Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Steam => Topic started by: UKJonathan on October 19, 2009, 12:06:58 pm
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Hi can anyone tell me where I could get a gearbox so I can get reverse on my Stuart turner twin launch engine ?
Thanx
Jonathan
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Hi,
Try this link to Mainsteam Models:
http://www.mainsteam.co.uk/gearboxes.htm
Ian.
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Mainstream use a car gear box by the looks of thing with a brass cover it looks like the HPI Savage reversing gearbox for a IC buggy so it has plenty of strength about £29 they need a servo but the engine does not need to slow right down. the HPI one has been used by a lot of modelers for reverse on steam engines.
Peter
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Thought about a reversible pitch prop Jonathan ??
regards ian.
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hi Ian,
what is a reversible pitch prop ?? I am new to this and still finding my feet. Also the buggy one sounds interesting and cheap. I don't mind using a a servo to change from forward to reverse if that is how it works.
jonathan
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Hi Jonathan,
Could you not get the reversing gear castings for your engine then hook a servo up to the engine direct?
Greg
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Hi Greg,
not sure where to get them and I don't have any expereance in milling them if they need it.
jonathan
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Hi Jonathan,
Stuartmodels.com (http://Stuartmodels.com)- Go here and follow links to Reverse Gears & Feedpumps- listed as Reverse gears for Twin Launch.
If your looking for someone who could machine them for you get in touch with fellow member Bogstandard- he is great to deal with, fast, efficient, not overpriced at all and is a nice guy to boot- give him a PM and see what he says- he's usually more than happy to help a fellow steam nut- and he also has use of a personal machine shop so his work is top notch.
Greg
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Ive just checked the ST website for the reversing gear- and it isn't listed- because your engine should have come complete with the reversing mech' already on.
Where did you find this engine?
Greg
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hi Greg
I bought it of someone I knew but it did not have the reversing bit with it, it would be nice as I said if I could get the proper one but I'm not that clever to machine parts so I may have to look to the HPI Savage reversing gearbox route which I really did not want.
jonathan
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Sorry for delay Jonathan, R/P prop is one where you can go from forward to reverse by allowing the prop blades to be swung from posiitive to negative pitch mechanically without a change in engine speed or rotation. Send a me P/M with your E-Mail address O0 :-))
You don't state which twin launch engine you have? It must be the Later S/T engines that have the reversing gear (Stevenson's Launch Link) on the Double Ten, if it is that one, fitted as standard as the original engine castings were NOT supplied with this feature and it was many years before an additional kit was produced and sold as an extra. (Long before Vale took over)
Regards Ian
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If you are interested in gearboxes, this site may be of use to you.
http://members.tele2.nl/s_weggeman/CT.htm
It's a well put together site.
Usual disclaimers apply.
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Hi Jonathan,
Could really do with a pic of the engine and boat then we could really give you tailored advice.
Greg
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Hi Greg here is a couple of pics first time so hope they come on
jonathan
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Hi Greg
sorry but two same here is another
Jonathan
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If you go down the HPI gearbox route ( they are quite small and easy to use) and at £22 cheap as chips
http://www.rcpitstop.co.uk/hpi-savage-reverse-module-hp87032-39-p.asp
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Hi
If I used the HPI gearbox then I have been told I have to shorten one side as the shaft is too long because the reverse shaft is around the long shaft. I just have to mill the prop fittings a little larger so I am told.
jonathan
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you just shorten the shaft, and bore out the coupling OR use the car bits.
peter
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Don't go down, what appears to be, the complicated route of fitting a reversing gearbox to a steam engine. ALL steam engines, that I know of, both model and full size reverse by stopping and then reversing the complete engine using the reversing lever. Even on full size steam locos and traction engines reverse is obtained in this way. Some traction engines/road locos have a 3 or 4 speed gearbox but the appropriate gear is selected whilst the vehicle is stationary and then the regulator is opened to start moving. This system gives the same number of speeds in reverse as in forward. I have no doubt that full size steam propelled boats operate via the same principle. The reversing gear is all part of the engine and, in the case of a model boat, is operated by a servo moving the reversing lever through the sequence forward-neutral-reverse and vice versa. I think you would regret it if you started chopping your engine about to fit a reverse gearbox.
