Just to introduce myself Modelworks 9F restauration project.

[peterdebeus]

Made the rings today, it took exactly 2 minute 14 seconds to make 10 with 4 different sizes.
At 55 seconds you can see how you can do that this quick! 
and also some other PFTE macining at 2:20

www.youtube.com/watch?v=UdMFPafdg8w

Its a short movie to show custommers what we do (I work at a company suplying and installing cnc machinery)

[peterdebeus]

Already re fitted the pistons and now time to fit the new rings into the cylinders.
After that the most difficult job i think, setting the valve timing...

I realy have no idea where to start with, but is there a website or something where to start with?
Or maby somone can show me how they set their valve timing? as i think the cylinders from Brit and 9F are mostly the same?
So maby i can copy the valve timing to make a good start??? not sure if it works like that

[Deleted]

Hi Peter

This entry on my website www.britanniabuilder.com/kit13.htm#5408 describes how I finally set the valve gear on my Modelworks Britannia, after a lot of false starts. I had to adjust the position of the motion brackets on the frames and the length of the eccentric rods to get it right, but hopefully you will not need to do this on your 9F. I haven't heard reports of any errors in the geometry of the 9F valve gear.

Basically, if the geometry of the valve gear is correct, all you should need to do is set the angle of the return cranks and then set the position of the valve bobbins on the valve rods.

Check that you can get full travel of the reverser without the valve crosshead hitting the front or rear of its slides.

Kind regards

John

[Deleted]

hi Peter

To add to John's good advice you may also want to check out Don Ashton's website... he has helped me a number of times along with many others on this forum. www.donashton.co.uk/

Regards

Pete

[peterdebeus]

after some hours of work the PFTE rings finaly go in realy smooth (can push the bobbin in with one finger)


Just hope thats ok.....

still strugling to get the timing ok, maby time to ask an expert to check this

[peterdebeus]

New valve rings made from PFTE






Some more UK history!

[Deleted]

looks good Pete.. I have to say the new PTFE rings on my 4470 has transformed the running of the loco.. btw nice car..

Pete

[peterdebeus]

After mesuring and trying what happens i finaly get to know how everything works with the valve timing and how it should work.

I see that i need maximum stroke of the valve,front to back, otherwise the exhaust will not open.

with the timing like it was Before the exhaust wasnt opening at all....
So i set the maximum stroke by turning the angel of the return crank, that should be ok now.
Tonight i am going to make a map of the ports, with all the distance to the front face of the valve.
So i know at witch point they open... then it should be ok i guess!

[Deleted]

As a simple starting point, with the reverser set to full cut-off, if you then put the loco's main piston to either front or rear centre, the inlet should now be fully open but not overthrown....You'll have to do some calculations and use depth measurements for this as you can't see the ports with inside admission piston valves..You're on the right idea of making a diagramme of the ports etc.....That way you can "see" just what's going on in there........The setting of the valves relates to the inlet function, the exhaust settings will fall into place automatically through the design....If you can view a slide valve engine (Simplex for example) you can get a better idea because it's an outside admission and the steam chest is quite easy to view the events---- This might help}---- en.wikipedia.org/wiki/Walschaerts_valve_gear -----------

[Deleted]

Aug 7, 2013 23:57:43 GMT @4930hagley said:

As a simple starting point, with the reverser set to full cut-off, if you then put the loco's main piston to either front or rear centre, the inlet should now be fully open but not overthrown....

With the piston at front and back centre, the inlet ports should be just cracking open, NOT fully open! The amount the ports are open will be equal to the amount of lead designed into the valve gear e.g. maybe 0.020" or 0.5mm. Walschaert's is a constant lead gear so, in theory, the reverser position makes no difference to this.

You'll also find that in full gear and the return crank set correctly, the valve will travel quite a distance past the exhaust ports. You really need to carefully measure the valve gear and put the results into a simulator to see what is really happening.

[peterdebeus]

Thank you verry much for al the information.

