We're a UK based organisation building a full size Class 6 "Clan" Pacific locomotive with the intention of mail line running. You can read about it here https://www.theclanproject.org/.

In order to meet railway certification rules, we need to keep as close to the original drawings as possible. We are very lucky as most drawings are available for copy at the National Railway Museum in York, UK. The front 2 axle bogie has rectangular section coil springs for lateral control which are proving very difficult to source. These have a 6 inch outer diameter and most similar die springs, available commercially, go up to a maximum outer diameter of around 2.5 inch.

We know that lateral control of the bogie is very important. E.S.Cox, the designer of the Clans, had had some very relevant experience in India in 1938 when investigating riding issues with the Indian XB Pacific. His autobiography tells us that this experience was adopted in his designs.

We have approached a number of spring suppliers in the United States, UK and Germany without success. We we wondering if anyone in your community had had experience of this type of spring and knew of a supplier?

Thanks

Ian

This may be a case of where replacement with nested round wire springs with similar performance characteristics is "as close as possible". I would be shocked if springs with that radical of a rectangular wire section could be sourced today.

That being said, you might try Suhm Spring Works. They have made rectangular wire springs for us in the past.

Kelly

Thanks for the response. We have had a proposal from a UK supplier for nested round coil spring solution which were are looking at. The spring rate is not quite right and that is being looked at. We will probably have to convince the certification authorities if we go down this route; other locomotive groups have a similar problem.

I've attached an image of the solution with the springs fully compressed. We calculate that the end stops are reached before the spring is fully compressed. I understand that its not a good idea for the latter to happen

Ian

You might also consider stacked Belleville washers as a possibility.

We've had a discussion on stacked Belleville washers already on a UK forum. The certification bodies have said no. I would be worried about grot and grime - inherent to steam loco operation - getting into the washers. One comment on the forum said

I'm not sure we could get away with that on the UK main line!

Ian