A few questions about Joy, valve gear that is (of the NER variety)

[Rob Pulham]

I am not sure whether this thread should ultimately be in techniques or not?

I picked up a set of Joy valve gear for the F8 from Laurie Griffin at Telford.

This is what I got in the set.



In Laurie's instructions there is a diagram that shows the creation of a cylinder back plate with it's dimensions but there is no mention of setting up of the cranks. Thanks to Steph and Richard's accounts on inside valve gear, the actual fitting of them is quite clear but my guess at this point is that you use the distances on the cylinder back plate for setting both the slide bars and the cranks on the axle?

What is only mentioned in passing in Laurie's instructions is making a motion plate. It also suggests that you use a rod between the frames to attach the anchor link but there are two curved castings supplied to create bracket off the motion plate and I guess what is meant by that is shown in Richards Joy valve gear parts photos (linked from RMweb - I hope that you don't mind me linking them like this to illustrate my questions Richard?)

My question for the more knowledgeable is do I need to make a motion plate like the one below? And does anyone know if NER joy valve gear used the brackets off the motion plate to retain the anchor links or rods across the frames? I have a GA for the F8 on order from the NRM but my best guess is that it will be the end of September at the earliest before it arrives





Another assumption is that I cut off the curved ends of the slide bars to leave them looking like those in the photo of Richard's above (working on the theory that they have curved ends to assist with the casting process and to save them getting damaged before they get to the customer).

I am sure that I will have a few more questions and theories to try out on you but all thoughts and assistance will be gratefully received.

 

[Dikitriki]

Hi Rob

No, I don't mind you linking to my RMweb thread at all.

Remember that I used the Sans Pareil valve gear and not Laurie Griffin's, so there are some differences in the approach to the castings.

In fact in my set the slidebar and cylinder end centres are already set as part of a one-piece casting as is the slidebar support block casting. This block in my build was crucial as it has some anchor points for part of the valve gear. I just set the crank centres from these.

For the LG example you have, you have to use the centres from the curved guide block. I would not cut the curved slides back yet until you know how much movement you have in the equivalent of the expnsion link (I've seen this described as the vibrating link)

You will need to fabricate a motion bracket to support the slidebars. I should imagine that the anchor links will be attached to brackets on the motion bracket, but I don't know.

Good luck!

Richard

 

[7mmMick]

Hi Rob,

I'm no expert here at all but I too am building NER joy valve gear at the moment for my J73 using the same LG parts. The anchor link in mine is attached to the bottom of the motion plate and I was hoping to use the same brackets as you describe to do this. I am yet to fabricate the motion plate but again as Richard says this will be put together as per the GA but with the dimensions of the slider bracket in mind. To be honest I'm working mainly off the GA and its dimension already differ slightly to what Laurie's instructions describe. I sought his advice on this and he said it shouldn't be an issue. I look forward to your progress as it will help me out no end mate,

Cheers mick

 

[Rob Pulham]

Hi Rob

No, I don't mind you linking to my RMweb thread at all.

Remember that I used the Sans Pareil valve gear and not Laurie Griffin's, so there are some differences in the approach to the castings.

Thanks Richard,
I was aware that you had used the Sanspariel castings but neglected to mention it

For the LG example you have, you have to use the centres from the curved guide block. I would not cut the curved slides back yet until you know how much movement you have in the equivalent of the expansion link (I've seen this described as the vibrating link)

Sorry but what do you mean by "you have to use the centres from the curved guide block."
Is this what you are referring to - or am I missing something? This is an extract from Laurie's instructions

You will need to fabricate a motion bracket to support the slidebars. I should imagine that the anchor links will be attached to brackets on the motion bracket, but I don't know.

Thanks also for clarifying that I will need to make a motion bracket - I thought I would, but with it only being mentioned in passing and some of the instructions leaping about from NER to LNWR I wasn't 100% certain. I have some brass strips in stock that will make one almost as sturdy as your lovely casting.

 

[Rob Pulham]

Hi Rob,

I'm no expert here at all but I too am building NER joy valve gear at the moment for my J73 using the same LG parts. The anchor link in mine is attached to the bottom of the motion plate and I was hoping to use the same brackets as you describe to do this. I am yet to fabricate the motion plate but again as Richard says this will be put together as per the GA but with the dimensions of the slider bracket in mind. To be honest I'm working mainly off the GA and its dimension already differ slightly to what Laurie's instructions describe. I sought his advice on this and he said it shouldn't be an issue. I look forward to your progress as it will help me out no end mate,

Cheers mick

Hi Mick,

It's slightly reassuring that if you are working from the GA and the anchor link is attached to the motion plate then the chances are that mine will too (when I get the blessed GA).

It also mentions making a reversing lever, do you plan to make that from scratch?

Apart from cutting out and cleaning up the castings I will be concentrating on getting the rest of the chassis sorted while I await the drawing, although I may have a go at the cylinder back plate/motion plates depending on how far I get.

I do hope to have more time to spend on this now that the garden is sorted.

