Contrate and pinion gears

hollybeau
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Contrate and pinion gears

Postby hollybeau » Fri Jun 11, 2021 6:30 pm

Rummaging through my parts box of jobs to do recently I came across a set of contrate and pinion gears. For those not familiar with these they comprise a small gear with teeth cut around the perimeter (the pinion) which meshes with a larger gear with teeth cut on the inside of the circumference (the contrate gear). This particular pair came from Ultrascale . They are still available at a cost of around £5 and are made from, " injection moulded Nylatron GS." I have had them years and can't recall what I bought them for.
Obviously with a ratio of only 2.9:1 then I could not simply attach a motor to the pinion end as the gearing would be far too high. Luckily however, in the same box was a motor I had also bought years ago with a planetary set of gears attached to the head (see second photo below). There was no paperwork with this but from memory the gears reduced the motor rpm by a ratio of around 15:1. Taken together therefore the whole reduction would be around 45:1- just about ideal for my intended use (in a Midland M Class 0-6-0). For those wondering about these motors I bought a job lot some time ago from a chap in the States who was known as "Micromotorman" on that well-known auction site. The motors are all high-quality precision coreless jobs from the likes of Faulhaber and Portescap and the planetary gearboxes simply screw on the front (although I have never built up the courage to unscrew one). They are quiet and powerful. They cost from memory about £30 each, including postage from the States. I have been unable to find "the Motorman" recently and I sadly suspect he has ceased trading.
I should add that so far I have only made the gearbox and done a lash up with the motor. So far so good but I have no idea if this combination will work to drive a loco and I may well fall flat on my face. Whatever happens it promises to be interesting and different.

Construction


I began by assembling the pinion on a lay shaft of 2mm silver steel. There are no instructions with the gears and I assume that they are intended to be a tight push fit on the shaft. My first tentative attempt (from the collar end) showed some signs of cracking so I stopped, turned down the end of the shaft slightly and then re-assembled. The fit now was smooth but it slipped under pressure. Various epoxies and Loctite were tried without success (I suspect the "plastic" is too "slippery") so in the end I resorted to drilling through the collar and shaft and putting a pin in. This has held.
The "gearbox" - a rather fancy term for some bits of nickel silver left over from some etchings - was then made up. As you can see it is basically a rectangular box with a central divider. One immediate problem is that with the contrate gear so obviously fitted to one side and with the pinion needing to sit central to the chassis the width of the gearbox becomes a concern in terms of its ability to fit between the chassis members. This was particularly important to me as I also intended to use split axle construction. In the end, with the use of some drawings and mock-ups I got the gearbox down to a width of 12.2mm. Making the box was not difficult, using the technique of soldering the two sides together, cutting and filing to shape and drilling out on the centre-line for the top hat bearings. I did the same for the middle cross piece and one end: the "blank" end being soldered on last once of course the lay-shaft had been inserted. Using a 3mm "dummy" axle (i.e. one that allowed the contrate gear to slide on easily) I then fiddled with the clearances on the top hat bearings. One side had to be filed flush to allow the contrate wheel to sit up to it. The other was left alone and a piece of spacer tubing turned to fit over the rest of the axle inside the 'box. (I am not sure this is necessary as the contrate wheel is kept in pace by the pinion but I played safe anyway).
Finally, a paper washer was placed over the layshaft outside the box and a tight-fitting washer threaded on and then quickly soldered in place. removal of the paper washer left a layshaft free to rotate but with just slight clearance back and forth.

The result of all this endeavour can be seen here:
20210609_114700.jpg

Having seen this photo close up for the first time I have noticed that the central spacer appears to not be square to the rest of the 'box. I hope this will not affect the performance which so far is promising. You will also see that I have now made up a special three-part split axle with narrower than usual stub ends necessitated by the wider than usual gearbox. It was a nervous moment pressing on the axle as I clearly wanted the contrate gear to grip tightly enough so that there was no risk of slipping but equally I did not with to risk splitting it. All is well and if it does slip I can always pin it as I did the pinion wheel.