Hope this is of some help :-)).
Derek. :police:
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hi there
Derek
I am afraid its looks as though the gentleman has to go down the road of fitting a reversing gearbox to the steam engine; with the photographs he has put on I cannot see any evidence of any secondary reversing concentrics on the crank shaft. There is definitely no indication of a 'Stevenson's link' for the reversing system. That is just one of the few ways of reversing a steam engine - using Stevenson's link.
I have just been on Stuart Turner's website myself looking for the reversing bits. Also, out of curiosity of much these things cost. I would have to remortgage me house to pay for one - by gum I did get a surprise. O0 %%
aye
john e
bluebird
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Derek is spot on here, what you need is the Stephenson's linkage for the slide valves on your engine an additional extra that should be available from Stuart Turner and should not be too hard to fit to your engine.
I wouldn't go down the variable pitch propeller route as you will find that as the pitch is increased/decreased the load variations will cause the engine to speed up and down and especially at zero pitch the engine will race away as there would be very little to no load present, unless you can include some sort of governor or regulator to control the steam flow in sinc with the props pitch, this I think would be a very complicated system.
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Hi John (Bluebird),
I appreciate what you say but I have never come across a Stuart Turner launch engine that does not have a reversing system. This looks like a nicely built engine and I would be surprised if it was not designed to have a means of reversing it.
Derek. :police:
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Hi just a passing thought no body has mentioned a Kitchener rudder for reversing
aye
john
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Hi,
First of all Jonathan you would find it impossible to fit any reversing gearbox after the engine- you simply havn't got any room!!! Your shaft is going to be at a really daft angle to start with!
Secondly- contact ST and tell them you have an old design twin launch engine without reversing gear- ask them if they could send the reversing castings as spare parts. Next contact Bogstandard via PM and enquire if he will machine them for you-i'm sure he will- if not someone at your local model engineering club may do it for you.
Lastly- Stephenson's link is far from being the only, the best, or the most suitable for this engine (although that is what the majority of engunes are fitted with, and is indeed what ST supply with the Twin Launch now).
The most suitable for this situation would be a slip eccentric arrangement (extremely hard to make in model sizes), next a Kitchen rudder would be very viable in this boat- plenty of room in the counter stern to fix the arrangement, and lastly a reversing pitch prop' (although these too are quite hard to make).
Greg
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Don't go down, what appears to be, the complicated route of fitting a reversing gearbox to a steam engine. ALL steam engines, that I know of, both model and full size reverse by stopping and then reversing the complete engine using the reversing lever. Even on full size steam locos and traction engines reverse is obtained in this way. Some traction engines/road locos have a 3 or 4 speed gearbox but the appropriate gear is selected whilst the vehicle is stationary and then the regulator is opened to start moving. This system gives the same number of speeds in reverse as in forward. I have no doubt that full size steam propelled boats operate via the same principle. The reversing gear is all part of the engine and, in the case of a model boat, is operated by a servo moving the reversing lever through the sequence forward-neutral-reverse and vice versa. I think you would regret it if you started chopping your engine about to fit a reverse gearbox.
Hope this is of some help :-)).
Derek. :police:
Derek have you used one of these boxes on a model steam plant or seen one in operation ???do you run steam boats? do you think I would propose a member to spend money if it did not work in this situation ?? one you don't have to stop the engine to go in reverse I know because i fitted one to A single that would not re start I am fitting another now to a single, you don't have to chop the engine about to do this you just connect to the box the same way you would to a prop shaft , i wish people on this site would stop saying things wont work until they have tried it or have first hand knowledge, and there is no reason not to put ideas forward but to tell people who have done it it wont work is a pain
Peter
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Peter,
I will not make any comment except that I was trying to be helpful. I appear to have upset you and that was never my intention so - nothing further to say.
