified as a "serious scale modeler" because of the
quality of
my research, my workmanship and my modeling prizes mostly received
from
the NMRA's PCR. All that serious modeling is now ended due to failing
vision and tremors.
















Well, Gene, you've established your credentials as a serious scale
modeler beyond question. And my generalization (over-
generalization?) certainly wasn't intended to rule out exceptions of
the kind you describe. Almost all of us have to make the best of
space limitations, some of them - as in your case - more severe than
others. So I guess I should re-state my point this way: serious
scale modelers, especially of main line railroads as opposed to weedy
branch lines and industrial trackage, avoid tight radius curves of
the snap track variety whenever they can, both for the sake of
appearance (cab forward malleys and 80' Pullman cars really do not
look good on tight radius curves) and for the sake of operation,
couplers being the example we've recently been discussing.

Richard Hendrickson


krlpeters
 

First of all, I have to mention that I have enjoyed belonging to this group, even thou I have not been on it that long. I have learned more in the last few months than in the previous years.
 
I fear that I am one of the few on this list that have to contend with 18 & 22" curves. It was either that or do without a layout at all. Am aware of the problems this decession is causing, but I feel they can be worked around.
 
Now if someone can just come up with a passable reason to include a NP ore car in my Upper Michigan iron ore drags.....
 
Thanks again for sharing your information with me.
 
Karl Peters 

[Non-text portions of this message have been removed]


Tim O'Connor
 

Gene

John Armstrong had a "5 degree" curve on his layout that
he told me was ideal for viewing a train. It was an inside
curve with a hilly background, and trains really did look
magnificent on it. Personally I think 24" is fine for an
industrial siding, but I would be loathe to use anything
less than 36" for a main track on an outside curve (like a
peninsula) but I think 30" can work for inside curves that
hide the overhang effect... But like you, I have no room
for a large layout. So I'm building a pt-to-pt shelf. I
may include a very large S "curve" -- like 120" radius. :-)

Tim O'

At 2/24/2009 10:49 AM Tuesday, you wrote:
Richard,
I overreacted. Sorry!

All,
Out of curiosity only, how many would agree that a 24" radius is OK?

How many don't agree and would have to insist on a broader radius?

For those having their layout in tight quarters has it been necessary
to establish a maximum length for freight cars? If yes, was the
decision made for operational or appearance reasons?

In my case, as I have already stated, I have to accept a 24" minimum
mainline radius and then go tighter from there for passing sidings,
yards, etc. For me that rules out the M&StL's Budd coach behind a
gas-electric but it also rules out any freight cars longer than the
P2K 53'-6" flat cars. I feel that limit is sensible for operational
reasons but still not good enough in the appearance department.

In anyone's opinion at what radius do broad curves become overkill?
36"? 48"? 60"?

My dream has always been to build a layout in a round barn. The
radius around the perimeter would be broad enough that it could be
regarded as straight.

Gene Green


Jack Burgess
 

Tim wrote:

Personally I think 24" is fine for an
industrial siding, but I would be loathe to use anything
less than 36" for a main track on an outside curve (like a
peninsula) but I think 30" can work for inside curves that
hide the overhang effect.
Well, I use 21" curves although I do have spirals between every curve and
the adjacent tangents. Curves on the prototype YV in the flatlands were
generally 4 degrees while those in the Merced River canyon were 10-12
degrees. They had nearly two dozen 13 degree (or shaper) curves including
three 17 degree curves and one 18 degree curve. A 13 degree curve is
equivalent to a 61" radius in HO. There is no way to fit even a 13 degree
curve into my layout...it would take 10 feet to accommodate a turnback 13
degree curve! And my layout room (once called a double-car garage) is only
20'x20'.

I think that we get used to seeing non-prototype curves on model layouts
and, as long as the equipment looks okay, we are not bothered by them. I
don't run passenger trains and the engines are all 2-6-0s except for a pair
of 4-4-0s which didn't get out on the mainline in the month/year that I am
modeling. In 1939, freight cars tended to be 40-footers although I do have a
couple 50-footers (which still look fine). I choose 21" curves in order to
provide the appearance of how the prototype YV traversed the canyon, one
curve after another. Visually, I think that it works. Operationally, it
isn't a problem...S curves without a long enough tangent is much more of a
problem.

So...we need to keep in mind that not everyone is running 4-8-4s.....<g>

Jack Burgess
www.yosemitevalleyrr.com


Tim O'Connor
 

Jack

Yes, you're right, I should have mentioned that since I
run coupled 90' freight cars (in modern mode) and cab
forwards (in steam mode) that a large radius is essential
for both appearance and operation.

Whenever I see a model passenger train whip around a 36"
curve in HO at 50 smph I imagine all the passengers being
thrown out of their chairs and beds...

Tim O'Connor

At 2/24/2009 11:33 AM Tuesday, you wrote:
Tim wrote:

Personally I think 24" is fine for an
industrial siding, but I would be loathe to use anything
less than 36" for a main track on an outside curve (like a
peninsula) but I think 30" can work for inside curves that
hide the overhang effect.
Well, I use 21" curves although I do have spirals between every curve and
the adjacent tangents. Curves on the prototype YV in the flatlands were
generally 4 degrees while those in the Merced River canyon were 10-12
degrees. They had nearly two dozen 13 degree (or shaper) curves including
three 17 degree curves and one 18 degree curve. A 13 degree curve is
equivalent to a 61" radius in HO. There is no way to fit even a 13 degree
curve into my layout...it would take 10 feet to accommodate a turnback 13
degree curve! And my layout room (once called a double-car garage) is only
20'x20'.

I think that we get used to seeing non-prototype curves on model layouts
and, as long as the equipment looks okay, we are not bothered by them. I
don't run passenger trains and the engines are all 2-6-0s except for a pair
of 4-4-0s which didn't get out on the mainline in the month/year that I am
modeling. In 1939, freight cars tended to be 40-footers although I do have a
couple 50-footers (which still look fine). I choose 21" curves in order to
provide the appearance of how the prototype YV traversed the canyon, one
curve after another. Visually, I think that it works. Operationally, it
isn't a problem...S curves without a long enough tangent is much more of a
problem.

So...we need to keep in mind that not everyone is running 4-8-4s.....<g>

Jack Burgess
www.yosemitevalleyrr.com