Joy valve gear Jeannie Deans

Hi, further to my recent post about the valve gear for my Jeannie Deans I have another problem. The valve travel just isn't sufficient. The total valve travel is 5/16 inch. The ports are 1/8 and the lap is 3/32 so the valve travel needs to be 7/32 x 2 i.e. 7/16. With the current valve travel the ports will only open 1/16. What is your opinion please? Would I be right to reduce the lap to get more port opening? It is not possible to get more valve travel, the angle of the slide is about 48 degrees from reverse to forward, the books say don't go above 50 degrees. I solved the other problem, just cut away the connecting rod back end so it can be slid over the crankpin with the bush removed.

I have no pretentions as a designer of valve gear, but it is not unusual to find ports do not open fully in published designs.

Whether 1/16" will be sufficient or not demands someone with far more expertise than me, I am afraid.

Perhaps looking at one of the computer valve gear simulators might help, as might enquiring on the MECH website which tends to be far more loco orientated.

One sorce of help might be Martin Evans book, locomotive valve gears. Noel.

I'd second Nick's recommendation that the Model Engineering Clearing House ( Proboards) would perhaps be a little more loco orientated.

I do remember getting flummoxed that my first loco's valve gear did not open the ports fully ( Rob Roy) untill it was explained by a fellow club member that they did not open fully. Like nick I'm not sure if 1/16 is enough opening, but I'm sure someone on the MECH will be able to help.

Dave

If you're only getting 1/16 opening with 3/32 lap the max cut off will be quite short. If you pm me your email address I'll send you some more info, radial valve gears are a bit of an obsession with me

Thanks for replies everyone. I think some of these old designs should come with a health warning! I had similar trouble when I built a Lion but I eventually got it running. I think one of the problems with the Jeannie Deans was that LBSC never built one and like most of his designs they were knocked out in a hurry. Our little locos will run with even poor valve events but it would be nice to get it as good as possible.

I always understood that LBSC did build a Jeannie Dean and unlike most of his engines was quite detailed. I understood that after his death it was passed to a long time friend of his, Reg Hanks, it was then stolen and has never been seen again.

The above is from memory, i am happy to be corrected.

Hi, according to Brian Hollingworth's book he did build one and it was stolen from Reggie Hanks house in Oxford, Curly made modifications to overcome problems from which the prototype suffered, but no construction serial was published, but drawings were made available.

Regards Nick.

As a follow up to my previous post i had a quick look in my archive and found a photo of LBSC’s Jeannie in an 1958 ME No.2971. Also in ME 3312 he shows a drawing for an intercepting valve operation lever that his did not show on his original drawings also he discusses the link motion which i assume is used on the middle low pressure cylinder.

Hi, I'm happy to be corrected, so he did build one. Daggers please could you send me copies of those articles if you have them? I don't have them, I haven't any LBSC articles about this loco.