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[malcolmbeak]

Oh! unfortunately the photos of the engine seem to have got lost so I'll try again.

[IanJ]

Hi all,


I am so intrigued by the Maudsley reversing gear. Both the Cheddar Gemini and MHB engines look very nice indeed. Trying to get to grips with the mechanism. Can see that the gearing ratio is simply 1:1 and how the timing would work in one direction. I am I right in assuming that it is the length of "throw" of the gear train that sets the eccentric shaft to the reverse position. Trying to get by mind round it, and to understand what is the difference in degrees of the eccentric shaft between that of forward and reverse? Can also see that the valves need to be on the side that would lead to squat engine.




Malcolm, you say you built one; Can I ask to what design, are they any drawings?


Ian

[malcolmbeak]

Hi Ian
The engine is my design, and the "drawings" are more like dimensioned sketches. Back in the 80's Bazil Hartley used to have a column in Model Boats, and on one occasion he showed some photos of a similar engine by a friend of his from New York and gave a short explanation of how it worked. I liked the idea and came up with my own version.
I've just had a look at the sketches and realise that there were several design changes made as I was building. Unfortunately not all have been recorded.
I find I even have a set of castings left!
Malcolm

[southsteyne2]

Hi Malcolm  thanks for the upload love the little engine and I can understand the mechanism after gawking at it for ages bit slow in the old age but still wondering why it was so stiff to move the gear bar as the camshaft and valve gear should not have had much resistance

Cheers
John

[IanJ]

Hi Malcolm,


Thanks for the information. Like John, I am also getting my mind around the mechanism. Given that the majority of components follow conventional design principles, it is the the relationship/gearing between the crankshaft and the eccentric shaft that is of particular interest. Can I ask, are you able to post details/sketches of that particular aspect?


John,


Please post any details of your engine as your build proceeds, as I and I suspect many others would be must interested.


I have no immediate plans to build such an engine as I want to concentrate on the "Marcher" build, but one such engine may be the next project. Although you have got your gears, this company: http://www.hpcgears.com looks like suitable supplier.


Ian

[malcolmbeak]

Hi John


Bear in mind that it is over thirty years since I built this engine. Yes there should have been no stiffness in the mechanism, but having just run it on compressed air I think I know why I used the steam cylinder to operate the fwd/rev lever. When the lever is moved yo either fwd or rev position, the engine starts and the lever starts to move away from the correct running position and needs to be held in place. I assume to do this, the servo would be energised to prevent the movement and I thought that this would run the receiver batteries down. Hence the change to the steam operation.
Hope that makes sense.


Malcolm

[southsteyne2]

Thanks Ian made a start on the engine I don't use drawings just go along bit by bit as log as I have the bore and stroke worked out ,this one will be 5/8th x 3/4 " all done on my little Taig lathe.
The engine will be  powered by a small yarrow boiler also building the tug Joffre  so I am jumping from one project to the next so never boring (no pun intended.
Will keep posting as progress advances
Cheers
John

[Captain fizz]

That is a very interesting lathe John. Unusual to see the ability to move the tail stock laterally.


Simon.

[IanJ]

Hi John,


Thanks for posting. It was just as well you stated that the bore was 5/8' & stroke was 3/4" as the last photo of the cylinder block gives the impression that it's much bigger. Looking forward to further posts as you make progress.


Ian