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Post by donashton on Oct 2, 2014 16:40:07 GMT
There are some very odd things about the Q1 valve gear. It is very rare to find the wrong use of link (unlike in the model world!). Whoever made this choice knew very clearly that it transgressed the norm. The rocker increases the valve travel a great deal, or working in reverse the eccentrics can be smaller. This is odd because the required launch link would have meant much smaller eccentrics by default.
The angularity errors tend to cancel, which is the reason for the suspension being considerably ahead of the slot in an attempt to equalise events. With a normal locomotive link arrangement the residue of error at the axle almost cancels out, and the majority of such gears ignore the fraction and suspend centrally.
So here we have a designer deliberately mixing himself a bottle and one wonders who and why. I don't think that Maunsell was a valve gear man - perhaps Holcroft was responsible. The 'C' gear would only do for a piston valve with outside admission - some more rather odd thinking.
Don.
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Post by sncf141r on Oct 2, 2014 18:58:01 GMT
Regarding Nick Feast's design - has anyone (is anyone) here building one?
I do have plans, boiler materials-inna-box, and have CADded up some items for water jetting, and CNCing (like, wheels). All I need is to retire so I have the time!
I really enjoyed Nick's writeup, and have enjoyed our brief email exchanges.
(finishing up some current projects, but the Q1, or maybe 2 Q1s are in the Q)
JohnS.
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Post by Deleted on Oct 2, 2014 19:01:15 GMT
Quote}---All I need is to retire so I have the time!...............HAH !!---- Don't you believe it
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Oct 2, 2014 22:20:37 GMT
hi don, re the Q1 valve gear i think you have to go back to the SECR E1 redesign using the existing E valve gear of loco links reset, with new piston valve cylinders. the same were then copied on the SR L1 (Maid of Kent!), and were copied again on the Maunsell Q class. as no E1 or L1 survives, ive asked ben to check whether the Maunsell Q has outside or inside admission piston valves, the Bullieid Q1 having outside admission piston valves as did also the MN and WC etc pacifics. the Q class was built using standard parts of the L1. Holcroft describes in some detail the rebuilding of the E and L classes to E1 and L1 with the alterations to the valve gear, and was no doubt fully aware if not had a hand in designing same. cheers, julian
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Post by donashton on Oct 3, 2014 7:13:14 GMT
Thanks Julian - your Holcroft library is better than mine, but I'm sure that he is the 'culprit'. This use of the 'wrong' link brings us to the thread about Martin Evans' misuse for the slide valve Manor. You appear to have come across an SV of excellent build quality, which could mask the distribution problem. Of course, we are not talking about measurements and tests here. Despite being surprised at complaints, Martin did his best to discover what caused the problem. I had every sympathy - the learning curve was very steep!
Don.
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Post by donashton on Oct 3, 2014 9:56:04 GMT
Hi Ben,
The rebuilt outside gear is one of the finest sets of Walschaerts' gear that I have come across. The inside is a poor match, as if designed by a different engineer. I altered a few things, including a union link 1.25" longer, and Braunton's engineer was quite keen to do this modification, but the minor tweaks elsewhere would have entailed new parts at some expense.
Don.
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dscott
Elder Statesman
Posts: 2,438
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Post by dscott on Oct 3, 2014 12:26:38 GMT
Hi Ben, What we do when resting from workshop construction!!! Well I took a few photos inside the engine shed at Sheffield Park during our visit in the Summer model show and totally enjoyed the day. Katie chose a Schools in OO gauge so we are modelling the Southern. Great excuse to buy a Q1 which sits upon some of the best model track from C & L. She sits next to the N weathered to perfection ready to pull some Green coaches that have seen better days!!! All I do is timber at the moment so a layout is no trouble... We also got a 5036 in Black of course and Katie likes them as she was invited onto the footplate at Cheltenham oh that's the Schools!!!
I am currently asking round the club to see if anyone has a set of Minx drawings as a C3 in several years time would be quite an unusual and neat Locomotive to build once all the scale parts have been worked out. Hiding the design within the Maid of Kent and having Reeves and others not update them and advertise separately is I think the reason they are so rare!!! I drove one at the North London track when I lived near (Enfield) and she was wonderful, in fact two boys had her running all day with father just looking on.
David Scott Also with too many Locos in a Q!!!!
And here I am thinking of building them full time???
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Post by donashton on Oct 3, 2014 15:22:30 GMT
"David Scott Also with too many Locos in a Q!!!!"
Well David - it's a disease, believed to be incurable, though I suspect that nobody has tried.
Don.
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Post by Deleted on Oct 3, 2014 16:17:39 GMT
Why would I want to ??-----------It's my la raison d'être --- and then mix in chocolate and cream --- -voilà !!
