Return crank position

[Bill DawesParticipant @billdawes]

[Bill DawesParticipant @billdawes]

Hi all, plodding on with my Emma Victoria build, now trying to set up return crank and set eccentric rod centres.

Instructions says rerturn crank set out at x radius and leading main crank.

However on a recent trip on the Dartmouth steam railway I took careful note of the valve gear on loco 'Braveheart', it appears to my inexperienced eye to be Walschaerts type, however return crank was trailing not leading.

Can it be either or is it dependent on some other aspect of design.

Bill D.

[duncan webster 1Participant @duncanwebster1]

Depends on inside or outside admission, and whether die is in top or bottom of expansion link in forward gear (usually in bottom, top very rare). I'll put good money on Henry Woods description being correct for this cause

 

Edit; Brave heart is inside admission, Emma Vic is outside

Edited By duncan webster on 29/06/2023 16:26:48

[Clive Brown 1Participant @clivebrown1]

Advance for slide valves, Retard for piston vavles. Ref; Martin Evans.

[Bill DawesParticipant @billdawes]

Ah yes, piston valve, just googled Braveheart and thtat's what it is., thanks guys.

Now an admission, I have battled for many hours with this valve gear and it's been a case of one step forward one back, several times I have come to the conclusion that my skills are not up to it, just cannot get the whole thing to move correctly, it jams up somewhere whatever I do, I am talking about getting things to operate with engine in staionary setting up position not on the move. I dont't think I have the enthusiasm to remake it all again, I would love to get it finished and working but feeling quite fed up with it at the moment.

A long shot but anyone have a spare set of valve componenents for Emma Victoria they are looking to sell, I guess there are not many people out there that have made Emma. I seem to remember 'Hobby Nut' got off to a flying start (many moons ago) but I thing got distracted onto something else.

Bill D.

[duncan webster 1Participant @duncanwebster1]

If you've made the bits to Henry's drawings it should work. Henry has made two, so the drawings are proven, any errors found along the way were corrected on the drawings (a novel idea I know). Setting the return crank and getting the eccentric rod the right length is the difficult bit. Whereabouts are you?

Edited By duncan webster on 30/06/2023 01:03:48

[Bill DawesParticipant @billdawes]

Thanks Duncan, I don't really have reason to doubt Henry's drawings, I found his series very well written and explained in great detail, when I look at some of the parts I made I think I could have done a better job, sometimes too keen to to get something finished that really requires a lot of patience.

It's another instance where I get frustrated and fed up with it, leaving it alone for a couple of days usually refires my enthusiasm, stepping back and looking at it bit by bit normally finds something silly I have done or not done.

I am pretty well on with it now, frame, axles, bearings, boiler and fittings, smokebox,cab and various steam connections, regulator, superheater so very close to the point where I can start to turn it into a finished loco.

I itemised all the parts above as it makes me feel better reading it!!

Will post again when I progress, in the meantime thanks all for encouragement.

Bill D.

[Bill DawesParticipant @billdawes]

Well perservered and remeasured everything, made a little jig to set the return crank circle, one or two adjustments and looks to be operating valves correctly.

However, a mystery that is leaving me totally flummoxed is that the clearance between the steam chest and valve spindle fork is different on each side, such that on the one side there is not enough room for the spindle gland, must be about 1/4" difference. I have measured distance from buffer beam to valve chest, likewise to motion plate, length of radius rod, lifting link etc and they are all the same each side.. The answer must be staring me in the face, hoping one of you might say "Ah yes, I remember I had that problem once and it was because"…….

Bill D.

[Bill DawesParticipant @billdawes]

Just realised I forgot to update on my dilemma. As I expected the problem was staring me in the face. I stood there one day looking at all the bits and it hit me. When I started making the valve gear (some years ago) i cocked up one of the parts so I thought I didn't want to waste hours making stuff twice which wa a dsitinct possibility as I was still learining as I went along so decided I would make all the parts for one side only to ensure it all fitted.

When I came to make the other side I cut out the second expansion link, I cut it out forgetting the boss that had two tapped holes in to hold it in place, cursing the fact that I would have too make it again I had the brainwave that I would silver solder a piece on which I did quite sucessfully. However due to elapsed time between that and finishing it off I forgot to trim this boss to the correct length, hence the difference between the two sides.

Faith restored.

Bill D.

[Bill DawesParticipant @billdawes]

So annoying. I always read through to make sure of no typos, my dinner is ready is my excuse.

Bill D.

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