Removing the screws in Slaters wheels

[simond]

All you ever wanted to know about wagons but were afraid to ask….

Railway Clearing House wagons

www.cs.rhul.ac.uk

image 1020 shows the axle.

the kids are home for Christmas, one graduated last year, and t’other is on course to graduate next year, both Master’s in Engineering. I too am similarly qualified, and between the three of us, we can’t see a reason for the specific shape - we wonder if it’s to do with the manufacturing process. There is negligible shear force along the central portion of the axle, and the bending moment is constant. The tapered shape is obviously lighter than a cylinder of the major diameter, but heavier than one of the minor diameter, which must be sufficient, so we’re at a loss to offer an explanation.

MrsD is not an engineer, and may therefore deserve your sympathy.

 

[Jordan]

between the three of us, we can’t see a reason for the specific shape - we wonder if it’s to do with the manufacturing process. There is negligible shear force along the central portion of the axle, and the bending moment is constant. The tapered shape is obviously lighter than a cylinder of the major diameter, but heavier than one of the minor diameter, which must be sufficient, so we’re at a loss to offer an explanation.

Coincidentally, over on the 'US Model Dabblings' thread we have also been discussing axles - Post in thread 'US model dabblings' 7mm - US model dabblings
... to this day American freight car axles tend to be tapered. We haven't got around to discussing "why?". We just got a bit engrossed in the matter of improving the appearance of a particular R-T-R manufacturer's axles appearance.

 

[Eastsidepilot]

I found this document Determination of critical section of wagon axle by considering dynamic and safety factors
I'm not an engineer ( I'm a chippy ) but is it to do with a need for the axle to flex under load so that it does not shear and to do that the dia. is reduced to allow it to do so.
Col.

 

[simond]

Thanks Col,

I’ll not pretend to have followed the maths in any detail, but the diagrams do suggest a fundamentally constant bending moment and negligible shear between the wheels as I expected. The axles under consideration are not tapered, they comprise a series of cylindrical sections, with transition radii between, and the highest stress area is shown to be that between the drive gear and the adjacent wheel, which seems a reasonable place to expect it, and of course not relevant on a 9’ wheelbase wooden bodied minerals wagon

if you want to spread out the flexure and prevent a stress raiser, then having the whole axle at the minimum diameter would do that, having a zone of smaller/smallest diameter must have some tendency to concentrate stress in that zone.

in conclusion, I still don’t know why they did it!

 

[Osgood]

Wagon axles were I guess all forged, as the wheel seat area needed to be of larger diameter than the central section, and bearing journals could be smaller, and forging produced a much stronger axle than one machined from straight bar.
The tapered central section does also produce a modest but important unsprung weight saving.

Modern axles with varying diameters are forged by passing through a CNC set of 3 skewed tapered rollers - I wonder how wagon axles of the 18/1900s were forged? That may explain the shallow taper.

Many freight stock axles are now parallel and the trend (especially for driven axles) is toward hollow axles where the parallel outer diameter is determined by the wheel seat and the inner diameter varies instead of the outer.

 

[Marc Dobson]

one supects that the first rule of mechancal engineering was applied. "Hit it with a big hammer and if that doesn't work get a bigger one"

Marc

 

[Brian McKenzie]

Modern axles with varying diameters are forged by passing through a CNC set of 3 skewed tapered rollers

Skew rolling is a process offering less longitudinal stress on the machinery as it can automatically be driven by the axial component of friction. Maybe it is for ease of manufacture that is resulting in the slight taper?

In model form, I suspect it is how S7 modellers make their axles longer. . . .

 

[Dog Star]

- I wonder how wagon axles of the 18/1900s were forged? That may explain the shallow taper.

Tony, (@Osgood ),

Be my guest, here.

and then follow "Patent Axle company" down any adjacent rabbit hole (or visit the Black Country Museum).

regards, Graham

 

[simond]

Excellent rabbithole, thank you Graham

Patent Shaft and Axletree Co - Graces Guide

www.gracesguide.co.uk

Cammell, Laird and Co - Graces Guide

www.gracesguide.co.uk

I'm a Birkenhead lad ( the “one-eyed city”) who did some of my training at the shipyard, so that link was unexpected & enjoyable

Merry Christmas
Simon

 

[Osgood]

Thanks - I'd tried down various holes for Kirkstall Forge and Chas Roberts but had forgotten all about Patent Axle Tree (even though I knew about their own siding and locomotive ).

And there was also Wortley Top Forge that I'd forgotten all about, and just look at those wooden wheel centres - what was all that about then?

https://flic.kr/p/2kRKfoy

Happy Xmas all.