 

[Dikitriki]

Sorry but what do you mean by "you have to use the centres from the curved guide block."
Is this what you are referring to - or am I missing something? This is an extract from Laurie's instructions

View attachment 24640

Hi Rob

This is the piece I meant



The sliding components are directly above the connecting rods, It follows that the centres on the curved guide block (which I presume is a one-piece casting) must be equal to the crank centres and the slidebar centres - in your diagram attached, 14mm. What are the centres of the curved guide block?

Cheers

Richard

 

[7mmMick]

Rob,

Richard is bang on, the slide block is a one piece casting so the rest of the gear needs to line up with that as per the dimensions in the instructions. Although I would wait to get the GA before you crack on as mine (J73) is slightly different as the valve chests are higher than what the instructions refer to (I think they're based on a J21). The cut off in this gear is set by the angle of the sliding block and a rod runs from this to the lever reverser in the cab. All I intended to do is use some either 1mm brass strip to represent this or some scrap etch, whichever is more suitable. If should only take a short section as the tanks hide a lot if it. It is difficult to get your head round how this gear works, there are no eccentrics and it looks really weird when in motion. I took a video of Laurie's J21 on his stand and I keep having to watch it to get my head round it, I'll
post here if it helps.

Finally Richard is the man to talk to with regards inside motion as he's built lot and it works beautifully,

ATB Mick

 

[Dikitriki]

Hi

There's a 20 second video clip of my Aspinall A Joy valve gear here:

Cheers

Richard

 

[Dog Star]

There's a 20 second video clip of my Aspinall A Joy valve gear here:

Oooohhh - so nice, so very nice.

 

[Rob Pulham]

Hi Rob

This is the piece I meant

View attachment 24641

The sliding components are directly above the connecting rods, It follows that the centres on the curved guide block (which I presume is a one-piece casting) must be equal to the crank centres and the slidebar centres - in your diagram attached, 14mm. What are the centres of the curved guide block?

Cheers

Richard

Thanks again Richard,

I did wonder (having further thoughts) after I posted the question if that's what you were referring to - I remembered about the curved sections that need cutting and fitting to it.

 

[Rob Pulham]

Thanks Mick,

It was the little cranked reversing arm that is shown attached to the slide shaft in Laurie's diagrams as opposed to the bit going to the cab (if that makes sense?).

It's nice to know that I am not on my own in this little endeavour , I am sure that we will get both sets working in the end.

 

[Steph Dale]

Rob,

I've not built a set of Joy valvegear, nor does it appear that I'll have to in the foreseeable future, but I have built a number of sets of Stephenson. I've had a quick look at some of the key dimensions I'm currently using with the Laurie Griffin parts, in the hope of offering some useful information.

Crank axle:
Crank centres 13mm
Width over cranks 19.5(ish)
This gives the opportunity to use hornblocks, thinned to 2mm and an internal frame dimension therefore of 24+mm, this avoid the crank axle clonking on the hornblocks. Note no sideplay on the crankaxle, otherwise the big ends will bind in the cranks.

Cylinders/valves:
Cylinder centres vary and are in the range 14-15mm, depending on prototype and model clearances - 0-6-0 locos typically use the smaller dimension to allow for clearances around the hornblocks and slidebars.
The slidebars seem to be about 7.5mm wide, so a 14mm cylinder/valve centre leaves you plenty of clearance inside the frames; the width across the slidebars is roughly 21.5mm.

Frame width:
In my 2251 (the only loco to hand which has valvegear and I know runs well through 6' curves) overall frame width is 26.5mm, sideplay is only on the first and last axles. With 0.030" frame material frame spacers are therefore 25mm - which could give tricky slidebar/hornblock clearances around the front axle of an 0-6-0 were it not for the fact that this loco has 2-bar slidebars, not 4-bar. I suspect you won't have a problem in this area as your loco won't have hornblocks to worry about.

General notes:
Connecting rods have to run parallel to the frames, otherwise they'll either look daft (with an s-curve in profile) or jam in the cranks or slidebars. To get round the dimension mis-match between the crank centres and cylinder centres, I off-set the little end of the con-rod in the crosshead. This shot from my 2251 build shows it quite clearly:

I suspect that you'll find you have to off-set the rod that drives off the con rod to overcome a similar alignment issue.

Needless to say, all the subterfuge is pretty much invisible once the boiler is in place and you can't look straight down on the frames and motion!

Steph

Hmm, just read that back; I suspect it's all utter gibberish...

 

[Rob Pulham]

Thanks for the contribution Steph, it's all food for thought.

 

[7mmMick]

Rob,

I've not built a set of Joy valvegear, nor does it appear that I'll have to in the foreseeable future, but I have built a number of sets of Stephenson. I've had a quick look at some of the key dimensions I'm currently using with the Laurie Griffin parts, in the hope of offering some useful information.