The second photo below shows the wheels mounted (my usual Gibson brass-centred wheels, left over from when I made a job lot which featured in an article I wrote for the Snooze in 2013 (Issue 181). Although I prefer to use continuous sprung beams to suspend my locos there simply would not have been enough room to accommodate these and this gearbox so I have gone with "plan B" which is Brassmasters/Comet hornblocks fitted directly into the Comet chassis sides (Also in the parts box was a set of etchings for a Comet chassis of the LMS 4F which will serve very nicely under the M Class body thanks to the Midland's policy of standardising on coupling rod centres.)
The photo also shows the motor and planetary gearbox which is to go in the tender. The motor is rather long but is otherwise quite modest in diameter.

So there you go. Where this goes from here I do not know as it is uncharted territory for me. I think I know how things will work at the engine end but how the motor is going to fit in the tender has yet to be determined. One thing is for sure , it will be fun finding out.
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Chas Levin
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Re: Contrate and pinion gears

Postby Chas Levin » Fri Jun 11, 2021 9:01 pm

Very nice work - and always so satisfying finding a use for things from the spares box that have been there so long you're not sure what they were originally intended for! :D
Chas

Crepello
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Re: Contrate and pinion gears

Postby Crepello » Fri Jun 11, 2021 9:17 pm

Theoretically, you will have a torque reaction between the loco and tender amounting to about
one-third of the driving wheel torque developed when hauling a load. (That proportion being the
approximate ratio of the final drive box.)

hollybeau
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Re: Contrate and pinion gears

Postby hollybeau » Sat Jun 12, 2021 6:31 pm

Many thanks for your comments.

Crepello: I was sort of aware of torque reaction being a potential issue. To be clear, for my benefit - and any others reading this and not familiar with the issue - I am assuming that this is the tendency for the tender (in which the motor is mounted) to try and twist (or is that turn?) along its horizontal axis in the opposite direction to the engine? Do I have that right?
The bit that was new to me is the idea that the reaction is approximately equal to the ratio of the final drive box (in this case 2.9:1). If I have understood this correctly then is it better to have all the gearing on the engine and none, or very little at the tender end? Those who have made tender drives work - using cardan shafts through to a gearbox in the engine (and there are many who have but the one that comes to mind is Steve Duckworth of this society) certainly seem to have adopted this approach.
I note that you did use the word "theoretically" suggesting that there may or may not be a problem with the tender toppling over when under load. I assume, but please feel free to correct me, that having as much weight in the tender and getting the motor as low down as possible, will help to reduce any issues.

Having said all that I have built a similar 0-6-0 to this (a Kirtley outside-framed goods loco based on a K's kit) using the same arrangement of a motor with planetary gearbox in the tender. Unlike here however that has a more conventional worm and gear arrangement (out of a Rivarossi Big Boy from memory!).
The loco is one of my best runners: smooth and quiet and will pull a house down. I suspect the heavy whitemetal bodies help to counteract any torque problems.

Here's a photo of it under construction.

2012-11-22 19.09.15.jpg
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Crepello
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Re: Contrate and pinion gears

Postby Crepello » Sat Jun 12, 2021 7:44 pm

Yes, you interpreted and extrapolated correctly. The word 'theoretically' was to avoid cluttering the comment by
enumerating the real-world impingements on the pure theory, such as friction losses.

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Horsetan
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Re: Contrate and pinion gears

Postby Horsetan » Tue Jun 15, 2021 10:39 am

A useful addition to the low-resistance geartrain armoury might be these miniature German bevels:

Source here
That would be an ecumenical matter.

bécasse
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Re: Contrate and pinion gears

Postby bécasse » Tue Jun 15, 2021 11:05 am

Horsetan wrote:A useful addition to the low-resistance geartrain armoury might be these miniature German bevels:

Source here


Indeed useful but they are so small that I suspect that creating a sufficiently accurate gear box assembly might prove a major problem. I have used a GW Models riveting tool several times in the past to create accurate gear boxes (and, indeed, for other setting out tasks).

Their website is available in English too so the link for these gears is https://www.sol-expert-group.de/1-87-model-building/Screws-and-cog-wheels/Bevel-gears-M0-2-and-M0-3/Bevel-gear-set-2-pieces-20-teeth-module-0-2::1281.html?language=en

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Horsetan
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Re: Contrate and pinion gears

Postby Horsetan » Tue Jun 15, 2021 11:49 am

bécasse wrote:
Horsetan wrote:A useful addition to the low-resistance geartrain armoury might be these miniature German bevels:

Source here


Indeed useful but they are so small that I suspect that creating a sufficiently accurate gear box assembly might prove a major problem.....