Mister Andrew made a realy nice drawing, with the piston at front and rear dead centre, with all the mesurements in there that need to
be done, so tonight i am going to check if all the dimensions are like they should, and try to set the Crank to its position.
So that the valve dousnt move when turning the reverser up and down.

[pondok]

By the way Baggo, still really enjoy perusing your website from time to time, always an enlightening read...

[Deleted]

Aug 8, 2013 9:23:46 GMT John Baguley said:

Aug 7, 2013 23:57:43 GMT @4930hagley said:

As a simple starting point, with the reverser set to full cut-off, if you then put the loco's main piston to either front or rear centre, the inlet should now be fully open but not overthrown....

With the piston at front and back centre, the inlet ports should be just cracking open, NOT fully open! The amount the ports are open will be equal to the amount of lead designed into the valve gear e.g. maybe 0.020" or 0.5mm. Walschaert's is a constant lead gear so, in theory, the reverser position makes no difference to this.

You'll also find that in full gear and the return crank set correctly, the valve will travel quite a distance past the exhaust ports. You really need to carefully measure the valve gear and put the results into a simulator to see what is really happening.

Hello Chaps----------Oops--I've done it again..too many late night postings !!..Yes--of course, the standard definition for lead...Thanks BAGGO......Sorry PETER, good job someone is more awake than me, eh ??----------From that centre on, further rotation of the wheel will then give a full port opening ( full steam flow) which should coincide with the crank being at it's max. cranking angle ie at 90 degrees in the direction of rotation(for max. torque).....Continued rotation will see the port closing at it's minimum cranking position ( 90 degrees before the next centre)...This gives APPROX. 270 degrees rotation with steam acting on the main piston face............The animated diagrams show this quite well...

[peterdebeus]

Hello

I have been mesuring loads of stuff tonight!

I have set the crank, so that the valve dous not move at all when turning the reverser up and down.
So that should be Ok now a think.

After that i have put the engine at it rear dead centre and screwed the valve back so that the ''exhaust'' was exactly fully opend.
Then i rolled the engine forward to its front dead centre, and calculated how far the ''intake'' was opend now.
This was 0.5mm, not sure if that was exactly what mister Baggo meaned with 0.5mm???
I have not tested what happens when i roll the engine even more forward, as the track isnt any longer.
will the ''intake'' open even more from that point, of will this be also the maximum forward position?

BTW, this was all done with the engine in exactly mid gear.

[peterdebeus]

Its running on air!

I also tried to put the reverser back up half way, and it still run realy good...
Stil turns a bit heavy i could only run it for a few seconds before my compressor was empty....
It was running till about 20 PSI before it stopped turning the wheels.

Only thing i found out, there was a large amount of air leaking between the right hand cylinder blok and the valve liner.
How was the valve liner fitted to the cylinder block? i may have to take it out to see what happens....
Its the front liner part, (with the srew cap) thats leaking....

[leliev]

Before you are taking stuff off, make a temporary adjustmentmark on how the motion is set.

[Deleted]

I don't know if the 9F is the same, but I think the Black Fives had O ring seals on the outside of the liners to seal them into the cylinder block. Apparently it was very easy to damage these when fitting the liners. The liners may be retained with a grub screw somewhere.

[peterdebeus]

Hi Paul, i already did, i have put all my mesurements in the drawings, and the locations are marked with a marker.

Hi baggo, so i should take the plating off the cylinder blocks and see of there is a grub screw somewhere?
Are they just pressed into the cylinder block or srewed in there?

Thanks

[Deleted]

Hi Peter,

Just found this thread on the 9F:

Evening Star

The post by Locoworksnorth says that the valve liners are in two halves and have 3 O rings fitted. I don't think he is active anymore otherwise he would be able to advise you better.

You could take the cylinder cladding off to see if there any grub screws or similar holding the liners in place. They could just be a press fit of course or secured with Loctite which may make removing them again a bit difficult. They are not screwed in.

John

[peterdebeus]

Ok Thank you John,

I will see what i can find