71000

No, each side drives both admission and exhaust valves on that side. The middle valves are driven by a cross shaft from one of the outer camshaft drives, but I can't remember which one.

 

Beaten to it

 

I'm not sure whether you're commenting on @LMS2968's first or second sentence. If the first, then yes. Most valve gears, including Walschaerts and Stephenson's, drive slide or piston valves that control both admission and exhaust. But if the second sentence, then no. Most three cylinder locos (at least in Britain) have either three sets of Walschaerts gear or two sets of Walschaerts gear with Gresley derived motion for the middle cylinder.

 

Thanks for that, thankfully Sentinels are a bit simpler.

 

For completeness I should add that three cylinder locomotives on the NER (including the preserved Q7) had three sets of Stephenson valve gear, all inside which made the crank axle very congested with the crank and six eccentrics.

 

Having oiled 63460 up in my earlier years, I’m pretty certain I couldn’t do it now! Mind you, the NER obviously didn’t expect their footplate crews to be anything other than super slim. Anyone who has tried to mount the footplate of a Q6 or J27 on a curve will know it’s so much easier on the outside of the curve and virtually impossible for any one of modest proportions on the inside of the curve.

 

Did the long wheelbase of 18feet and a half prohibit it somewhere on NYMR?

 

No prohibitions on running lines. It may have been prohibited in the now gone beck siding at Pickering station. Several locos were prohibited in there. A long time ago now an I can’t remember. The NYMR didn’t run into Whitby then.

 

Latest Bulletin -Extract:
"On arrival at Crewe there were two areas that required attention. The first was the air pump, which failed during running on the SVR and meant that it was not possible to do any loaded test runs after 24 May. The second was an issue with a bearing on the coupling rods, which was running hot during the transfer from Kidderminster to Crewe. There is also a slight worry about the alignment of the left-hand piston/crosshead, which could be related to the changes made to anchor the slide bar to the new rear cover of the cylinder.

Whilst the Duke is still being a little stubborn and these final adjustments are taking a bit longer than hoped you can rest assured that it is only a short time before we will be able to enjoy seeing the Duke back out on the mainline under its own power.

LSL had hoped to have the Duke ready for mainline testing by the end of this month, but it is now more likely that this will be mid-July, with the first public run from Carlisle to Edinburgh on 13 August."

Given the trouble that the standards with Laird type slide bars had with piston ring wear this extra anchor point , as trialled on the caprotti 5's would appear to make sense, my only concern has been anchoring something to cylinders which get quite hot at one end, and the frames, which dont, at the other....

 

Thousands of engines have used the rear cylinder cover as a front anchor point on the LMS, GWR and Southern; the independently anchored slide bars was an LNER thing which migrated to Southern with Bulleid and partly taken up on the Standards. It wasn't without its own problems, as demonstrated at Settle in 1960.

 

I thought it was a William Stroudley practice, perpetuated by Dugald Drummond. The justification being a) that the support was at the point of maximum bending, and b) that there was no heat transfer from the cylinder.
Happy to edumacated otherwise.
Pat

 

He might have done, I'm no expert on Southern and its predecessors' engines, but many Southern engines used the back cover of the cylinder as the forward mounting for top and bottom slide bars, which was the point being made.

 

Deleted

 

The centre of the slide bar is the logical place to support it when it comes to resisting the forces applied to the bars. There's a big 'but' to this, though, when it comes to alignment. If you only have the one suspension point it is very difficult to align them so that the bars lay parallel to the cylinder. If you are going to align something to the cylinder centreline you really need two points of suspension and the further apart, the better for this purpose. Supporting the bars at the midpoint to cater for force and at the cylinder to ensure good alignment is a good compromise.

 

Interesting but... I'm not being trying to be "clever" btw, but what about all the distortions under running conditions...there are surely multiple forces at play in different axise. As any FEA been done on this ,?

 

Designers seemed unable to decide on this. Stanier's Lizzies had a support at the back but the Coronations had it quite a bit further forward. Both had supports on the back cylinder cover though.

I'm skeptical about the heat transfer and expansion theory. It was the valve chest which took most heat from the steam while the cylinder was warmed as steam entered then cooled as it expanded as the piston moved; this was a major reason for looking at compounding. I also doubt the amount of heat transferred to the slide bars through a small contact area and how far along the bars it would penetrate, and therefore be the cause of expansion.

 

"Plains" I meant axes.... you're quite right... but I would be interested to know, after all, any structure under movement is a big "jelly"..

 

Not in 1954, no!

The major bending force occurs at about the centre of the slide bar due to the offset thrust on to the crank pin. There is no offset at each end of the stroke as the thrust is in a straight line. In forward motion the thrust is on the upper slide bar, the lower(s) in reverse.