There may be applications in restricted spaces / smaller engines, especially for shunting, I'd have thought.
That would be an ecumenical matter.

Enigma
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Re: Contrate and pinion gears

Postby Enigma » Tue Jun 15, 2021 12:54 pm

Really interesting site, plenty of food for thought!

hollybeau
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Re: Contrate and pinion gears

Postby hollybeau » Tue Jun 15, 2021 6:36 pm

As you say Enigma, an interesting site. I was particularly taken with the miniature ball bearings. My concern with the bevel gears is that they are the same size and thus offer no reduction. In addition, apart from the problem of accurate meshing (less of an issue with contrate and pinion) they can be noisy I believe - witness the later Portescap/RG4 etc.

Back to the build. I have now completed the chassis, mounted the wheels and made and tried on the coupling rods. There is nothing different or ground-breaking from established techniques here but some matters may be worthy of note:

a) Because of the gearbox width and the issue with the split axles the chassis has been pushed out as wide as I dare (15.75mm inside). To compensate I have the hornblocks "thin side out" and have filed off the projecting boss. (Note brass wheels also do not have a boss around the axle hole - another benefit). I have left off the chassis spacers at the back end until it is clear how I am going to do this part of the construction.

b) With the layshaft horizontal or thereabouts the gearbox lies at or just below footplate level and will clear nicely once the springs are in place. In other words there will be nothing above the footplate at any point on the loco : plenty of room for lead. At the moment the gearbox shows behind the end of the frames but I may well thin this down, being careful with the cutting and to clear the resulting swarf out to prevent it damaging the gears.

c) I have used Markits crankpins for the first time and am impressed. They have a 10BA tapped hole in the wheel (nice and strong in a brass wheel) and 14BA for the crankpins which screw on from the front. Unlike Gibson 'pins there is no separate sleeve which reduces the chance of errors. I have everything assembled rather "tight" and the wheels still revolve nicely with no sticking or quartering issues. I also like the fact that you can easily unscrew the crankpins (to avoid damage or for painting for example) although I am not sure how well suited they would be for normal plastic wheels.

20210615_143219.jpg


I have not made a start on the tender yet as I am unsure how to do the cradle for the motor. One thought I am toying with at the moment is to do away with an inner chassis and use pin-point axles in the "outer chassis" just as you would in a six-wheel wagon. I have some Ultrascales on order (so there is plenty of time!) and although these come with plain axles I would have thought I can use pin points instead. I have some Bill Bedford sprung axle-boxes which ought to do the trick. This will clear the maximum space between the tender frames for the motor. Any thoughts?
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Winander
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Re: Contrate and pinion gears

Postby Winander » Tue Jun 15, 2021 10:01 pm

hollybeau wrote:I have not made a start on the tender yet as I am unsure how to do the cradle for the motor.


It has been suggested on here a number of times to use a bed of silicon - the kind you might use around a sink or bath. Said to provide good sound insulation. Not tried it myself and I assume a simple stirrup affair to lash it down.
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hollybeau
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Re: Contrate and pinion gears

Postby hollybeau » Fri Jun 18, 2021 6:25 pm

I am familiar with the bath sealant/silicone solution and have used it in some of my locos. What I was trying to describe was how to suspend the motor within the tender, particularly if I go with no inner chassis.

On the modelling front you will recall I mentioned at the outset that I may fall flat on my face - well it has happened. Not with the gears but in my haste to use the Comet 4F chassis underneath the Class M body (knowing that all Midland 0-6-0's had an 8ft by 8ft 6" wheelbase) I had forgotten to check other dimensions. Having tried the M Class footplate against the 4F chassis it turns out the latter is longer both front and back. I could have cut back the chassis at the front but not at the back where the gearbox would have extended behind the loco. Plan B has therefore emerged. In this I have put the M Class away for another day (the original chassis etchings are still there after all) and have decided to use the 4F chassis under - a 4F. I have ordered a body of the Midland variant from Bachmann - only £34 including postage which I think represents good value. I am told it is far better than the earlier Airfix offering but still suffers from over-sized splashers (I have an Airfix-bodied 4F already but replaced the splashers with the Brassmasters "splasher kit".) As for the tender I have one on order from London Road Models but John Redrup there tells me he is waiting on new etches so things may get delayed. Ah well, not the end of the day : you can't have too many 4F's!

hollybeau
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Re: Contrate and pinion gears

