2" Clayton Wagon valvegear

[jcsteam]

Hello all,

I recently acquired a part built clayton wagon. It seems to have been built to a good standard thus far although it has yet to have the boiler and engine built and assembled. There are some parts of both ready to go though. 

I have been doing some digging as to modifications to make it more user friendly and it will be fitted with an additional shaft between the engine and the rear axle. As well as the steering shaft and nut modified. However I know the engine suffers from poor valve gear, so I have been comparing Don Youngs 4F with the Claytons joy valve gear. It appears that the issues with poor valve gear start at the connecting rod. The length of the Clayton con rod is 5.0625", the 4F is 5.065". However the hole in the centre of the con rod, is 2.625" on the Clayton and 2.69 on the 4F so to start with the circular motion of the claytons drive for the radial gear is already reduced. I have compared quite a lot of the measurements and found differences all over. 

Has anyone drawn a modified valvegear for the Clayton wagon yet and if so where would I find it?

Regards
Jon 

[nonort]

Please don't compere the two sets of valve gear both have there problems. If you put the dimensions into a simulator think the Docstader one you will see the problems in real time. After much twiddling of numbers I got mine to work very well. It would pull thirty stone on flat tarmac. Take the blast pipe out to the largest diameter that you can and it will stop the engines propensity to eat grates. The safety valves as drawn will not clear the steam make the seats one size larger and the vent pipe of quarter dia pipe. I fitted a small LBSC donkey pump into the area under the passenger seat in the cab. The feed water heater boiled the water as drawn so I reduced the coil to half it's length. The steering thread I made as a two start thread Now a days I would probably search for a three start thread as used on 3D printers etc available from Ebay. I didn't fit a cab roof as it would have gotten in the way, and there is documented evidence that not all of the wagons had rooves anyway. The lay shaft arrangement is a definite good thing to do. As built the wagon had a top speed of over twenty miles an hour! All the best and good luck.

[jcsteam]

The trouble is I don't actually know how to use the docstader simulations. So working out the differences between the 4F and the Clayton, I acn try to squeeze the 4F joy gear into the claytons dimensions without effecting the outside appearance. I know that the 4F is far better than the Clayton so that's at least a step in the right direction for me.

Jon

[weary]

Jon,

Apologies if you know this already ...... but here goes .......

Bernard Lundberg wrote a number if articles for Model Engineer magazine (ME) covering modifications to this model. His objective was to make the whole model more accurate to prototype. Amongst the articles he covered valve-gear. He designed and built his own in the image of the original vehicles albeit with some variation. I don't know how detailed or useful the articles may be.

If you put Lundberg as a search term into this index you should find the relevant ME issues.

Jasonb of this parish may be able to give you some links to relevant postings on other fora.

Regards,
Phil

[Jo]

I have (part) built a Clayton.

From memory: Bernard designed a much nicer front axle which I made for my engine.

The Clayton is supposed to be very fast hence the intermediate shaft to slow the model down. I did this by adding an additional shaft and gears within the crankcase.

I seem to recall I got frustrated with trying to get the joy valve to not jam and that is where it sits today.

The so called water heater acts as a condenser rather than heating the water.

Jo

[brucevoelkerding]

I remember Don Young mentioned something about the Derby 4F & 2P valve gear, but was not sure what it was. I had subscribed to his magazine LLAS for a year or two. This morning I came across LLAS magazine #26, dated Feb 86, mixed in with my ME back issues. In this issue Don was describing the building of the 2P. Here are some extracts -

"Just one point to be mentioned for those who have purchased drawings ahead of Sheet No. 3 appearing in LLAS, in that the slideshaft has been moved from the center line of the slides to the top of them. I put the slideshaft on the center line originally because this was the approximate position full size on all engines fitted with Joy valve gear, plus this helped mask the presence of said Joy valve gear in lieu of the authentic Stephenson gear with rockers, but it meant in practice that the .16 inch dimension of metal to be removed between the slides had to be exceded to achieve working clearance for the vibrating links, and although the end result was perfectly satisfactory, moving the slideshaft upwards to what I would call the "LBSC position" means the drawing dimension can be adhered to, thus saving me a query or two."

