How Small Radius Can An 0-4-0 Go?

The loco will negotiate a 15 inch radius curve. Froggy,

Without a trailing load it would go around something like a 3" radius. The limitation for your project will be coupling the stock together. The limitation for a (passenger) car comes when the trailing bogie is close to right angles to the leading bogie. Take the distance between bogie centers and that will be your minimum practical radius. (per car)

Robert wrote: [...]

[...]

The 0-4-0T Docksider will easily run on 12" radius, and has been known to negotiate 6" radius curves. Really!

Actually, with this engine, you should think more about the cars it will haul. Although 34ft cars will negotiate 12" curves, and run well on 15" curves, they look better on larger ones. You may have to increase coupler swing, though, as the back end of that lokey will swing amazingly far to one side as enters a curve.

Rule of thumb #1: use the largest radius curves you have room for.

RoT #2: a simple layout is better than a complicated one.

RoT #3: use easemenst (spirals) leading from straight to curve. This permits smaller radii than otherwise.

RoT #4: run the trains slo-o-o-owly. Less likely to pick rail joints, takes longer to traverse the layout, and looks better too.

Have fun!

...

Hmm, not quite. Flip your car upside down (the model, that is) and place the two trucks at right angles to each other. Now imagine a line through the center of each truck (parallel to the axles). If the car was on a piece of curved track, the center of the curve would lie at the intersection of these two straight lines. The radius of this curve (at its centerline) is the distance from the straight lines' intersection to the center of either truck; a straight line connecting the two trucks is the hypotenuse of a right triangle, with the curve radius as the legs.

There4, the minimum radius is (1/2 * d ^ 2) ^ (1/2), where d is the distance between the trucks.

At this radius, the force on the trailing truck is straight sideways. Theoretically, a 34' passenger car could be pulled around a 2 3/8" radius curve...but as the curve gets tighter, the pressure of the flanges against the rail increases, and on a curve that tight the wheel would probably climb right over the inside rail instead of following it.

I suggest you experiment. Tack some flextrack to a board and see how tight a curve will work well. I got a train with fairly standard equipment to go around a 9.5" radius HO curve... See this thread:

Cordially yours, Gerard P.

The problems with small radius curves ends up coupling the loco to the cars. Talgo trucks (the ones with the coupleers attached to the truck rather than the car body) will make the abliity of the train to take small curves a lot easier. If you really want small curves, the 3" radius or so can be done with specially selected equipment. I've seen a train running on a regular hat rim so take that as one possibility. I'd not wear the hat while the train was on the tracks as I can't hold my head that steady but there are those who can for a while. Have fun!

-- Why do penguins walk so far to get to their nesting grounds?

Why do you call bogie mounted couplers "Talgo"?

To me, "Talgo" refers to the Spanish designer and more normally to his design of single axle coach units which hook, one by one over the axle of the preceding unit.to form a low flexible unit train. Nothing in there to suggest a coupler mounted on the bogie!

Regards, Greg.P.

Dear Greg: The term's been used that way in model railroading for at least 30 years. (Robert Schleicher uses it in his MODEL RAILROADING HANDBOOK, for instance.) I don't know why, but sometimes with language it's better not to question too much.

Cordially yours, Gerard P.

Dear Greg: The term's been used that way in model railroading for at least 30 years. (Robert Schleicher uses it in his MODEL RAILROADING HANDBOOK, for instance.) I don't know why, but sometimes with language it's better not to question too much.

Cordially yours, Gerard P.

Many years ago, Varney produced the first "Dockside" (a particular B&O

0-4-0T, with two prototypes) model. It was the ancestor of all the hordes that followed, and Varney had an advertisement that featured a Dockside running around the rim of a HAT. It couldn't have been much more than 6" radius.

Dan Mitchell ============

The minimum possible radius is when the car starts acting like a turntable bridge (diameter of track circle equals truck spacing)!

Dan Mitchell ============

I don't know when it started, but the term was common when I was getting into the hobby over 40 years ago. Likely it began sometime in the mid

1950's, with the rise of cheap ready-to-run HO trainsets.

Dan Mitchell ============

Greg Procter wrote: snip

Long before they introduced the term Tyco to describe their ready-to-run line, Mantua marketed "tyco trucks". These were an early (or perhaps the first) version of truck mounted couplers. In the late '50s they also produced a model of the Talgo train. I cannot give a specific date, but, I believe these two terms may have been combined to produce "Talgo trucks" - a bit of nomenclature which has been with us for well over forty years. I hope this may be of some aid. Thank you. Jerry

>

That works for a vehicle with powered wheels, but not for unpowered. Even the theoretical minimum above won't (quite) work because the side forces on the flanges exceeds their guiding force.

The Spanish Talgo train prototype was reported in Popular Mechanics in 1949. Sounds like someone misunderstood the principles involved.

Regards, Greg.P.

The term "Talgo truck" is purely a US usage. The rest of us call them bogie or truck mounted couplers. I just wondered if there was some technology or logic I had missed.

Regards, Greg.P.

Thank you all for your wonderful information. I am going to use it all. And further to experiment with some track tacked down to a board. After all, its' only mid August (: next thing you know, Christmas will be here.

I really appreciate all the informative posts. And all the ways to look at and consider my proposed situation. And which are helpful, not only for this project, but for others. I hope to contribute to help someone else.

I was thinking of two track type plans: One an irregular "peanut" shaped loop, that would be all curves and no straights. And run diagonally across the 41" X 41" square space. The main fun would be the little town of lighted buildings and scenery, around the tree. And this would be conducive to slow running which would fit this tiny layout just fine.

And the other considered plan would be a "folded" figure eight, much like this one found at Thor Sheil's most wonderful web site (the fourth one down).

BTW do not miss this mother of all toy and model trains layout page.

I'm 56 and grew up with the Washington DC and Baltimore MD Christmas layouts of my Dad, Uncles, Grandfathers and older cousins. This little kid was so delighted and permanently influenced - to the good! I custom painted and set up a small LGB layout under the Christmas tree at the church I joined a couple of years ago in the community where I have settled down. You could not believe the joy and response of the folks there. It was fun to watch all the little kids, including the gray haired pastor (: down on hands and knees, enjoying the train. These folks had never experienced an "electric train" before. And they are all awaiting the new one for this year. Thor's web site captures and promotes this wonderful hobby, just like I remember my experience when I was a kid.

Keep this hobby and the joy alive.

Best Regards,

Robert

Arlington VA

rhsbDOThomeATverizonDOTnet

I love the stories about the B&O docksider model on the six inch hat! Thanks Group

Best Regards,

Robert

Don't know GP, but the term has been in use for at least 45 or 50 years. You can bet there is some reasonable explanation, but it's been a very long time. Perhaps the Talgo train was built with bogie-mounted couplers. I never use the term myself, but "everybody" knows what it means.

That's just the way it is. Froggy,

There have3 been published photos of an 0-4-0 going around a silver dollar for the inner rail.

Howard R Garner