Postby hollybeau » Fri Jun 25, 2021 6:23 pm

The Bachmann body for the 4F has arrived and it is a thing of beauty. Very nice detailing and paint finish. The footplate is some sort of die cast metal with the remainder in plastic. I have so far ground out a fair bit from the inside of the splashers using dental burrs and a large carborundum disc. It has been slow work. Clearances are tight, very tight and this is a concern for potential shorts, particularly as I use DCC. I may have to resort to the Iain Rice trick of lining the splashers with cigarette paper soaked in superglue. If all else fails I can always remove the splashers entirely and replace them with the Brassmaster kit replacements. I am reluctant to do this however as there is always a problem of filling in nicely around the new work and then of course painting them to match. I suspect I would end up having to repaint the whole body which would be a shame as it is such a lovely finish. Yes the splashers are oversize but not so that they offend my eyes at least.
Here are some photos of the current situation.
20210625_141523 (2).jpg

20210625_141551 (2).jpg

20210625_142240 (2).jpg


The London Road Models kit for the tender has arrived but I think I will put this to one side for use with the M Class. I have ordered the matching Bachmann tender (oddly you can't order the tender complete you have to order the upper body, the lower body and the wheels all separately - but at the same time! - as spares. At least I did not have to buy wheels I will not need). Will see what turns up. Using this rules out the use of outside bearings so I will need to make an inner tender chassis.
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hollybeau
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Re: Contrate and pinion gears

Postby hollybeau » Tue Jun 29, 2021 6:27 pm

The Bachmann tender has now arrived. It is OK but somehow does not wow like the loco. It is entirely in plastic other than the (frankly awful) "coal" which is very shiny and is part of a die cast weight. There are also errors/omissions: no handrails at the front, the coal rails are plastic and overscale and the brake blocks are moulded in line with the frames. Still nothing there that cannot be corrected fairly easily.

20210625_144036.jpg
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hollybeau
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Re: Contrate and pinion gears

Postby hollybeau » Tue Jun 29, 2021 6:44 pm

I have now made an inner chassis for the tender. The basis of this is some etched side frames (again from the parts box) with cut outs that will suit, with some judicious filing, Comet/Brassmaster hornblocks. These of course have 1/8" axle holes so for now I have used some wheels from the scrap box of the correct diameter (and only on the front and back) just to get the thing to the correct height. When the Ultrascales arrive with their 2mm axles I will turn some brass bushes to reduce down the diameter.
As you can see I have added additional nickel silver strips to both sides. these are to strengthen the construction generally but more particularly will assist when I cut out the two narrow slots over each hornblock for the springs.
The motor is supposed to be mounted by two size 2 metric bolts into the face of the (plastic) gearbox. I don't like that idea at all with so much weight hanging off the front end. I have still used this arrangement but mainly to resist the turning movement. Most of the weight will be supported by a cradle of 15mm copper pipe left over from a plumbing job. It is the correct diameter inside for the motor and outside to fit between the frames. I used a sliver of paper under the motor when setting it up so that on final assembly some mastic can be used as discussed above.
The motor has to be as far forward as possible (so that the drawbar pivot aligns over the universal joint) and as low as possible to align as far as possible with the layshaft . Thanks to the reduced diameter of the gearbox I have this sitting on the front axle. There will be clearance once the smaller diameter axle and the springs are in place. The chassis still needs quite a bit of work to profile it to fit inside the Bachmann tender.
Here is progress thus far:
20210625_141757.jpg
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davebradwell
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Re: Contrate and pinion gears

Postby davebradwell » Tue Jun 29, 2021 7:48 pm

With 2 universals you don't need to align the ball with the tender drawbar pivot which should be a bar like the prototype with pivot each end. Hope you're not even thinking of using just one universal with sprung chassis. Thought you were mounting motor with bath sealant to reduce noise.

DaveB

hollybeau
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Re: Contrate and pinion gears

Postby hollybeau » Wed Jun 30, 2021 4:58 pm

Thanks Dave.

Can you expand on your comment please about not using one universal with a sprung chassis. It's not that I don't doubt your expertise I just wondered what the relationship or problem was.
I know I am making most of this up as I go along - which was intentional from the start and is half the fun - but I was "encouraged" to adopt this approach by none other than Mike Sharman in his "Flexichas" booklet.
On page 23 he says, " In the case of Fig 29 we show how a tender can be close-coupled on one pivot only to the locomotive, and provided the centre point of the universal's operating range is in line with the tender pivot only one joint is needed."
Here is a copy of Fig 29
img120.jpg


Of course I do not know if this is theory or practice on Mike's part (although I suspect the latter) or whether the chassis was sprung or not.

