BR Standard class 6 No. 72010 'Hengist' and Clan Discussion Thread

No, not yet. We continue to make enquiries about this. The good news is that lack of the springs does not hold up progress with the bogie as they can be fitted at any time.

 

I suppose it would be theoretically possible to mill the required trapezoidal section from rod but the problem would be in finding a machine that could accommodate the length of bar required. Has that avenue been investigated?

 

I found this company you could ask to see if they could roll the Timms spring section for you.

https://www.realwroughtiron.com/wrought-iron-products-and-services/rolling-mill-hire/

 

We don't think that producing the trapezoidal section would be much of a problem. The stumbling block seems to be forming of the coil. A company in Rochdale used to have the formers for rectangular section coil springs but disposed of them some time ago. One spring company we discussed it with were concerned about the time that the bar would be out of the furnace while the coil was formed, i.e. the bar would cool down before the coil was finished

 

It is good to see the continuing progress in both small and large parts, everything is coming together slowly and carefully.
I hope there is an Open Day soon so folk can see the actual progress.

 

Yes, this Saturday! Please see

https://www.theclanproject.org/

 

Can the completed spring be machined from solid and why not?

 

I don't think so..springs aren't made like that..all sorts of reasons ..grain flow..column stiffness...et al...

 

We did approach a company in Worcestershire about machining the springs from solid. The price was very high. We were worried about machining marks being stress raisers and asked them how they would tackle that. Nothing heard

 

I've jumped in here with both feet. I have not followed this project in detail so the spring subject intrigued me and now see where we are coming from. I didn't realise this design featured this type of spring on the front bogie. I'm not surprised you're having difficulty scourcing these here, have you tried the USA? Just a thought...

 

Oh yes! We approached a number of companies in the USA including one that proudly proclaimed that they could manufacture any spring. We sent them the details and they responded by saying - they couldn't.

 

Well I'm afraid I've been out of engineering now for some years having "retired" so I'm a bit out of touch. Forgive me if I'm teaching you to suck eggs, as it were, have you tried India? There are some quite good engineers out there..finding the right one though..all I can say is keep trying. I suppose using an alternative method will need reapproval?

 

We did try firms in India without success - there is probably someone out there who can do it but its a matter of finding them. We do have an alternative design of inner/outer round section coil springs but that will need Vampire testing. The last time we checked, the cost was around £20,000. Here's what the P2 Group had to do https://www.p2steam.com/design-study/ - scroll down to "Vampire".

If you have a look at

https://www.theclanproject.org/build/Clan_BuildTopic.php?topic=BWA&description=Front Bogie

you can see the alternative design

If anyone wants to help us find a supplier for these springs, we'd be very grateful. We can provide drawings and spring data.

 

Have you assessed the round section side control springs as fitted to the Royal Scot class 46100 to 46170. The drawing No. is D53-21821. It is in the NRM drawings archive. Also, at least one Stanier Class 5 currently being overhauled has been fitted with double spring round section bogie side control springs. Contact NYMR loco department about this.

 

Wheelsets and suspension are considered to be critical items and our Assessment Body is looking closely at this area. So any changes to the design (which for all BR standard 4 wheel bogies used a rectangular section springs) would require Vampire testing. Does the NYMR Class operate on the main line?

 

As rectangular section springs are clearly no longer available, you have no option other than to use a design of round section springs. May I recommend that the two pairs of short springs are done away with and just two long springs are designed and put through Vampire testing. I have already given you one example of a BR modification from rectangular to round section springs in the Royal Scot class. Perhaps you could assess that for starters.

 

Anyone know why rectangular section springs were used, apart from maybe making best use of space? As a non-engineer I'm guessing that a circular coiled spring would have a uniform curvature throughout its length and that the load placed upon it would be spread evenly along the length of the spring material. A rectangular spring would suffer greater stress at the corners where the curvature is tighter, thus more likely to fail. Just a hunch, I'm happy to be told I'm talking nonsense.

 

I did some work with Royal Spring Company in Bengal a few years ago for truck springs. I think they also did railway springs but no idea if the do trapezoidal. Usually in India if you talk of a low production volume they lose interest. Then when you talk quality standards and you see head wobbling you know you are in trouble. I have not been following suspension parts for a while now so the world may well have moved on. I won't mention Russia....

 

OK, I might be missing something here - but I assumed what was being discussed was a coil spring, but in which the cross-section of the bar that forms it is square (or rather, a trapezoid that ends up square when coiled up). I didn't think they meant a square that was literally square, i.e. with 90 degree corners?

In other words, they are trying to make this:



Not this:



Have I got that right?

Tom

 

No Tom. Have a look at the side control springs on the bogie of one of the Standard 4 2-6-4 tanks you have at the Bluebell. The springs are rectangular section.