How Big On 22"

Hi from the UK.

Due to a house move I now have a smaller but better model room.

My old layout had 30" radius curves. My new layout needs to have 22" radius curves to get decent operation.

The only problem with is is my Bachmann 4-8-2 Light Mountain binds on the corners, the front truck contacts the inside of the cylinders. Although Bachmann recommend 22" radius for this loco.

I would like to get bigger engines like 2-8-2, 4-8-4 and 2-10-2. Again Bachmann say 22" radius is ok for these locos. Am I having fails hopes or is the problem just with the 4-8-2 Light Mountain?

Tiddles

Tiddles,

Even though a locomotive may be given a minimum radius rating of R??“, it doesn’t necessarily mean that it will operate without some issue. 2-8-2 Mikes generally shouldn’t be a problem on R22” curves. Larger locomotives - like Mountains and Northerns - are going to be pushed to the limit on tighter curves.

I have a BLI 4-8-2 Mohawk and 4-8-4 Blueline Niagara. They’ll negotiate an R22" curve…but you can hear the drivers grinding slightly through the curve. I also have two 4-6-4 Hudsons (w/ 79" drivers) that don’t care for one particular section of my layout where there are opposing curves - even though the curves are separated by 9" sections of straight track. All are rated for R22" curves but…they don’t necessarily like them.

Tiddles, if you are having to downsize because of space restrictions, it’s probably best to accept the fact you’ll need to “momentarily” retire a few of your larger locomotives - for the time being, that is. (Or, only operate them on a larger layouts.) The bright side is that this gives you the opportunity to discover and enjoy the wonderful world of switchers and switching. [Y]

Tom

It may just be with your loco. I have a Bachmann 4-8-4 Niagara that takes curves as tight as 18". Same with a Mehano CN 2-10-2. Some manufacturers will state that their locos can take a "X"r curve but that’s an absolute minimum. It doesn’t mean that it will do so reliably and in some cases can be used as a selling point to modelers who have a layout with tight curves.

My 4-8-2 Heavy by Bachmann does R18’s day in and out without issue.

The light version should be able to do the same without doubt as the wheelbase mechanism is the same.

I have a 2-10-0 and most of the smaller engines and they all run fine on 18" radius code 70 and in fact I use the 2-10-0 as a test engine and run it everything from dead slow to unprototypically fast, no problems but your track-work has to be very well done.

I am surprised at the amount of comments saying the loco will go around 18 radius curves.

Peco 3rd radius is 19" and 4-8-2 Mountains will not go around them with out the leading wheels completely locking up against the cylinders.

Although there is no problem with the drives.

My Bachmann light mountain goes around my 18" curves with no problem. It’s about 10 years old so can’t say about the newer ones.

Gale