Note in the text above "slideshaft" refers only to the .38 x .38 x 2.75 bar which is a component of the "slideshaft assembly". The fulcrum pin location was not altered.

In the same issue referring to the Slide Valve -

"Incidentally, when my 4F pencil drawing was traced back in 1974, a poor 6 became a 0, so what should have read .561 inch became .501 inch, something that was perpetuated initially on the 2P. It was in fact a 2P builder who advised me of my error, I guess that by the number of 4F's already running at the time it was a rather obvious mistake, so I simply corrected the drawings and forgot about it. Unknown to me, however, the designer of the Clayton Steam Waggon that has become very popular through a series in "Model Engineer", used those 4F cylinders and repeated my dimensional error."

I don't remember if the Clayton Waggon was 2" scale. I hope I didn't make any transcription errors,
Bruce

[jcsteam]

Well after a not massively entertaining few hours working out dimensions for the Clayton wagons valve gear, I am now going to recheck all my workings out. I have downloaded the dockstader program and after a false start, using the wrong simulator. I'm now somewhat on the right track by using the joy1, outside admission simulator. Inputting the dimensions is a hassle, but I seem to keep hitting an error as soon as I try to put in the straight slides, it simply doesn't allow it. I'll check back with you all shortly. However if my information is correct it is no wonder Jo has found the gear to jam. My simulation seems to create an error message at certain points in the valve gears travel.

I'll check back here shortly once I've verified the measurements I've put into the simulator.

[mbrown]

I am not sure if this is going to be helpful or not..... but you may be interested in the actual valve gear that the prototype Clayton waggons had which was nothing like Joy gear.

It was a shifting eccentric gear where a longitudinal movement of the shaft carrying the eccentrics moved their relative position through wedges.

The drawings below are from Ronald Clarke's "The Development of the English Steam Waggon".

In my view, it would be a hugely challenging, but highly interesting, project to try to build a 2" Clayton with the wedge valve gear.....

Just a thought!

Malcolm


20230108_111830 by malcolm brown, on Flickr


20230108_111732 by malcolm brown, on Flickr

[jcsteam]

I think I've cracked it.

Firstly thanks to Phil, (no need to appolagies), I have got a collection of ME mags next to my computer. Containing articles on the Clayton, including all of Bernard's ME articles,as well as the reduction drive.

Malcolm thanks for the drawings in the wagon book, I have seen those drawings once a long time ago but haven't seen them again. Bernard does write an article on improvements to the engine, however these are mainly cosmetic, but the joy valve system is replaced with eccentrics driven from gears as in the photos you show above.

Right Claytons joy valve gear. I did indeed make a mistake to begin with and forgot to subtract 3/8" which is on the trunnion guides, and goes into the front of the engine case so that explained why it didn't look quite right.

The simulator wouldn't work with straight links, being a radial valve gear having a straight line in the valvegear caused an issue. Initially I used the 4F's slides radius of 3.5". This helped eliminate the error from the program, so that I could look at the other elements and how they effect the valve gear. None of the cylinder holes or dimensions have been changed, the crank to cylinder centres remain the same, and the connecting rods remain the same, so only smaller items within the crankcase should need to be remade to achieve the valve timing with equal lap of 0.094, and equalise, lead of 12 and 13 thou, for the rear and front steam ports respectively.

The changes that have been made are as follows,

•the radius of the slide link is 1.5" instead of straight
•The radius rod length is increased to 2.222"

Edit: I should have said that the cut off is 71.3% front, 76.3% rear when in reverse. Reverse arm 2.100, centre is 5.4% front, 6.4% rear, reverser arm 2.427, and 83.5% front, 85.2% rear when in forward gear. Reverser arm 2.827.