Having considered the matter further, and seeing the difficulty of achieving anything like acceptable accuracy with the one u/j and its relationship with the drawbar pivot, I am coming round to the view that two couplings would be better. There is not enough room however for two couplings as things stand. I have looked at moving the contrate and pinion gearbox onto the middle axle but because the layshaft sits on the centre line it will cause problems getting the drive shaft around (over/under) the rear axle. Short of a complete left field approach (turning the gearbox around and having everything in the loco) the simplest solution would be to move the motor as far back into the tender as possible. I will explore that next.
It is still intended to fix the motor with the bath sealant. The bolts in the end are there to resist the torque reaction. If the sealant provides enough "stick" and the bolts transmit noise I can always remove them.
Thanks for your comments
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grovenor-2685
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Re: Contrate and pinion gears

Postby grovenor-2685 » Wed Jun 30, 2021 8:07 pm

hollybeau wrote: In the case of Fig 29 we show how a tender can be close-coupled on one pivot only to the locomotive,

However fig 29 does not actually show that. :) I suspect that the unstated assumptions may be elsewhere in his book, probably where he discusses hanging the tender on the back of the loco for additional adhesion and letting the front two axles of the tender run free.
With a conventional tender guided by its own wheels there will be sideplay between engine and tender on curvature changes and especially on reverse curves and one pivot cannot be used
Regards
Keith
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davebradwell
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Re: Contrate and pinion gears

Postby davebradwell » Thu Jul 01, 2021 8:02 am

Keith sums up the fatal flaw very concisely but I'll go through some stuff to make it clear as this keeps coming up.

Think vertically first. If tender and loco had no suspension and motor mounted rigidly I could be persuaded that with great care in alignment then you could get the coupling halves to line up. I'll also let you stretch this to compensated locos where the rigid axles are adjacent on engine and tender, but this gets a "hmmmm!" If we go to springing then it's hopeless as there's no stable datum and even if you did get the coupling to align, when you put the tender body on, the tender springs will compress further and tender will be held up by the coupling which will take up any clearance in it.

Horizontally, what do you align? There's clearance between wheels and rail, endfloat on axles and some movement on the gearbox - tell me how you get the coupling set so that lot is in the centre to give equal clearance each side. The clearance I've described is needed to make the model stay on the track on curves not allow for misalignment of drive. Further, when each chassis goes round a curve, it is trying to go in a straight line so leading wheel grinds against outside rail and it's evident that there is a different theoretical position for the coupling whether you are going forwards or back. Anyone who has tried to fit cab doors will understand the amount of movement between engine and tender.

Standing back, loco and tender are separate vehicles which will require to move with respect to each other - they can't do this when there is a rigid location - the ball joint - between them. Keith points out that Mike Sharman, in his thorough understanding of the basic principles, would have had some other link between engine and tender and have dealt with the tender wheels differently. He preferred compensation which was pretty standard in those pioneering days but his proposal would still require careful alignment.

If you use 2 couplings all the alignment issues just disappear, as I think you've realised. The gearbox goes somewhere over here, preferably with a little vertical tab bearing on a fixed frame to prevent it going round the axle, the motor goes over there with the shafts sort of in-line as judged by eye and the drive link installed between. Both vehicles are free to move as they wish, can be ballasted as required and it's a doddle with no setting up. Cardan shaft can be very short if required.

You seem to have lost your outside springs which you were relying on to cope with larger than normal torque reaction. They just need 2mm wide slots for the standard bearings which can be mounted in little plates with springs soldered on top - these can rest under spring hanger pivots. Motor might be mounted on a curved saddle with double sided tape or sticky pads.

Must say I'm not over optimistic about the use of such a low final drive gear ratio and a contrate gear isn't great. It will run light but the test will be with it stuffed full of lead and put up against the buffers with wheels spinning.

DaveB

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Re: Contrate and pinion gears

Postby Stephan.wintner » Thu Jul 01, 2021 4:41 pm

I think the key part of Mike's text is " a tender can be close-coupled on one pivot only to the locomotive," which is to say, rather than 2 pivots in the drawbar, just one.

