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

I'll look next time ... but define "section". Do you mean the gross shape of the spring, or a slice through the material making up the spring? Hence in my images above - are you saying they are trying to make something that looks like the top image, or the bottom one?

Tom

 

Love the wobbly bit...always made me smile...

 

I believe it is called Timms section.

 

It's the top one James. Check out the bogie build section of the Hengist/ Clan website.

 

If circumstances permit Tom, please don't forget to grab a few photos. I was also thinking along the lines of the photo you posted.

 

Which is what I thought - hence not understanding @std tank reply saying “no” …

Tom

 

The top image is a square section spring. This can still be made and is used in some safety valves. You will see the difference when you look at one of the bogies mentioned. Oh, I forgot to mention Camelot's bogie.

 

The top one is a square section spring. This can still be made and is used in some safety valves.

 

My hero( mr Webb )had driving wheels cast centrifugal in steel.
These springs will be piece of cake and X ray and ultrasonic control not impossible

 

If Mr Webb had been able to cast satisfactory springs in steel he would have done it. The fact that he did not tells us that it cannot be done because the metallurgy of cast steel is not suitable for springs. I am sure he knew that and we should be guided by his example

Sent from my SM-A105FN using Tapatalk

 

It's Timmis.
GIFY
https://en.wikipedia.org/wiki/Timmis_system
And
https://railcar.co.uk/technology/bogies/springs
The ones I was familiar with on SR coaches looked like a flatish rectangle with a smaller semicircle on the short end. I have no idea what the engineering rationale was.

 

As you can see from the extract from SL/DE/19544, the bogie side check spring is flat rectangular section

 

Very interesting. My gut instinct tells me that this type of spring gives a damping kind of influence that a coil spring would'nt. Correct me if I'm wrong?

 

Wondered if the flat faces give the spring stability if the compression ' bottoms out' ?

 

We have this section of steel in our 40t WELTROL bogies.
2 springs nested and of opposite coiling to each other per wheel set.
One of the smaller inner nested springs was found to be broken and not economical to renew with square section.
So, following advice we replaced it with round section.
Bearing in mind the realistic potential use, speed and amount of movements this wagon is likely to make.

 

We have got an alternative design of a inner/outer round section spring solution. If we went down that route we would need Vampire testing. The bogie side control springs can be fitted at any time so we're not in a hurry to go down that route and will continue searching for now.

Osprey - as you can read in our Construction > Bogie section, E.S. Cox concludes by saying that "only a combination of stronger side control springs plus appropriate damping could give the desired result".

The damping is provided by the Ferobestos pads on the bottom of the bogie bolster cups. These sit on top of grease lubricated brass pads. The original 1951 BR Instruction Manual shows that these pads were grease lubricated

 

Not really. It still behaves exactly like a conventional round wire coil springs in its basic behaviour. Mostly, it's a way of getting a shorter spring (both free and fully compressed) for a given set of characteristics.

All coil springs are basically torsion bars wrapped into a helix, so the wire is twisted rather than bent like the leaves of a leaf spring. Round wire is fundamentally the most efficient solid shape for coil springs - you get the highest proportion of the material at your limiting stress and the maximum stiffness for a given material cross section (so you can have less of it). But if you've got a design operating in a fixed envelope, that just needs to be that bit stronger, or that bit stiffer, or that bit shorter, the most efficient spring may not be the best choice. You can make the windings square or rectangular and stiffen them without changing the turn-to-turn pitch, or you can close up the pitch but maintain the same gap between turns.

 

That sounds ominously like the sort of trade name used for products containing asbestos. Could anyone please clarify?

 

and yet

Vampire testing would take account of numerous variables and parameters. If everything apart from the spring will be exactly the same as on the original, and the inner and outer springs together would have the same characteristics as the original square-section spring, it's hard to see how the behaviour could be different. Whether the behaviour of the original design was ideal in all respects is different question.

 

No, at least not any more. It's a fibre reinforced resin, used as a frictionless, hard-wearing surface. It's still used quite a bit in the rail industry. The cab front corridor connections on modern units have it, so when they're coupled together the corridors slide rather than bind. Bottom of sliding doors is another location.