1st Radius Curves

[kebang]

My original design for this layout uses 2nd. radius curve. Usually I use a mix as my rolling stock (4 wheel coaches, short wheelbase wagons and 0-6-0 locos manage these comfortably. However my daughter arrives her next month with a brand new bachmann 2-4-2 L&YR Tank, (Happy Birthday Dad!) and a used bachmann Ivatt 2-6-2 Tank.

My new plan is to mix alternatively Ist and 2nd rad.,(red track is 1st rad.), this would give me the ability reach the top left corner to remove a planned scenic hill, tunnel for track cleaning etc. Does anyone have any idea if these new locos would cope with this? Or should I go back to all 2nd. Rad and abandon the tunnel idea?

[Dad-1]

Hi kebang,

I don't have either of the Bachmann Locos mentioned, but they would probably struggle
on 1st radius.
Can't you await arrival of the said models before actually fixing the track work ? Then
after a suitable test decide ? Usually building a layout is not time specific, so why fret,
just be patient (I know not always easy).

Geoff T.

[Mountain]

Is normally only an issue with more modern larger locos, but there can be the odd smaller one that struggles (Practically all 0-4-0's and most 0-6-0's will do it).
Bachmann locos are not really built to negotiate first radius curves though. Sometimes one can adapt a loco to do it by filing things so they have more play, and also with six or more coupled wheels, one can remove wheel flanges from centre wheels, but it is butchering ones lovely locos a bit to do that.
Strangely at times it can be the couplings which don't like it. Larger wider couplings solves this. The older versions of the Bachmann class 03's with such a short wheelbase run fine on first radius with the exception of when one tries to double or triple head them, where the couplings fowl each other.... But after removing one coupling hook so only one is present between the couplings they ran well.
But go back to 00 gauge models built before the mid 1990's and it is rare to fine a loco or item of stock that doesn't run on first radius curves as the manufacturers went out of their way to design them so that they could due to so many modellers layouts using them for space saving purposes.

[Bufferstop]

A large coupler on the loco with it's hook removed usually works even with narrow couplers on the stock. Watch out for Hornby's hooks they are longer and when coupled with shorter hooks ride up on the back of the coupler. They foul on the pips where the hook is pivoted.

[Bigmet]

You are unlikely to have trouble. The simple fact is that the standard set track point actually goes below R2 in parts, because the curved road is a compound of straight, curve, straight, curve, and thus for the curved road to be able to substitute for a second radius curve piece, the curved sections must be smaller than 2nd radius. So the manufacturers have to provide a smaller than R2 capability, and although that doesn't stretch all the way to R1, it's not that far off.

Sometimes a very small modification is required for 1st radius. Common examples are to slightly chamfer the inside edge of the brake shoe mouldings for a little more coupled wheel side play, and to enlarge the swing of pony or bogie wheels by cutting away anything fouling, such as the inside of a step. These can usually be accomplished with no damage to exterior appearance.

As the 2-6-2T has outside valve gear, before running make a careful check by looking at the model from the underside, sighting through the side rods, and moving the coupled wheels from side to side to check whether the rods could foul. Any past mishandling which has bent a rod inwards should be corrected.

I can tell you that the Bachmann WD 2-8-0 will run around R1, that needed only a little paring away inside just 2 brakeshoes to make it run freely on the curve.

[GeraldH]

I have quite a few first radius curves on the BNR and quite a collection of locos, all of which run through them. My Bachmann Ivatt 2-6-2 with a split chassis works fine. The important thing is to avoid reverse curves and if you do, quite a few locos that specify minimum second radius will go around first radius. I do also check before buying any new locos and I don't buy the latest super detail ones. There are various lists online showing locos that will negotiate first radius. I have a list somewhere that I have compiled from various forums over the years and can post it when I find it.

[kebang]

Many thanks to all who replied. I really must learn patience! I really wanted to get the track sorted before my daughter arrives with my birthday present so she could see it working properly. So I will lightly pin down a 2nd radius oval and run the new loco in on that. Then I will try the combination oval and see if the new locos can manage it. These really will be the largest locos I will run as its still a small layout really only suited to tank locos.
If they struggle I will have to rethink my scenic hill and tunnel.
Really grateful to you all for your wise counsel!

[GeraldH]

This archived thread from another forum entitled " Best Locomotives for Tight Curves " might be useful...

https://www.rmweb.co.uk/topic/10851-bes ... t-curves//

[Mountain]

The real railways had a similar issue where some lines certain stock could not be used for one reason or the other. For example, on the Heart Of Wales line which us traincrew would refer to as "The Central" (Central Wales line) we could not use class 158's at all as the doors could not open on Llandybie and one of the other platforms as the doors touched the floor of two of the platforms up there, and we (Carmarthen or Swansea train crew) were allowed to take classes 142 and 143 up there, but we would have to take all passengers off with their luggage for them to transfer to the train which we met coming up the other way as the Crewe traincrew had not signed those units as a safeguard against using those trains because they could not negotiate the tight curves at the Shrewsbury end of the line. Have been known to get 143's stuck where the drivers had to wiggle them back and fore to get round "The curve" out of Swansea on occasions!
In model form, I tended to try to fit check rails to first radius curves (And some times second radius) for a realistic visual effect as on the real railways all the sharper curves had them to help keep the trains on the track. To do this in model form, one really needs to have a lower profile rail for the checkrail as the railchairs get in the way.

[kebang]

Thanks for the link GeraldH, interesting anecdote Mountain!

[Dad-1]

We also have our own list on NRM, often backed up with short videos.

https://www.newrailwaymodellers.co.uk/F ... 34&t=51816

I can only test locomotives in my personal collection and that's not growing now
as I already have more than I can justify.

Geoff T.

[kebang]

That's a really useful list Geoff! For the moment I've kept my test oval mix of 1st & 2nd deg curves intact. Had a delivery from Hattons this morning of , amongst other things, a pack of 4 Genesis Coaches and 3 Dapol wagons. I wanted to see if the coaches (particularly the 6 wheeled versions, would be would be ok.

The coaches were fine, but the 2 axled wagons were derailing all the time! This surprised me as I have 6 x 4 wheeled coaches (old hornby) that have no problem. (Purchased from End to End, one of the few survivors from the Great Typhoon of 2021). Are Dapol wagons prone to falling off the tracks?

Once my new locos arrive I'll add them to your list of those that will and those that won't!

[Bigmet]

... Are Dapol wagons prone to falling off the tracks?...

Dapol have some form for this, turned out a 6 wheel milk tanker some years ago with 3 hole disc wheels that had a completely wrong profile. The tyre was cylindrical and the flange was perpendicular to the tyre, with no transition. The edge of the flange was sharp, and there was coning on the inside of the flange. These wagons would work themselves off the rails even on straight track.

If those wheels are still hanging around and get fitted, they are useless...

[kebang]

I noticed that the wheels on these had 3 holes....

[Bigmet]

I noticed that the wheels on these had 3 holes....

The holes aren't the problem! Now, compare the wheel profile to those on vehicles which stay on the track...