Derek.
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Peter,
I will not make any comment except that I was trying to be helpful. I appear to have upset you and that was never my intention so - nothing further to say.
Derek.
sorry for Jumping ,
Peter
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Hi Greg,
The pics I put on and the way I took them make the engine look almost touching the rear but it is not as near as it looks here is a better pic showing scale although taking pics seem to compress the size. Also I think I am going to go down the HPI route I think,
Jonathan
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This is a part of the PM I'm sending to you Jonathan, but putting it on here so that others may be able to see that it is in fact Stevensons that S/T show fitted to the "Old" Launch Twin. You will also notice that you haven't got the cylinder drain cocks fitted either, though how you would link them and operate whilst the boat is in the middle of the pond would require a REALLY powerful servo.
http://www.stuartmodels.com/inprod_det.cfm/section/casting/mod_id/63 (http://www.stuartmodels.com/inprod_det.cfm/section/casting/mod_id/63)
It seems the original maker wanted to use this in a vessel opposed to haveing a "Bling Queen", as linking and operating Stevensons is not impossible, but is more difficult than a piston valve engine with a reversing lever. Yes they have been and are used, but sliding the quadrent over is wasted thirty feet away. Far from "Should have come with reversing gear fitted", if you look down the page on the second link, it clearly states "Items NOT supplied with the KIT" which again suggests the builder wanted to play rather than look.
http://www.stuartmodels.com/pdfs/Twin-Launch-Parts-List.pdf (http://www.stuartmodels.com/pdfs/Twin-Launch-Parts-List.pdf)
T'ony problem with the boxes that Peter (NOT having a go) is suggesting is that it's a "Crash" box or looks to be, ie. no clutch, and Engaging it into reverse without slowing the engine although not TOTALLY detrimental will chuck a splash or two, just like has been said to criticise the reversable prop??
Any road, scans will be on their way shortly.
Regards Ian.http://
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Hi Circlip,
Just wondering about a couple of things you point out-
1st,
This is a part of the PM I'm sending to you Jonathan, but putting it on here so that others may be able to see that it is in fact Stevensons that S/T show fitted to the "Old" Launch Twin. You will also notice that you haven't got the cylinder drain cocks fitted either, though how you would link them and operate whilst the boat is in the middle of the pond would require a REALLY powerful servo.
Why would drain cocks require a really powerful servo? If oiled and eased they should turn with the slightest touch.
2nd,
It seems the original maker wanted to use this in a vessel opposed to haveing a "Bling Queen", as linking and operating Stevensons is not impossible, but is more difficult than a piston valve engine with a reversing lever. Yes they have been and are used, but sliding the quadrent over is wasted thirty feet away. Far from "Should have come with reversing gear fitted", if you look down the page on the second link, it clearly states "Items NOT supplied with the KIT" which again suggests the builder wanted to play rather than look.
http://www.stuartmodels.com/pdfs/Twin-Launch-Parts-List.pdf (http://www.stuartmodels.com/pdfs/Twin-Launch-Parts-List.pdf)
It seems the original maker didn't have a clue to make a useable steam engine- good workmanship aside!!!!
The quadrant if fitted with a double quick threaded reversing wheel can be turned with a decent sail winch servo motor- who said it has to be lever controlled?
