maid of kent valve gear

[wiremanParticipant @wireman]

can anyone suggest which type of valve gear is best when building a 5in gauge Maid of Kent, i understand the original

stevensons was not a great success? i know Joy Valve Gear can be used however would anyone recommend Don Youngs stevensons modification ?

Many Thanks

Wireman

[duncan webster 1Participant @duncanwebster1]

There are several valve gear modelling programs which will answer this issue. You could also get a copy of Don Ashton book, or read my article in ME.

[Chris KaminskiParticipant @chriskaminski64716]

Is your series of articles likely to be available as separate item in print?

I used to be able to get ME from my library, but it is no longer available (despite my pleas …)

I have enjoyed the first few while I still had access

as for Don Ashton’s revered book, I have a copy but it is hard work 🙂

much preferred your approach.

[duncan webster 1Participant @duncanwebster1]

My master plan is to have a website with it all on, but the round tuits are delayed in the post.

Check your PMs later on (sat waiting at opticians currently)

[Chris KaminskiParticipant @chriskaminski64716]

Will do,

thanks

[Nigel Graham 2Participant @nigelgraham2]

K.N. Harris designed it with an improved version of LBSC’s original, mechanical rather weak, Stephenson’s Link Motion.

LBSC had also designed Joy valve-gear for it, and looking at the drawings that seems better-designed at least mechanically, though I can’t judge its operation.

[Charles LamontParticipant @charleslamont71117]

It is not so much a question of a choice between valve gears. Well designed Stephenson’s will work as well as anything else, but don’t tell that to a Churchward fan.

[duncan webster 1Participant @duncanwebster1]

There seems to be 2 versions of MoK, one with inside and one outside cylinders. Which one are we talking about?

[SillyOldDufferModerator @sillyoldduffer]

My experience of this subject comes via Duncan Webster, who has read the books etc,

From my armchair, I believe:

• In terms of producing accurate events, Stephenson’s gear is near perfect.  The disadvantage, and it’s serious, is that the gear has to be mounted between the wheels under the engine, making maintenance difficult and expensive to repair when it goes wrong. Full-size.
• Walschaerts is nearly as accurate as a Stephenson’s, with the important advantage of being easier and cheaper to maintain because it can be mounted on the outside of the loco.  The motion is a little complicated and liable to wear and tear.
• All the others are compromises, with advantages that might be attractive, or not:
  • Avoiding a patent
  • Fewer moving parts
  • More robust / improved reliability
  • Simple adjustment on the road
  • Can be fixed in a limited workshop

Which alternative best suits a model loco is beyond me.  Whilst fitting a Stephenson’s to a full-size loco is a problem if a 50 ton engine has to be lifted off it with a big crane, the same gear in a small model may not be a bother at all if the owner can rotate the engine on a stand or flip it over manually.  Depends how heavy it is.

The complexity of a Walschaerts may not be justified on a model loco where a simpler or more robust motion will do the job just as well:  full-size have to squeeze maximum mileage from every ton of coal, but it doesn’t matter if a model is a bit inefficient.  A straightforward reliable valve gear feels more attractive.   Joy…

Dave

[SillyOldDuffer]

On SillyOldDuffer Said:

Whilst fitting a Stephenson’s to a full-size loco is a problem if a 50 ton engine has to be lifted off it with a big crane …

It doesn’t. You can dismantle the valve gear from underneath.

 

[Paul KempParticipant @paulkemp46892]

It can also be fitted outside the frames – Black 5.  There is also a fundamental difference between the 2 gears that could be an advantage to a model, constant and variable lead.

Paul.

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