22 inch radius

[Anonymous]

Looking at purchasing an engine.
It menrtions that a 22 inch radius is reccomened.
What exactly does that mean, that 22 inch radius is recommened.
Thanks for the help.[^]

[Javern]

22" radius is the sharpness of the curve, higher the number the wider the curve. Also larger the number the more room you need for track as the curve is spread out or wider.
Generally 18" are the minimums on layouts and many now are going to 22" and up to 30" or more curves. The wider curves make it easier to run the largest train cars and also looks more realistic.

[egmurphy]

It usually means that trying to operate the loco on sharper radius track can cause problems, most likely because the long wheelbase of the loco will cause the drive wheels to bind on sharper curves.


Regards

Ed

[Anonymous]

So 22 inch radius which is actually 7 inches in diameter is meant as 22 inch radius is actually meant as a 22 inch diameter.[?]

[Anonymous]

22" radius = 44" diameter.

[Anonymous]

44 inches wow, that is a large turn.

[Anonymous]

QUOTE: Originally posted by kevin robbins

...It menrtions that a 22 inch radius is reccomened...

That's the very minimum the locomotive can operate on reliably. However it will look better on a larger radius.
There are recommened practices or guide lines established by the National Model Railroad Association for different types of equipment and the track they can run on without problems.
This explains what standards and recommended practices means
http://www.nmra.org/standards/
This is the chart that list the different kinds of equipment and the track standards for them http://www.nmra.org/standards/rp-11.html

[Anonymous]

The BLI J1 2-10-4 requires 24" minimum and good trackwork. Even then the strain is noticable as it slows slightly due to the tension on the rods.

That is a 48" or 4 foot diameter curve.

[Anonymous]

22 " facilitates greater lateral truck swing.

[Anonymous]

All good information,thank you.

[ndbprr]

For what it is worth a 30" radius is the equivalent of a very tight industrial spur limited to about 10 mph operation. as you progress in the hobby your radius requirements will increase substantially. The layout I am building will have 48" radius with 60" the prefered radius on the mainline. I am also scratchbuilidng #12 turnouts in the mains which are limited to about 20 mph in real life.

[Don Gibson]

WHY 22'' radius?

BECAUSE Plywood comes in 4' X 8' sheets
BECAUSE 22" radius (44"d) is the largest curve that will fit on a 4X8 sheet
BECAUSE 4X8 track plans were published 50 years ago,
AND RR eauipment was smaller 50 years ago.

ENGINES got bigger and MODERN cars have gotten longer, BUT a sheet of ply hasn't, and beginners can nail track to a 4X8 board.

A 4x8 ''Layout is not small. It takes up a lot more room than 4X8. Like a pool table, one has to move around around it to play, and preoples arms are generally only 32" long.

3 4X8 board's in a 'U' configuation will use about the same floor space as a 4X8 and trains will take 3x longer to make a circle.

X X0
X
X XX
.... at least THINK about it for your 2nd layout.

[selector]

Model railroading is all about compromise, and manipulation of plans and designs.

How much constraint is there on the space you will have? Can you beg/shift something for a few more inches in space? Can you alter your imagined track layout? What can you do without..what are you absolutely not going to give up?

The answers to these questions will have a huge bearing on what you accomplish in achieving your goal of a working model/layout/track plan. As others have wisely said earlier, steam locos of a given set of fixed drivers, and most apssenger cars and longer modern rolling stock, do not do well on curves tighter than 22" radius. I have found this out personally, knowing beforehand that it would turn out to be the case by having read extensively on this forum. Diesels are less problematic.

Bottom line, if you really are stuck on space AND a given track layout, you may have to put up with radii shorter than 22". For your sake, I hope not; you will find yourself limited in what you can do, and run, on them.

Oh, and, yes, the larger radii do look more and more realistic as they grow.

Good luck. I (we all?) hope you have fun, no matter what.

And, we invite you back to ask other questions as you need to.

Cheers.[:)]

[Anonymous]

Thanks for all the in put. I appreciate the information.

[NZRMac]

Kevin, whats the loco you are looking to buy?

Ken.

[trainboyH16-44]

If you have the room, I would build a layout with 26" radius main line, #6 switces for the sidings, #5s in the yard, #4s on industrial spurs, 24" radius in the yard, and 18" radius on the spurs, if you don't have a layout already, or if it's still in the early stages.[soapbox][zzz]
trainboy

[Jetrock]

Radius: Distance from the center of a circle to its outer edge
Diameter: Distance from one outer edge to the other outer edge through the center. 2x radius.
Circumference: Distance from one point on the outer edge of the circle all the way around. Equal to circumference multiplied by the irrational number "pi", whose value is roughly 3.14159265... the value 22/7 is sometimes used but is not exact.

[Anonymous]

QUOTE: Originally posted by Jetrock


Circumference: Distance from one point on the outer edge of the circle all the way around. Equal to circumference multiplied by the irrational number "pi", whose value is roughly 3.14159265... the value 22/7 is sometimes used but is not exact.

I think you meant circumference = DIAMETER x Pi