4472 wheelsets

Talking twaddle????????? No ,simply trying to explain to a bunch of people who can see no good in any thing Southall that we did take precautions to prevent damage being done . There is a vast difference in sitting 22 tons on something designed to take it as opposed to using 3' of leverage with 3+ tons hanging on it trying to pull it out of shape...........perhaps a mathmatical genius on here would like to work out the forces involved !

 

The yorkshire post articale seems to read like the 6100 saga also....

 

To get 3ft of leverage you'd have to have a single lifting strop almost at one extreme end of the axle, but even then the load just be badly out of balance, you'd still have the other wheel providing some counterbalancing. A locomotive driving axle is probably around 9" in diameter (I'm guessing, but even a carriage axle is around 6" in diameter) and I suspect that would take more than 3 tons to bend it!

 

Odd that isn't it.

 

It doesn't take a mathematical genius to work it out! It's elementary trigonometry. If you lift the wheelsets using a very short sling and putting it around the rim (not the axle) then you can put a very large lateral load onto the wheel itself, certainly enough to deflect it. i'm not saying that anybody (NRM/Southall/whoever) did this, though!

 

That is why many railway works had beams to lift wheels with, we use one of these at Didcot to avoid problems. There are times when you can't use them, such as when tipping wheels on end to fit tyres, nut at that point you are not pulling the wheels together.

 

At long last..somebody with a reasoned unbiased engineering based reply Thanks Steve.

 

Well I'm not an engineer, and I've forgotten all the trigonometry that I was never any good at, and I like to think Im not biased - I can't see how incorrect lifting of the wheelset could damage it, therefore I conclude that the problem lies with the tyre not being correctly fitted in the first place and then not being spotted as out of spec. I can't see how it is possible to generate enough leverage, even with the whole weight of the wheelset and the leverage of the whole length of the axle, to exert sufficient force to move a wheel pressed on with say 50 tons of force. And why does the length of the sling around the wheel rim matter? I'd be interested to see the maths even if I won't necessarily follow it!

 

As you said, you're not an engineer make no claim to understanding trigonometry, so you've given your own explanation. As an engineer who does understand trigonometry, I can assure you that a short sling would impose severe latteral forces on the wheel rim, which could well be enough to distort it. As to the tyre being incorrectly fitted, it would be turned to size AFTER fitting, and any run out would be apparent at that point.

I offer no suggestions as to the distortion of this particular tyre, but offering engineering opinions immediately after stating ignorance seems an odd thing to do.

 

YOU ARE RIGHT MR LMS2968 WHAT YOU SAID IN LIFTING WHEELS, GOES TO SAY AT WORK WHEN WE LIFTING MONOBLOC WHEEL SETS WE HAVE TO HAVE A SPECIAL LIFTING FRAME FOR THEM. FISH 7373 SOUTHALL 81C FITTER

 

Imagine it like this. You want to lift a wheel set, and you are going to do this using slings through the wheel rims. I f you have a pair of slings hanging from a beam which is the same length as the the wheels are apart, then the slings will be vertical, the weight will act vertically and there will be no forces trying to pull the wheels together at the top.

Now remove the spreader beam and hook both slings directly on to a central lifting hook. The weight of the wheel set is now NOT acting vertically, and depending on the length of the slings, more or less of the weight is acting horizontally, trying to pull the tops of the wheels together. The longer the slings, the less the force, as if they were infinitely long then they would be near to vertical.

The larger the wheel diameter, the worse the effect as the wheel radius is acting as lever, multiplying the forces at the hub against the axle. So for very small wheels, not such a problem, Scotsman, much bigger problem.

If you imagine the guy on the rings at the Olympics - you can see the force he has to exert to hold the rings apart with his arms out horizontal, as opposed to when he just hangs there with the ropes vertical.

Of course none of this explains Scotsman's problem if it can be fixed by a tyre change!

Iain

 

That's a perfectly good explanation for a sling lifting on two wheels, but I interpreted the previous "short sling" answer as being for a single point lift by one wheel or the other. As always with these things, it's quite important to establish that you are talking about the same thing before flying off the handle!

 

I wasn't flying off any handles. I am an engineer, and that is what I interpret "short sling" to mean. Pardon me for wasting my time.

 

I wasn't talking about you, thank you for taking the trouble to offer an explanation.