Lastly, it clearly states on the link you posted;
STUART TWIN LAUNCH PARTS LIST
8 (RG) 24201 ECCENTRIC SHEAVES CAST IRON 2
3 (RG) 24202 ECCENTRIC RODS GUNMETAL 4
18 (E) 24280 SLIDE VALVE GUNMETAL 2
9 (RG) 24203 SLIDER BRACKET GUNMETAL 1
MATERIALS NOT INCLUDED IN THE KIT
5 (RG), 12 (RG) MS140 DRAG LINKS, ANCHOR ROD BKT. MILD STEEL 1⁄4" sq x 3" 2
7 (RG) MS192 REVERSING LEVER MILD STEEL 3⁄8" x 5⁄8" x 5 1⁄2" 1
2 (RG) MS207 EXPANSION LINK MILD STEEL 1⁄8" x 1" x 2" 2
(RG) 24656 EXPANSION LINK PINS MILD STEEL 1⁄32" O WIRE 1
5 (E) SS225 VALVE RODS STAINLESS 1⁄8" O x 2 3⁄4" 2
Then also included in the kit are;
STUART TWIN LAUNCH FIXINGS LIST
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PINS 25051 REVERSING LINK MILD STEEL 1⁄16" O x 1⁄2" 1
BOLTS 71703 ECCENTRIC RODS MILD STEEL 7BA x 3⁄8" 4
BOLTS 71707 CONNECTING ROD MILD STEEL 7BA x 5⁄8" 4
BOLTS 71707 ECCENTRIC STRAPS MILD STEEL 7BA x 5⁄8" 8
BOLTS 71708 DRAG LINKS MILD STEEL 7BA x 11⁄16" 4
NUTS 71755 ECCENTRIC STRAPS MILD STEEL 7BA 8
NUTS 71755 ECCENTRIC RODS MILD STEEL 7BA 4
NUTS 71755 DRAG LINKS MILD STEEL 7BA 4
CSK SCREWS 71787 SLIDER BRACKET MILD STEEL 7BA x 1⁄4" 8
GRUBCREWS 71825 ECCENTRIC SHEAVES MILD STEEL 7BA x 1⁄8" 2
GRUBCREWS 71825 SLIDER BRACKET MILD STEEL 7BA x 1⁄8" 2
Quite clearly you can see that most of the materials and fixings require ARE included in the kit, including most importantly, 4 off eccentric rods.
Greg
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Hi,
I tried a couple of methods of drain valve operation on my Stuart D10.
The first method utilised the Stuart drain cocks, but with their handles modified to mate with a common linkage so that one servo would operate the four drain cocks at once. The problems I encountered were aligning the linkage with all four cocks for smooth operation and also the valves unscrewing from the cylinder if they were not perfectly aligned.
For the second method I made a sleeve valve with four inlets exhausting through a common stainless steel tube with the outlet at the end. The cylinder drain ports were then connected to the sleeve valve with 1/8th OD copper pipe. The valve spindle was linked to a cheap £7 servo.
This performed very satisfactory under remote control, but in practise I found I was only using it on the initial start up. As an experiment, I have blanked off the cylinder drains altogether and now just joggle the reversing gear to dump condensate on startup.
If you use servos on steam plant ensure there is sufficient linkage length between the hot parts and the servo to prevent the plastic gears from melting (it happened to me!).
For the reversing gear servo, I did resort to an expensive high torque servo with metal gears and a 2:1 ratio lever, because of the back reaction of the reversing gear as the eccentrics moved.
Ian G.
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I bow to your superior knowledge Gondolier, although as a double acting twin cylinder slide valve engine, I would have expected there to be 2 eccentric sheaves and also 2 slide valves included, O0 :-)). There are far more bits pertaining to the reversing mechanism not included than you have shown, but hey, it's a moot point really despite them including a few extra nuts a bolts. Stuarts, including the original owner seem to sell reversing gear as an extra, so perhaps the extra bits in the kit are just like a supermarket "Loss Leader"??
Hope all the bits got through Jonathan, you now have three avenues to look at.
Your photo's Ian G are as interesting as ever, many thanks.
Regards Ian.
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Hi Ian and all,
first thing I have to do is thank you all for your input, and outlining my options. I will mull over them and I am quite sure I will come up with the right solution. The good thing is having all this knowledge, at ones finger tips to tap into is really helpful. I will keep the forum informed of my decision.
Jonathan