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Post by Shawki Shlemon on Jan 15, 2008 3:10:19 GMT
Hi All I have been for many years playing with this project on and off trying to build a 7.25" G Rocket . I only have a GA plan of the replica and want to build the type as in the Rainhill trials and want the engine to be reliable ,run and stay on the track .To achieve the objectives and don't loose the character of the engine was a hard job . So far I think (!!) I have done OK as you see in the photo which I want to share with you .There are the following to do ,the cylinders , valve gear ,cross head pump ,cross head and connecting rod etc.. also there is th manometer and few more items to do .All comments of all kinds are welcome and could be helpful .
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steam4ian
Elder Statesman
One good turn deserves another
Posts: 2,069
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Post by steam4ian on Jan 15, 2008 7:37:05 GMT
G'day Shawki.
Bonza! Is that port wine in the cask on the tender?
Are you going to fire it with coke like the original?
When do you anticipate finishing? I will be in Sydney mid April and would love to see it.
Regards, Ian
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Post by ron on Jan 15, 2008 10:29:50 GMT
Shawki, that looks great, here's a picture of the full size replica in the NRM in York, the other side has been sectioned, I think they also have a full size working replica? Ron
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Noddy
Statesman
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Post by Noddy on Jan 15, 2008 10:42:52 GMT
Shawki, that looks fantastic. Thanks for sharing it.
I think the working replica is at Beamish Museum (long time since I've been there though) Keith
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paul
Member
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Post by paul on Jan 15, 2008 11:31:13 GMT
Shawki, that looks great, here's a picture of the full size replica in the NRM in York, the other side has been sectioned, I think they also have a full size working replica? Ron I have a close up photo (taken last Feb) of the sectioned cylinder if you want it for reference?
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Post by spurley on Jan 15, 2008 19:36:22 GMT
The 'working' replica is presently undergoing overhaul and boiler replacement, not entirely sure where could even be at York. Apparently the one fitted, and the one we are all used to, is not quite correct for the working prototype. I'd like to know who's old enough to know that! I was lucky enough to have a day of play with the replica during it's visit to the Bluebell in 1982. The valve gear operates off a form of loose eccentric which slides on the axle engaging with a forward or reverse gab and operates the valves through the links visible in Ron's picture. The idea was before reversing to slow the engine down and tread on a pedal to slip the eccentric across ready to move off in reverse. The fun bit came if you got it wrong, you then had to disengage the links and work out where steam was needed and operate the valves by hand, using the two handles again visible above, until she moved off. You could then re-engage the links once underway. Good fun to set the engine competely wrong before letting the next driver have his go! ;D See how well he understood double acting cylinders Cheers Brian
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Post by GeorgeRay on Jan 15, 2008 20:36:19 GMT
Brian. I seem to remember the problem was getting the gear back from reverse into forward. Particularly when running back into the platform from the Horsted up yard head shunt. This was the only way of stopping because the emergency air-brake was only good for a couple of applications before the reservoir was empty and it then required access to an air compressor to recharge it. To get into fore gear required stamping on the pedal and moving it sideways to lock it into position the sideways movement slid the loose eccentrics sideways against the spring designed to make it easy to get into reverse. My success rate was about 50%. I found 'getting the gift of the gab' was far easier than getting into fore gear.
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steam4ian
Elder Statesman
One good turn deserves another
Posts: 2,069
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Post by steam4ian on Jan 15, 2008 21:26:55 GMT
G'day all. I think I have seen what is left of the original in the Science Museum at Kensington, so I guess this may/may not give some indication of the boiler details.
Regarding gab gear. At Blists Hill Mill Museum there is a small winding engine with gab gear. The engine has no reverse, forward is in the up direction with the bucket weight intended to reverse the winding drum. To reverse the engine the eccentric rod, with gab, was lifted off the catch on the valve spindle and parked on a slide. The valve spindle was then moved by a hand lever. The operator had it down to a fine art, made it look so simple. He was quite a character and such a simple engine drew a large fascinated crowd.
For the Rocket, what is the original valve gear? I am sure that has also undergone modification over the years so what is there on the replica now is probably a 1920's interpretation. For me I reckon the original would be something like the system on the Blists Hill Mill engine only with a slip eccentric. There are legends that the old drivers could hand manipulate the valve gear up to track speed when showing off.
Regards, Ian
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Post by spurley on Jan 15, 2008 21:28:18 GMT
Hi George
That's right, I spent one day with Lewis and we both did our best to set the engine the worse for each other. Mind you we did behave when Robert Hardy came for a ride! I particularly enjoyed the run up from Sheffield Park to Horsted in the morning though. It certainly felt exposed with only the water pipes to grab onto at the odd dropped joint! John Bellwood settled himself in the tender, he had the right idea!
Cheers
Brian
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Post by chris vine on Jan 15, 2008 22:55:35 GMT
Hi Shawki,
I understand the original, with her highly inclined cylinders, had a tendency to rock from side to side with the thrusts from the pistons. She was later modified with the cylinders much lower down, to reduce this vertical component of the thrust.
