LNER P2

[Go_West]

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if ive got this right.

The L N E Railway was in need of a powerful more than fast locomotive to pull the heavy
express trains over the rough terrain from Edinburgh to Aberdeen a trip I took a few years back a line with some good country side and great views of Scotland.
The P2 class was a 2-8-2 steam locomotives designed by Sir Nigel Gresley for this work.
They worked with the Scottish express trains on this highland line and were given famous names from Scottish Myths & Legends

Six locomotives were introduced around 1934 to 1936. They were later rebuilt in 1943
The first locomotive was named Cock o' the North and numbered 2001 this was the first of the batch and came out in 1934 from the Doncaster Works
One of the things that was different about these engines was the rotary cam poppet valve gear and a double chimney with the Kylchap exhaust system each chimney would have 4 blast pipe nozzles.
The boiler barrel was like most Gresley Pacifics design and had a large firebox which needs it to hang outside the frames so taking up as much of the width of the loco as possible.

Number 2001 had also Crosby chime whistle, the name Cock O the North applied to the Duke of Gordon he was so powerful in the North East of Scotland that he was known as the Cock of the North.
Also ‘The Cock O' the North’ is very old tune, first written down over 300 years ago, when it was called ‘Jumping Joan’.
As a pipe tune it is the regimental march of the Gordon Highlanders.

[96RAF]

When I was an apprentice travelling out of Kings Cross on leave I distinctly remember CotN occasionally being on the front of the train. The significance being CotN was a Hotel on the A1 at Durham, where I usually got off the train.

 

If I had time I would always walk to the engine to see what was there, often disappointed if it was one of those awful diesels like DeltIc. Usually it was FS, Mallard, or any of the famous A1/3/4s. I think I remember Blue Peter but surely 1960-63 would have been too early for that name to be on an engine.

 

Would that I could wind the clock back and take a digital camera/video with me, as I do not have a single photo of any of those fine engines and I never took any notes about names or numbers as trains were just transport home for me in those days.

 

Anyhow Ken that is a fine engine for this project.

Rob

[walkingthedog]

Rob Blue Peter was named after a racehorse in 1948 not the TV programme. 

[96RAF]

That explains it then Brian.

Thought the old grey matter was playing tricks again.

Rob

[Go_West]

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So here we go again

With the kit started and the body built to a level that will allow work on the chassis to take place and see what will be the best way to proceed. Being a 2-8-2 wheel arrangement this was going to be a completely new rethink on how the wheels and cylinder can be fitted.

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Long before the alignment of the chimney and steam exhaust can be looked into I took some time to look at the A3 and A4 chassis.First the cylinders on the P2 are much nearer the first set of drivers than on the Flying Scotsman or the Mallard(see drawing here).So much needs to be changed to the Hornby steam chassis to build this 2-8-2 I feel this was not going to be an easy job.

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Looking at the 2 Hornby chassis here The A4 looks to be the better bet for this P2 engine.

I feel its going to be the A3 cylinder assembly as these are more to scale than the larger A4 cylinders but will need a mod to make them fit in the right place.

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What I’m thinking of is that if you look closely at the next picture where the blue ring is drawn around the A4 chassis this is where the first set of drivers will be and there looks to be a square block of metal here which can be used to mount the A3 cylinders on.

All the chassis forward of this block of metal will be cut off and a new fixing point made to fit the body to the chassis. The front and rear axle holes in the chassis are in the wrong place and these will be filled in and new ones redrilled

If you look back at the other picture of the A3 there is no block and if the chassis was to have 15 mm cut off it there would be nothing to fix the cylinders to.

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I have bought some Hornby wheels for the new engine and hope that only the wheel set that drives the valve gear will need a small mod so that the Hornby live steam axle with the small bevel gear can be fitted.

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In the picture here is the A4 Mallard chassis and one of the side frames.

The thing that stands out apart from the longer P2 frames are the difference in the axle positions and the extra axle position for a 2-8-2 steam engine unlike the 4-6-2 of the A4 class.

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The back end of the chassis had it square fixing points removed as I will not be using these to fix the body onto the chassis and in the picture here you can see that in the lower chassis it no longer shows these parts and that the front section of chassis has been removed.

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Now you see the chassis with the axle holes blocked in with some brass rod these holes were first tapped 7/32 x 40 the rod was then threaded and the brass threaded rod glued and screwed in place making a nice solid job so the when the re drilling takes place nothing should move.