 

[Richard Gawler]

I don't want to be a killjoy and be seen to be taking this back on-topic
but this is newly-purchased Slater's wheel screw - it looks a bit like a Torx socket to the naked eye but really it is an Allen socket with some swarf inside.

 

[oldravendale]

So is this another peasant trap, Richard, in that the swarf will need removing before an Allen key will work?

Brian

 

[Osgood]

Is this the explanation?
The broached hole is hex, but the bottom radius of the turned recess into which the broach goes has been just nibbled by the broach - which makes it appear as if the sides are Torx-shaped, when in fact it is only the top lips of the sides that have become scallop-shaped.

 

[Crimson Rambler]

I was led to believe axles were turned tapered with the smallest diameter in the centre to introduce a deliberate point of 'weakest' and was located as far as possible from the changes in section involved with the wheel seats, bearings etc. In effect any axle bending i.e. flexing in service would be encouraged to take place at the centre of the axle and thus remote from the diameter changes which would otherwise tend to generate/encourage (premature) fatigue cracks and failures.

Be that as it may, the following is taken from Railway Carriage & Wagon Handbook - no date but appears to be from the late thirties:-


Crimson Rambler

 

[Lancastrian]

My interpretation of the situation, Simon. I'm helping someone with a coarse scale garden railway he's trying to resurrect from dereliction after his father's death some five years ago. Sadly his father had Alzheimers for several years beforehand so the railway has not seen any use for probably ten years or more. Actually the owner of the railway has limited interest in it but his son does so the work we're doing is really for him. As an electronics engineer he has, however, built a new analogue control panel.

Doubtless the chap could have got hold of someone competent but I'm bodging for him until he finds that paragon.

For the above reasons we don't actually know that the wheels have been Loctited in place. So far driving wheels have come loose on two of the locos but on the Hall one wheel is loose but I simply cannot undo the other one and have already made the Slaters key in to spaghetti (very al dente). The owner of the railway said, in a throwaway moment that it had probably been Loctited in. Perhaps, in his declining years, that's what his father was prone to do. Who knows? The loco is beautifully and probably scratch built and has Slaters FS wheels but it runs quite sweetly (when it runs!) on the coarse scale track.

That's the background. I met the owner only this year so have very limited history. He had already reinstated two of the tracks outside (using Peco) and we're hoping to reinstate the remaining two in 2023. After all, I have absolutely nothing else to do.

Here are a few photos taken on my phone during one of the hottest days of the year. Fortunately his mother makes wonderful ginger cake and endless cups of tea so I was well sustained.....

Brian

Oops - apologies for the diversion to a thread about removing wheels.....

View attachment 176589View attachment 176590View attachment 176591View attachment 176592View attachment 176593

View attachment 176594View attachment 176595View attachment 176596View attachment 176597

Brian,

Looks like John Chamney's garden railway !

Ian

 

[Lancastrian]

Back to Allen screws and keys, I purchased a number of these....

Bondhus 15949 1.27mm Hex Key - 72mm Long | UKtools

UKtools Professional Hand Tools, Specialist Socketry from Koken Tools, Facom, Britool, Gearwrench, Signet, Trident, Elora, Knipex, Bondhus and more

www.uktools.com

The problem I found with the Slaters Allen key was they deformed which then caused the screw to be damaged. Being of a higher grade material, the replacement is a better fit and certainly more robust for undoing tight or stubborn retaining screws.

Ian

 

[oldravendale]

Brian,

Looks like John Chamney's garden railway !

Ian

Right on the button, Ian. I live just up the road in relative terms and had not been aware of it until now. Doubtless you know more of the history than I do but it's good to be involved, even if only on the periphery, with the resurrection.

Brian

 

[Clarence3815]

Horses mouth.

I have a friend who used to be works manager at Ashford Railway works - home to the wheel shop.

I asked him the question this morning and his reply was...

`The principle reason is to do with stresses along the length of the axle plus the need for the diameter of the wheel seat to be large enough to provide a reliable press fit seating for the wheels. In my day a 50 ton back pressure test was applied between the wheels to ensure they did not move!`

 

[Lancastrian]

Lovely project though Brian, sweeping curves and long trains! Very nice control panel as well.
All the best
Julian

Julian,

We ran a 98 vehicle freight train there one year.

Ian

 

[markjj]

View attachment 176745
I don't want to be a killjoy and be seen to be taking this back on-topic
but this is newly-purchased Slater's wheel screw - it looks a bit like a Torx socket to the naked eye but really it is an Allen socket with some swarf inside.

That looks very much like Slaters are not clearing the swarf out no wonder the allen keys will not fit in properly.