6023

Irrespective of the above,... we still need bodies to help.

 

Tom isn't wrong........

 

Similar in the car world. I was involved with TVR cars in the 80's. Autocar tested a new model and it was down on performance, compared to factory specs. When I questioned the MD, he said that they never measured it but looked at other cars with the same engine and and just guessed on better figures as their car was lighter

 

Sorry I won't be around this weekend.

 

I seem to recall that the official weight diagram for the Great Bear showed its centre of gravity in a substantially different position to the measured axle weights (the Chief Engineer took a great deal of interest in the Bear's axle loading so it was probably measured more than most locos)

 

Regarding the weight distribution, I have made a weight calculation for the 6023 with design values from a german textbook.
Result: 89 tons which the locomotive actually weighs. Then of course the centre of gravity was easy, it is where it should be,
halfway between the first and second driver. I ventured next into Clapeyrons "three moments" calculation which, even with a pc, is a nightmare. Again, nothing wrong with the reaction forces, the first driver needs, theoretically, some spring adjustment
to take more load and lighten that on the truck. Conclusion: it is useless to speculate about the weight distribution and the like, something else is the matter and the crew needs time to scratch possible causes from their list!
Kind regards
Jos Koopmans

 

i have a wee bit of inside knowledge, and the GWRS need to get a grip on things and sort out the King's springs and weighing ASAP.

my personal view is that the new rear springs are far too stiff. Jos and myself plus many others await patiently the results of Jos's redraughting which was very badly reported in the December Railway Magazine - as what 6023 now has is nothing to do with experiments carried out by Sam Ell in 1952, but uses the most modern up to date principles.

cheers,
julian

 

Spring setting can be most frustrating. At very least if you change a spring on one side then you have to change the one opposite it. Even two nominally identical springs can be different and we've had to test load and match them up before getting a result. Daft things like brakes and spring pins binding can effect the results even from test to test. So even all the best will in the world it's easy to understand that it will take them a while to get the correct set up.

 

Why?

 

Its a bit like if you change a car tyre the flexibility and diameter of the tyres between the new one and the old is different thus afecting the weight distinution and so the handling. in the case of a spring the old spring will be weaker and deflect more than a new one thus giving an uneven diflection across the engine. We just had a case of replacing a new front left spring and the right hand rear failed due to the wieght moving diagonally. If we had put two new ones on the front at least it would have been cross balanced.

 

Interesting theory although I don't accept its validity.. Does anyone else subscribe to it? I accept that every spring can be slightly different in camber, stiffness and hysteresis, which is why you really need to weigh and set up accordingly but not changing opposite springs. That's a waste of time and money.

 

It is valid, If you don't want to believe it then that's your prerogative.

 

I asked why you did it and you explained. That's fine with me.

 

This is not an option which is really open for debate. The instruction to also change the opposite side was pretty widespread on the real railway. In service springs, particularly trailing springs on 4-6-0's settle very quickly and can be subject to loss of camber and weakening. Section 4.05 of MT 276 spells out the requirements quite well and is a bit of a weakening on the stance of changing both springs of the wheelset. However the requirements for ensuring that the other spring is compatible are quite clearly set out in this section. Given a derailment of an engine which has had a single spring changed, you may well be in line for an embarrassing discussion with the HMRI.

We generally find that very few observers actually understand just how little service life was to be had from springs in railway days and if anyone is interested, there is an interesting tabulation of spring user in E S Cox's "Chronicles of Steam" book. Try working out how many Black 5 and Scot springs they got through in a year.

 

Funnily enough I was reading that this morning... The numbers are quite amazing. The average life of a bogie spring on a Stanier pacific was a tad over 6 months, and those on the couupled wheels lasted less than 9...

 

As you say, MT276 does require you to be satisfied that the replacement spring has been re-tensioned to the original settings, (which I don't think you can practically do) otherwise the loco needs re-weighing, which is the sensible approach. It doesn't require you to change the other spring.
As someone who has come off the road with a passenger train due to an incorrectly fitted spring, I am naturally concerned about springs being correct.

 

Here is today's protect using a new digital scales. In this instant we found issues with spring pin heights. Like I explained a soft old spring having 5mm more deflection than a new one. These effected the ride high and the travel in the horns all indirectly to the spring settings.

 

Sorry to be a duffer again, but can someone explain what camber means in a locomotive spring please?

I understand what it means with respect to motor vehicle suspensions.

Dave

 

hi dave,

camber is the curve of the spring if leaf springs.

Bob has very kindly provided the 'correct' view.

both 6024's rear springs have been replaced.

re Nigel Day you cannot adjust springing correctly if on one side the springs are softer than the other side on the same axle. they both need the same load 'rating', and this rating should match what that axle requires, otherwise deflection differs.

it is not unusual for new leaf springs to be made to spec and have to be returned to the makers these days.

cheers,
julian

 

Starting curvature (or lack thereof) of the unloaded spring leaves. Basically the vertical distance between the ends and the centre of the longest leaf. Loss of camber means that dimension is reduced or starts increasing the wrong way, due to plastic deformation of the leaves.