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Here you see the frame placed on top of the Hornby chassis and a dummy axle turned up to located the frame in the correct position when inserted in the axle position above it.This will keep every thing in the right place and all that is needed is to clamp it in this position and by drilling through the axle position to the left of the dummy axle and the right we should have the holes in the correct place.

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With the frame from the kit removed you can now see how much out the old holes were compared to the newly drilled holes. These will need to be opened out with a reamer and some bushes made up for the Hornby P2 axles and pressed in place.

[96RAF]

Ken

I suppose you need a piston with a stroke as close to that 15mm as possible and as you point out the A3 cylinders are much shorter than the A4 ones.

 

It may be that you have to go off drawing a tad and set the cylinder position in the chassis based on its stroke and the front driver crank throw arc.

 

Bit of a challenge in places but nothing you won’t be able to overcome given your skills.

Rob

[2e0dtoeric]

Watching with interest.

[Go_West]

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Rob and fellow modellers any ideas?

Thinking ahead these engines started life with this poppet valve system and I was wondering if it might be possible to build this into the model as a working system not to deliver steam to the cylinders o thou this might be a thought but have small shafts that revolve as the engine is moving ? I did a drawing using bevel gears but I would have to make my own gears as I have not found any small enough to fit. The other way would be in the drawing here with a small rubber belt a bit like the fan belt on your car running round the pulleys 

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my idea?

Ken

[2e0dtoeric]

I don't have the engineering skills to comment on the practicality of your idea, but it does seem that you are creating a lot of complication and risk of component failure, for no real purpose other than to say you did it.

Good luck with that, whichever way you decide to go.

[96RAF]

Plenty of scope there Ken as to which sort of poppet valve actuation you want, rotary or cam.

 

For those wondering what a poppet valve is its the same as in your car, but usually the valve is lifted by a rocking cam activated by the drive wheel links rather than the constantly rotating camshafts in your car.

 

These were brought in for steam locos as the standard sliding valve was having trouble keeping up with the need to supply steam at speed. Problems were accuracy of steam delivery and increased maintenance, hence the vertical shafts were tried horizontally.

 

I will do a bit of digging Ken and see if there is a good picture of the CotN gear to copy.  Like here...

 

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[Go_West]

Hi Rob

no doubt you will find something I hope just had a 3rd idea replace the rubber belt for straight cut greas this might be a better bet and will stand the heat and oil

Ericohff

i think your right and this will never get off the ground the valve system from the kit is a brass casting and if all faults then this statistic item will be fitted

Ken

[2e0dtoeric]

straight cut greas - - can you cut greas?  😛 or is it too slippery? 😎

[96RAF]

Some interesting stuff about theproposed new build P2 including discussion around the valvle gear way down the page.

https://www.p2steam.com/design-study/

 

Also this page...

https://www.railengineer.uk/2016/05/20/building-the-p2/

 

And this is good background reading...with great drawings of Lentz gear and other stuff.

https://nearyou.imeche.org/docs/default-source/scottish-rd-centre---past-presentations/151217-p2-locomotive.pdf?sfvrsn=2

 

Rob

 

[Go_West]

Hi Rob

thanks for that info a nice lot to look through will check it out.

ken

yes Eric should be gear so much for preemptive text

[96RAF]

Interesting how many Tornado bits will be used and how the frames are modified to get the cylinders within current loading gauge.

For such a strong tractive loco the cylinders seem awfully short.

Rob

[2e0dtoeric]

Large bore short stroke?

Will the filter stop that as well? 😛

-

No, it didn't!  🤐

[Muzza]

Ken,

Good to see that you always have something on the go.I will really take my hat off to you if you get the rotary gear in motion.

Murray

[Go_West]

Looked through the links Rob posted and it sounds like this is an engine that had some bad problems 

Ken

[96RAF]

Looked through the links Rob posted and it sounds like this is an engine that had some bad problems 

Ken

 

Lets hope none of them transfer across to tour one Ken.

[Go_West]

Rob i think its already too late problems coming thick and fast?

Skipping the working valve gear for the moment as this might never happen just an idea but there is a brass casting of the valve gear in the kit which I can use if the working one never takes off which is pictured here these just need cutting off and filing up and fitting.

