minimum radious

[ianmac]

Here is one for the experts

How do you workout what the minimum radious for a loco is

Is there a formula where you can enter wheel distance and track gauge and then are given the minimum radi

Cheers
ian

[PH]

The advice I have heard is 20 times the rigid wheelbase for 5 inch. I haven't checked it with other 'experts' so it may be wrong

[alanstepney]

The "20 times" is a reasonable rule of thumb.

You can calculate it, but it isnt worth the effort.

[chris vine]

Interestingly (well to me anyway) an 8 coupled engine may go round marginally tighter curves than a 6 coupled. the middle bit of the curve in the middle of the wheelbase is in the air on an 8 and so does not affect it so much.

That's is what i was told by someone who owns a full size 8F.

Chris.

[simonwass]

I draw the loco out in CAD and move the wheelsets over to full side play, L & T fully left, D fully right. I then draw an arc to touch the treads and get the program to tell me the distance to the theoretical centre point of the circle.
The 7 1/4 Paget will just do a 40ft with narrow centre flanges, I imagine it squeeling like a pig though.
The comment on a 4 axle machine doing a tighter curve would be correct, but usually 4 axles are longer than 3 so effect would be eliminated. I'll have to draw some prototypes out to see though.
I was going to say a 5 axle loco would not follow this rule but as they have flangeless drivers the curve in the air bit would be larger, I wonder if there is a risk of the wheel dropping off the rail on a very tight bend?

[mutley]

It was quite comon for a flangless driver to drop of o tight curve in the shed or yard. Correct procedure was to call for asssitance, most drvers kept going and it would sort itself out and save the grilling from the shed master. theres a picture in a book somewhere Ill find it.

Andy

[ianmac]

Mabey i sould explain what i have done

track width is 45mm i have made my distance between the flanges 41mm so that it can get around the track easily and this conforms the the lgb standard by the looks of it..

So if the loco is 15cm or 150mm from front axel to rear axel then by that calculation i would need a 3mtr radious is that right?

Sounds fairly large for gauge 1

[Tel]

I"m using 1500mm radius on mine - a bit tight, but so is my space

[ianmac]

I think my tightest radious is 2m and thh widest with the most gradient is 3mtrs and 1 in 60

i will have to wait and see how it goes and adjust the layout to suite

[Tel]

You should be ok with that