Crank axle:
Crank centres 13mm
Width over cranks 19.5(ish)
This gives the opportunity to use hornblocks, thinned to 2mm and an internal frame dimension therefore of 24+mm, this avoid the crank axle clonking on the hornblocks. Note no sideplay on the crankaxle, otherwise the big ends will bind in the cranks.

Cylinders/valves:
Cylinder centres vary and are in the range 14-15mm, depending on prototype and model clearances - 0-6-0 locos typically use the smaller dimension to allow for clearances around the hornblocks and slidebars.
The slidebars seem to be about 7.5mm wide, so a 14mm cylinder/valve centre leaves you plenty of clearance inside the frames; the width across the slidebars is roughly 21.5mm.

Frame width:
In my 2251 (the only loco to hand which has valvegear and I know runs well through 6' curves) overall frame width is 26.5mm, sideplay is only on the first and last axles. With 0.030" frame material frame spacers are therefore 25mm - which could give tricky slidebar/hornblock clearances around the front axle of an 0-6-0 were it not for the fact that this loco has 2-bar slidebars, not 4-bar. I suspect you won't have a problem in this area as your loco won't have hornblocks to worry about.

General notes:
Connecting rods have to run parallel to the frames, otherwise they'll either look daft (with an s-curve in profile) or jam in the cranks or slidebars. To get round the dimension mis-match between the crank centres and cylinder centres, I off-set the little end of the con-rod in the crosshead. This shot from my 2251 build shows it quite clearly:

I suspect that you'll find you have to off-set the rod that drives off the con rod to overcome a similar alignment issue.

Needless to say, all the subterfuge is pretty much invisible once the boiler is in place and you can't look straight down on the frames and motion!

Steph

Hmm, just read that back; I suspect it's all utter gibberish...

Hi Steph,

Loads of useful bits of information there for both Rob and myself thankyou. I'm hoping I won't have to offset the connecting rods in my build as I have a bit more room between the frames. Interestingly even with S7 frame width the horn blocks I've used still need some thinning down! I'm almost ready to begin co stricton of the motion so I'll hopefully post some progress on my WB soon,

ATB Mick

 

[Dikitriki]

Hi Steph,
I'm hoping I won't have to offset the connecting rods in my build as I have a bit more room between the frames.
ATB Mick

I don't see how you can offset the connecting rods with Joy's valve gear, since the valves are driven off the connecting rod, and the valve glands, slidebars, crossheads and cranks must all be in line.

Richard

 

[Steph Dale]

Richard,

On the prototype, yes, but looking through my dimensions I wonder if there's a wriggle necessary somewhere to allow for the Laurie Griffin parts.

I'm advocating that the valve glands, slidebars, crossheads all be in alignment (Laurie quotes 14mm, so that seems fair enough) I'm assuming that the part you circled in red in post #6 has a 14mm centre distance. If it doesn't then the valve glands, slidebars, crossheads will need building to matching centres.

However, I don't see a problem currently with having the cranks and con rods on 13mm centres. This gives clearance between the frames for hornblocks and sideplay on other axles. You'd need an offset in the crosshead and potentially one in the vibrating link from the connecting rod. (Attach it as a plain link on the outside of the con rod?). All the other rods could then be spaced according to the cylinder/valve centres.

Mind you, my initial post did say:

I've not built a set of Joy valvegear, nor does it appear that I'll have to in the foreseeable future...

so I may be pontificating around the proverbial.

I'll be interested to see how it all fits in place if the dodges I usually employ are declared out of bounds.

Steph

 

[Dikitriki]

Hi Steph

I'm going to have to disagree with you. If you look at the following photo, there are too many sliding components that have to be kept in line driven off the coupling rod to kink anything. Clearances are minimal and everything has to run in the cast slides.



Yes, you could kink the coupling rod behind the gubbins, but wouldn't that look awful?

Richard

 

[Steph Dale]

Richard,

I'm not advocating kinking anything and recognise that it would cause problems, both in terms of clearance and appearance. Despite the offset in the little-end/crosshead of my 2251 there's no kink and the dodge is all but invisible; once the boiler is in place there's no way to even check.

Here's a sketch showing how longitudinal rod centres can be transferred without kinking. Actually, looking at your example above I can now see that putting such an offset into the vibrating link would definitely work, what I had missed is that the bottom anchor of the vibrating link may need to be carried out to the same spacing:



Steph

 

[Steph Dale]

And, just for the record. here's a sketch of how the off-set in the vibrating link might work to maintain clearances. The solid hatch is the connecting rod,the line hatch is the valve rod. In the left hand view the whole lot is in line, in the right hand view the connecting rod is offset by the internal width of the combination lever:


This sketch corresponds with a section taken through the blue line marked on Richard's photo:


Actually, just noticed a problem. There's no fixed terminology for Joy's valvegear. I've just downloaded three diagrams from t'net and noticed that they all use a different nomenclature, dammit.

Steph

 

[Dikitriki]

Hi Steph

I see where you are coming from now. I shall put that aside for future reference as I have at least 3 more sets of Joy valvegear to build, and I don't know what problems I shall run into.

Yours

Richard (retiring gracefully)