I wonder if I am correct in all this, and also if your model will have the same rolling Gait??
A farmer friend in Kent build a model of the Invicta (LBSC Canterbury Lamb) in 7.25" Gauge. Again this has high cylinders so to stop the rolling motion, he omitted any suspension on the driven (rear) axle. It works fine and never comes off the track despite a totally alarming turn of speed!
PS Spurley and others are very lucky chaps to have been allowed to "play" with all the engines on the Bluebell! Jealous? Me? (I would type that in green if I knew how)
Regards Chris.
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simonwass
Part of the e-furniture
Cecil Pagets 2-6-2 of 1908. Engine number 2299. Would make a fascinating model....
Posts: 472
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Post by simonwass on Jan 16, 2008 0:11:25 GMT
Jealous? Me? (I would type that in green if I knew how) Regards Chris. What, like this?Or this?There is a colours (colors!) box an inch above the top right of the message box, select your colour and write between the ][ marks. Just click on preview to see if you've got it right.
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steam4ian
Elder Statesman
One good turn deserves another
Posts: 2,069
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Post by steam4ian on Jan 16, 2008 2:30:31 GMT
G'day Chris.
Is that "Bongo" green? Perhaps you could write a post "How not to colour text"!
regards Ian
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Post by Shawki Shlemon on Jan 16, 2008 5:26:01 GMT
I am glad to start this thread as it has created the desired memories and discussion . A few answers for some points :- 1) The engine will take some time to complete as I have other projects under construction and I have to design and make all the parts for cylinders etc.., but Ian you are welcome to come for a drink and peep on my work ,send me a PM if interested . 2) I will have simple slip eccentric and no GAB part in it , easier to operate as i mentioned above the engine has to work and be practical . 3) For rocking part I have used similar idea as mentioned above but in reverse ,I have done away with the suspension for for the front wheels .Time will tell . 4) Yes Paul please put the photo on the thread for the benefit of all as well as me .
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Post by chris vine on Jan 16, 2008 9:49:59 GMT
Hi Simon and Ian, Very Bongo not green......
Shawki, the effect will be the same for you as the drive is onto the front axle in your case. I think it is a sensible precaution.
Chris.
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dscott
Elder Statesman
Posts: 2,438
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Post by dscott on Jan 16, 2008 11:40:45 GMT
Hi Shawki, What a lovely model, and in 7 1/4", I was looking at the photo on the wall behind as well, Talking of paint, I had to laugh when I read that during the blue paint era the push bikes seemed to match the engines at Swindon!!. Well In about 1980 I visited the celebrations on the Liverpool and Manchester railway and saw the other replica running, together with the other contestants. An interesting fact came to light during the modern casting for the opposition!! in that it was incredibly difficult due to the length of steam passages and cores in the original cylinder design, that enabled the Rocket to win the 500 pounds. The debate continues. David.
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Post by GeorgeRay on Jan 16, 2008 20:23:51 GMT
The working replica that Brian and I have worked has a slip eccentric driven valve gear which I am pretty sure is as built. The eccentric has to be moved sideways to disengage it from the drive dog when changing direction on the move. If you don't succeed in doing this before you come to a stand then you have to revert as Brian said to disengaging the gabs and working the valves manually, having first worked out which valve needs to be moved and in which direction, until the eccentric picks up for the direction you are now moving in, you then have to try and re-engage the gabs on the valve rods as the loco moves. It was great fun, but the force required to actually open and shut the valves was quite high. Opening the valve usually resulted in a great lurch to one side or the other as the piston took steam, shutting the valve and opening the next one produced a lurch in the other direction, by now hopefully you were moving and it was then a case of easing the valve rod gab down onto the engagement pin. The two valve operating levers are the shiny ones pointing downwards on Rons picture and the handles for operating the gabs are just an extension of the valve rod and point upwards crossing over Mallards nameplate and handrail.
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Post by Shawki Shlemon on Jan 17, 2008 0:49:19 GMT
Hi George
after a long and hard taught I decided to make the valve gear just slip eccentric and skip the Gab part , move the loco forward a little bit and it will be in fwd gear and vice versa , I did that on the Lion and works great ,it is a compromise but I am a practical person .
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Post by GeorgeRay on Jan 17, 2008 11:53:25 GMT
Hi Shawki Its a little difficult to give it a push in the right direction in full size. Although that might have been easier than pumping the valve levers up and down trying to get it to move in the right direction. Uncoupling from the train and using a pinch bar to move it would probably have been less nerve wracking. Even in 15" gauge I guess you could dispense with the gabs and give a push to get going so that is obviously the right way to go for a model. Best of luck in finishing it.
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paul
Member
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Post by paul on Jan 17, 2008 23:16:16 GMT
Have a bit of this...
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Post by Shawki Shlemon on Jan 17, 2008 23:39:48 GMT
Thank you Paul for the the picture , every little information helps in producing the final product . George , I am glad that you agree with me on the valve gear , as I said I did the same with the Lion and the result was fantastic .
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