Loco Minimum Radius

Hi,

Does anyone know where I can find the minimum radius curve a steam loco can travel round?

I have managed to find the radius for the Standard classes, but I would like to know about things like Bulleid 4-6-2s, SR 4-6-0s/4-4-0s, GWR 0-6-2Ts and 2-8-0Ts, LMS 2-8-0s/4-6-0s, LNER & LMS 4-6-2s plus any smaller tank locos that may have longer wheelbases; E4, N2, N7 etc.

Thanks

Matt

 

For the GWR ones I think it is on some of the outline drawings in books, try the "locos of the royal road" or other similar books that have these. If I remember correctly the information is there for some but not all classes. The drawings are like these, GW Drawings but they have more information bellow such as grate area etc.

 

From the GWR diagrams Baldric refers to the 5600 figures are 5 chains normal and 4.5 chains slow. For the 4200 class the figures are 6 chains normal and 5 chains slow.

By way of contrast the 1361s specifically built for confined areas could negotiate curves with a radius as small as 2 chains!

 

whatever it is you haven't got space to model it in 00 scale!

 

Guys,

Thanks for all the information. It is really useful and believe me, this is no 00 scale layout we are plotting here. We are redesigning our yard for the future and want to ensure we can fit almost anything into it!

Does the 4200 class require the biggest radius curve or is there anything else out there we should take into account?

Matt

 

Can't answer for the other regions/companies but for the GW locos there are drawings showing the additional clearance at key points on the loco required on curved track (several radii figs quoted). Clearly these figs are also important if you are running on curved track with adjacent structures etc. These drawings are/were held in the BR(W) Civil Engineering Offices.
From memory GW 2 cyl 4-6-0s generally need 7 chains or 5 chains dead slow - probably the most demanding would be a 72xx but I have no figures for these.

 

The 72xx can go round the same curves as a 42xx.

If there are buildings or platforms you need to worry about the overhang on coarches etc, particualrly GWR saloons or very long vehicles such as the 70ft railmotor and autocoaches.

 

We have had a curve radius issue at Newbridge on the NYMR recently.
Hopefully now sorted by uplifting the track demolishing about 10m of the loco pit and realigning the track to give approx 6.5 ch radius.
However some further comments have come to life in that whilst a loco can traverse minimum rad curves it can be a different matter if they are likely to be stored there for any length of time.
That will also need to be considered.

 

No mention of gauge widening in all the above. Are the figures quoted without any widening or is widening automatically added on sharp curves?

 

Only possible if using timber sleepers.

However as stated in the PWI Handbook 4th ed 1971
10 - 7 chain radius = 1/4"
7 - 5 1/2 ch = 1/2"
under 5 1/2ch = 3/4"

These figures would not normally be added on unless authorised by the Civil Engineer.

 

The King requires a minimum of 8 chains.

 

Going to be at least that for a 47xx ? or a P2 !

 

The 47xx may not as it has a lot of movement in the rear axle, if I get a chance I will see if I can find out later.

 

For ex LMS locos there is a section with drawing details for min radius and other dimensions at Barrowmore Model Railway Group (BMRG)

 

All the inside framed GWR 4-6-0s were shown in the diagrams as 8 chains normal 7 chains slow as were the 4700s , though if I recall correctly the 4700s were more restricted as to the routes they were allowed on, presumably due to clearance of the outside cylinders with the longer wheelbase.

 

Those are the engine diagrams. The purpose of which was to communicate the basic data of the locomotives between departments. Particularly between the mechanical engineers and the civil engineers, as well as management. One of these would be produced even before detail design work was commenced. In fact there are many engine diagrams in existence which were never built. They were also the scene on which the battles took place over route availability. Some of the data can be taken with a pinch of salt. Especially axle loadings. I know of several examples of the axle weight of the actual loco exceeding the ED handsomely - by several tons in some cases. The minimum radius is usually okay, though occasionally a little optimistic.

 

Guys,
Thanks for all the advice. Most useful.
Matt