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Oct 3, 2014 23:42:35 GMT
hi ben,
the late jim ewin's groundbreaking 5"g 0-6-2T loco (made into an LBSCR radial tank) was based on the LBSC MINX joy valve gear design. ive driven this loco, plus the C2X MINX in the Beechurst club (cant remember the owner after so many years) but both were excellent 5"g locos.
cheers, julian
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Post by Deleted on Oct 3, 2014 23:51:52 GMT
Hello Julian---late tonight aren't we ??-----------I've been wondering if my 5"g GWR 633 valve gear is the Minx one ??...That'd be a turn-up for the books, eh ?? Has anyone some photos showing this Minx and it's Joy valve gear ??-----------I'm in the process of YET AGAIN re-arranging my Swindon "A" shop so I'll take some photos and post on here ---- but won't take up any more thread space afterwards...Promise !!
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Post by donashton on Oct 4, 2014 7:02:45 GMT
Jim Ewins' engine was a delight to drive.
The other hard working Minx would be John Seymour's.
Don.
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dscott
Elder Statesman
Posts: 2,438
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Post by dscott on Oct 4, 2014 11:57:09 GMT
I have been rained off working on the two remaining walls of the new workshop so I am posting my 517 Th post. Could start another trend on a little celebration when one of the loco numbers you are working on co insides with your total to date of posts! Yesterday saw a modern celebration for internet couples!!! It was exactly 10 years ago That mice clicked and we met on the dear Web. Well I was on a site called Dating China which found my dream girl for the second time!!! Yes meal times improved tremendously and yesterday saw her mixing concrete after helping shift about two tons of soil in the way of the new workbench. I found a lovely supply of windows of the double glassed variety from the window companies, they often have miss measures which when the old window comes out the new one is slightly the wrong size and ideal in the main working area!
Hear is to our next 10 years. David.
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Post by simon48 on Oct 4, 2014 15:48:07 GMT
David - "And steaming into my life comes a part built Speedy now I can go to a LBSC rally when she is finished!" Join the club. (not a Speedy though). I wonder if the father and son team finished their Speedy in the Ply-mouth-full Society, back in the 80s?
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Oct 5, 2014 9:08:22 GMT
going back to the valve gear discussion of the Q1s and their use of outside admission piston valves with loco links and indirect drive, i managed to dig out my GA copy of the SECR E1 rebuilds and they do indeed have inside admission piston valves as you would expect with loco links and 180 degree rocker arms. cheers, julian
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Post by donashton on Oct 5, 2014 15:24:42 GMT
Well, bit of a brainteaser here.
If SECR E1 had loco links and indirect drive, like the Q1, then it must also have had outside admission valves, PV or slide. Otherwise it would have to do all its forward running with the linkage strung up in 'back gear'. Ugh! It is still the 'wrong' link, as the Q1 offset suspension shows, because all the angularity errors are on one side of the equation instead of opposing each other.
That is why the Dean Singles and 4-4-0s drove directly, but later PV conversions dictated outside admission valves to avoid changing the gear.
Don.
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jma1009
Elder Statesman
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Post by jma1009 on Oct 5, 2014 17:01:12 GMT
hi don,
ive never analysed same as havent built this arrangement but i was under the impression that loco links with indirect drive and inside admission piston valves would be better than outside admission piston valves with the same arrangement of loco links and indirect drive?
one of my locos has launch links with indirect drive with slide valves worked out to your excellent book and performs superbly! (my 3.5"g FR loco LINDA)
if (as i assume) the inside admission arrangement is preferrable to outside admission piston valves on the indirect drive loco links, then i can imagine O V S Bullied walking into the drawing office and saying in 1938 'I want outside admission piston valves on the Q1' and Holcroft and the drawing office staff saying to themselves, (under their breaths) 'so be it'! i am waiting for Ben to confirm that the Maunsell Q is inside admission - which would indicate that a new pattern of cylinder was required for the Q1 which is a bit odd.
cheers, julian
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Post by donashton on Oct 5, 2014 17:57:27 GMT
Hi Julian,
You can't have a link arrangement but please yourself whether it is used for either inside or outside admission - the choice of one decides the other. If Bullied (thanks for your correct spelling!)wanted outside admission he would know what that entailed in the gear provision.
Your loco with launch links with indirect drive to slide valves is right, with the least trunnion offset to account for angularity errors. The Q1 trunnion offset is massive as it struggles to compensate. as I said,it also tell me that the designer knew full well the consequences of ignoring the almost universal (in full size) choice of the correct link. The unknowing Martin Evans thought that you can please yourself until I pointed out the error and he studied the drawing method in my book.
Cheers, Don.
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Oct 5, 2014 19:18:03 GMT
hi ben, that is very very interesting, and will know doubt cause don and myself a bit of head scratching as to why this occurred. i cannot think of any logical reason why it should, and launch links should have been fitted. cheers, julian
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Post by donashton on Oct 5, 2014 21:48:48 GMT
Thanks Ben,
The plot thickens!
Don.
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