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Getting back to the main chassis and the wheels and cylinders there is plenty to sort out here as you will see.First the drilled holes need reaming out Once this is done then some plain bearings are made and pressed in place.

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Now the chassis has to be cut to length and marked out to have a machined step put in it to fix the cylinder to.

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The A4 chassis has as I said before a nice square section of solid metal right in the place that I need to machine this fixing point that I can thread 1.8 mm and screw the cylinder to.

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this was the second time that a section of the chassis was cut off but you can see here just how much shorter its getting

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With the chassis now clamped in the machine vice I started removing the unwanted metal down to the marked lines.You can see in the picture here that I have milled through the brass blanking section that filled in the old Hornby first axle position.

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The cylinder block on this engine needs moving nearer the first set of drivers to be like the model of a P2 wheel arrangement the only thing is if you look at the drawing here you will see 2 square areas that need cutting out to give room for the first 2 drivers the only problem is that the parts that will be removed have 1.2 mm threaded holes to local the valve chest on and there fore a new fixing hole will be needed to keep every thing steam tight.

 

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So again its back to the milling machine and take these parts out of the cylinder assembly.

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If you look at the picture here I have put 2 A3 cylinder blocks side by side and the more brass one of the 2 has the cut outs now in and by looking at the 2 you might see the 4 fixing holes in the left hand cylinder block where as the right hand cylinder block now has only 2 holes left.This also means that the corresponding valve chest assembly will have one set of holes and metal remove to give space for the wheels.

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With the parts machined and fitted in place the front section is taking shape but there is plenty more to sort out like in the picture below you might notice the long valve shaft is too long for this chassis this is because we have moved the cylinders along the chassis to be closer to the front drivers so one end will need about 15 mm chopped off it.

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[96RAF]

I thought you had had a similar problem before with the valvel chest Ken, but after looking back through the previous builds in particular the B12/S69 it was a completely different problem.

Keep at it ...

Rob

[Go_West]

Rob

i think it might of been the 9f but can't remember but these cylinders were on an angle as well 

Ken

[Go_West]

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The thing is which end of the shaft do you cut down? Looking at the picture here you can see the difference between the one on the left compared with the one on the right.

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One end has more work to do to achieve the correct length this is the end in the picture here it has a very small hole drilled in the end of the rod for about 4 mm then an under cut and cross drilled the same small size after which a slot cut in the end this slot then has a small ear silver soldered but only in half of the diameter as in the drawing here.

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Here is the other end of the valve drive shaft which would be just a milling and turning exercise but on checking there was not sufficient material this end for re machining so the more difficult end was tackled.

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First was to cut the valve shaft to the right length 

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Then set it up in the lathe after facing off the end it was centred and drilled 4 mm into the end once this was done the shaft had its under cut put in and the cross drilling.

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Then the small ear was silver soldered in place in the slot at the end of the shaft. All that was needed now was to clean up the end and the ear and remove any unwanted silver solder.

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With the silver solder cleaned up the rotating valve was a nice push fit onto the end of the shaft .

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The finished unit was now place in the valve block and its length checked out .All looked to be in the right place and nice and parallel with the bearing in the bottom of the motor housing. The reverse and forward and valve timing set up was all that was needed to complete this part of the build but before some testing of the engine on compressed air the valve block needs 2 of its missing fixing screws drilled in place.

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The position of these new holes were marked out and drilled in place.The holes were drilled right through the cylinder assembly and into the valve block below these 2 holes were drill 1 mm this would be a good tapping size for the thread that was going to be put in the valve block.

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The cylinder assembly and valve block were separated and the new holes in the valve block were tapped 1.2 mm and the holes in the cylinder block opened out to 1.5 mm and the 2 units screwed together again.The next bit will be to build up the wheels and the connecting rods then it might be time to see if anything is going to run.

 

 

 

[96RAF]

Difficult to say if making a new one from scratch would have been easier and keeping the old one for spares.

Anyhow the cut and shut method seems good Ken.

Proof will be in the testing; good fortune with that.

Rob

[Go_West]

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Hi Rob

this is not a high res picture but if it was you might see more clearly that on the section I have cut off there is a band a darker grey than the rest of the rod. This area is badly worn and is a result of under oiling and poor materials so I had nothing to loose by using this old shaft. I have made these from scratch like I think in the S69 engine but it made sense to use this old shaft as the damaged end would be discarde.

Ken