If anyone is interested the full figures for the docstader sim are as follows, I have reduced the reverser arm to cent norm and max to 0.400" from shown so that the valve remains within the steam chest lol.
20230228_234239 by Jon Cameron, on Flickr

20230228_234306 by Jon Cameron, on Flickr

[steamer5]

Hi JC & Malcolm,
There was a series in the ME on building the valve gear along the lines of the drawings that Malcom posted. I had a link to a site that had the Clayton build series, the link is now broken! I can’t remember if the updated valve gear was in it . A search on the link by Phil above should find it.


Cheers Kerrin

[jcsteam]

I've spent a number of days now working in the dockstader simulator, trying to improve the joy valve gear on the Clayton.

Are there any helpful hints that anyone could provide on laying out joy valve gear that may prove helpful?

So far I've found that with the straight slides the simulator simply won't process the data, and I get error messages all over. I therefore changed the slides to a radius equal to the radius rod that connects to the valve rod. Also after checking my dimensions a couple times to the drawings the crank rod needed increasing by 1/8" so that the piston would travel the full length of the cylinder. This can be achieved by changing the rear bearing to a slightly larger one and offsetting the bearing hole, therefore increasing the length of the connecting rod. I believe this error has crept into the drawing as the rear cylinder cover width (1/8" has not been included when the valve gear was schemed out by Dyer.

These dimensions I've checked twice against the drawings, and I'm surprised that any clayton wagon is running. I'd be interested to hear from builders of the Clayton if they found this error or worked around it somehow?

By changing the above dimensions, resulted in the valve having a cut off in forward gear of 54.6% front port and 99% rear port, and in reverse the front steam port not having any access to steam inlet and the rear 97%. Also that the valve would overshoot the valve chest wall by a small margin. Therefore I have reduced the valve stem centre to centre length to 3.825" instead of the 3.975" as shown on the drawings.

This has shown a great improvement in the simulations I've run, even allowing for expansion of the steam which the joy gear is supposed to be so great for. Comparison with the above changes are as follows;

Forward gear;

Front steam port 82% cut off

Rear steam port 87% cut off

Reverse gear

Front steam port 89.1% cut off

Rear steam port 90.5% cut off

Notched up a little to midway between full forward and centre position

Forward gear

Front steam port 48.7%

Rear steam port 59.9%

Reverse Gear

Front steam port 52%

Rear steam port 73%

Still a long way to go but vast improvements.

Any help and input would be appreciated.

Jon

[jcsteam]

Ps I've now done some cleaning up of the Clayton and got the chassis into black paint, which will help keep the rust gremlins at bay and working towards cleaning up what else is there to get it in paint.

20230226_085342 by Jon Cameron, on Flickr

20230226_091749 by Jon Cameron, on Flickr

20230226_082834 by Jon Cameron, on Flickr

20230303_182738 by Jon Cameron, on Flickr

20230303_182757 by Jon Cameron, on Flickr

Jon

[Jo]

This all looks familiar to me

Jo

[jma1009]

As a bit of an aside, the Don Young v Dyer tiff I recall investigating some time ago. Don’s thing about a wrong dimension of the slide valve perpetuated by Dyer wasn’t quite correct based on the ME drawings of Don’s loco - his last - for ME.

I remember discussing this episode with Don Ashton.

It might have been due to something cropping up on here. Or the official ME forum.

[jcsteam]

I did come across a thread on this forum from around 2014, but decided not resurrect it. That discussed the Clayton and 4F valvegears, Don was surprised to see his name mentioned more that that of the designer Joy.

I have nearly got the redesign sorted, I just need to tweet it so that I have some cutoff at centre position. Not that it's vastly important, but it would for me be nice to get it almost equal the full range of positions. There is now steam expansion within the cylinders which the original design didn't allow for. And looking at a nice graph produced by the simulator it matches the shape of the one that's pre programed into the simulator. The joy gear in the Clayton is rather cramped which probably accounts for poor running overall. I have tried to stay true to what don would have done and not change everything. However, there's only really the cylinder components, trunnion, anchor link, and engine case that's not changed, the slides, and other linkages are all slightly modified.

I be grateful if when I'm finished with my tweeking of the numbers if you could look at the simulation in dockstader with my provided numbers and tell me if you think it looks about right. I'm still fumbling my way around the dockstader sim.