Drivetrain aside, that strikes me as difficult - making the chassis flexible enough, especially torsionally. I can't see how a single universal could work, so I'd be curious how Mike arranged things.

Stephan

bécasse
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Re: Contrate and pinion gears

Postby bécasse » Thu Jul 01, 2021 7:11 pm

Those of us who knew Mike well will remember a very practical man who was unlikely to suggest anything that he hadn't tried successfully, especially if the theory (as perfectly outlined by Dave B) suggests problems.

My inspired guess would be that Mike's personal set up placed the ball joint precisely and closely under the coupling centre pivot and that the slot in tube (which he shows withdrawn back into the tender) was sufficiently long and sloppy to offer adequate flexibility. I suspect that the model concerned would have been one of Mike's "old timers" (and quite possibly a single-driver) and if it was I have seen it working.

However, the fact that Mike could get it to work isn't a good reason to copy his work when a better (double-joint) arrangement is readily available and should work reliably without relying on luck and a prayer. A double-joint system is best set up with one of the joints semi-captive otherwise you can have great fun(?) trying to get both ball joints and the tender-loco coupling together at the same time.

It may be worth having a look at what 2FS modellers do as they are significant users of tender-loco drives and there is a useful 2FS forum on RMweb.

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Re: Contrate and pinion gears

Postby davebradwell » Thu Jul 01, 2021 8:24 pm

All but the rear tender axles would need sideplay with Mike's arrangement but it would still need careful work to get the drive aligned. He knew what he was doing and possibly didn't have space for a second universal. Don't forget the much cursed fall plate and sometimes even cab doors to connect when attaching tender.

Good suggestion to look at what the 2mm folk are doing. I'm floundering a bit after my stash of Dynadrive universals ran out late last year.

DaveB

bécasse
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Re: Contrate and pinion gears

Postby bécasse » Thu Jul 01, 2021 9:04 pm

This youtube video https://www.youtube.com/watch?v=pquYCNKQy70 shows some of Mike's locos that used his single joint system working - and working well!

As I implied above though, just because he could make it work isn't a good reason to copy him.

hollybeau
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Re: Contrate and pinion gears

Postby hollybeau » Thu Jul 01, 2021 9:20 pm

Thank you all for your comments and particularly to Dave for his most thorough and detailed explanation of the problem. This project for me has always been an opportunity to experiment and I am happy and grateful to receive your helpful advice. As a consequence I have reconfigured matters:

20210701_161056.jpg


The cradle and therefore the motor have been pushed backwards as far as possible in the tender. Another rummage in the parts bin revealed a double ended set of universal joints and connecting shaft bought years ago from Branchlines. It is made of some sort of hard plastic. I am not sure of its durability but it should be quiet and it would be easy to replace if it fails (just tight push on at both ends). There is a splined connecting cardan shaft between the fore and aft sets which is not obvious from the photo. Looks as if this will do the job. This should resolve the issue raised by becasse about assembly.
Because the shaft runs just under the footplate of both loco and tender there is no room to place the drawbar in its conventional location. The latest experiment is to run two u-shaped "stirrups" dropping below the drive shaft onto which I can hopefully attach some sort of draw bar. This will be pivoted at both ends. This will not win any beauty competition but the whole contraption is hidden behind the steps on both loco and tender. The stirrup on the loco end is soldered to double-sided copper paxolin strips to avoid shorting out the split chassis.
To answer other questions I have gone with the inner chassis as the pin-points/sprung axleguards suited a metal tender : the plastic Bachmann tender virtually ruled that out. In addition it was not obvious to me how I could sling a motor into that lot without cutting through the horizontal stretcher of the axleguard assembly. I think I will stick with the hornblocks I am using. I have used these successfully before.
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Horsetan
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Re: Contrate and pinion gears

Postby Horsetan » Tue Aug 31, 2021 3:14 pm

I recently stumbled across a DCC wiring project and discovered that Piko (in its former East German era) did design and equip their DB Br. 66 2-6-4T models with a contrate-and-pinion drivetrain. The mechanism looks adaptable and ripe for a coreless motor and maybe a flywheel as well.

Overhead view of BR.66 chassis on these pages here

I seem to recall Jouef (before takeover by Hornby) also employed contrate-and-pinion in some of their models as well, so it's not exactly an unknown system in the RTR world.
That would be an ecumenical matter.


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