Scratchbuilding a tender drive

[hayfield]

Sometimes we can over engineer solutions, I have one of these units where a round can motor has been used, butis very simple and effective solution. Sorry for the poor link for the MRRC slimline motor bogie drive first photo

 

https://www.google.co.uk/search?q=OO+Gauge+Airfix+MRRC+Slimline+Electric+Motor+%26+Mount+L63&biw=1280&bih=894&site=webhp&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjugcyjkJbQAhXFuhQKHSxUALwQsAQIGg&dpr=1

 

Those who are good at drawing up etched brass designs may be able to do something similar, or perhaps using a Comet Models tender chassis duly modified.

 

Most of my items are packed up in the loft, I may struggle to find my example

[chris p bacon]

Many thanks for the ideas so far, even if I can't use them this time I have a few others where the tender might be the better option.

 

I did look at trying to drive the trailing wheel as well, the problem I came up against was my own understanding of gears/ratios and how it could be done, The Driver is 7'6" and needs a high (numbered) gear ratio or else the motor won't be able to start it, the trailing wheel is 4' and there is 34mm between axle centres meaning quite a long gear train, this has to be coupled to a large gearbox on the driver and the motor and there is just physically so little room to do it. I would if possible like to keep the cab open as JC went to the trouble of putting backhead detail in. 

One other issue is that the chassis is printed in WSF which has a small amount of flexibility, so should I want to try and drive both the drivers and trailing axle I think I would have to do the frames in brass.

 

Waiting for bits from the postie.

[hayfield]

Found it, I have no idea if the gap for the motor has been enlarged as a Sagami motor has been used, also being round rather than a flat can obscured the middle axle. Looks to be about 1 mm thick sheet

 

 

The wheelbase is 52 mm though there is a hole either side about 4 mm apart making a max 60 mm spread

 

 

Length of the chassis 82 mm

Height 22 mm

Depth  11.5 mm

 

 

Hole for motor 31 mm x 12 mm, though these could have been altered

 

Hope this may be food for thought, or may push someone into making a tender drive unit

 

[chris p bacon]

Thanks John, that looks suitably simple. I've sketched out a few of the ideas but keep coming back to this sort of thing, it's mainly due to the lack of space when the gearbox and motor are fitted, as along with all that there is a chip required.

[hayfield]

Chris I mad a simple Bo Bo motor bogie for a MTK diesel loco with 1/8th brass bars (a-la K's) with a motor which had a double ended shaft with Romford gears on each end. The motor was held in place with Milliput. I think a couple of decent motor mounts/gearboxes would be much smother, if using a couple of Highlevel boxes you could attach the motor to one and use the shaft bearings both sides of the gearbox. Just need a flat can motor and a box which keeps the motor above the centre axle 

[relaxinghobby]

One I prepared earlier...

 

Here's my Stirling single 2-2-2 so far a failed project or just resting?

 

It started with a side elevation drawing and a damage Airfix kit with cylinders missing, I noticed that the rear end of the kit fitted the drawing, these two prototypes must have used the same boiler, cab, etc. The big splashers and all other mods are plasticard creations.

 

For the crucial look of these engines the splashers must be made to look very neat.

 

The first version had a plasticard chassis and was a push along model with an American diesel chassis disguised as a coach hidden in the train. It worked and could be used for other occasionally run motorless models just to watch them run by but, no shunting. The second attempt was to motorise the chassis using a metal block from a Triang Caledonian/GWR single. I've got a two stage Branchlines slim gearbox there but stuffing it all inside the body shell stumped me, a slimmer motor might work. Maybe.

Third attempt was to put a Bullant motor unit with 16 mm wheels inside the skinny tender shell, It just fits, but there is not enough room for much ballast weight in this tiny tender body.

The problem here is that the Bullant is too slow, ideal for a goods loco so this tender now powers a slow mineral 0-6-0.

 

Summary

1 No motor at all, use motorised coach hidden in the train to do the work.

2 Proper drive to the big single driving wheels, but there is only a small space in the prototype.

3 Motor bogie hidden in the tender.

4 Motor in the tender with a drive shaft to a gearbox on the driven axle. Mechanically too sophisticated for me.

 

PS I've just remembered I once saw a P4 4mm model of a Stirling single 4-2-2 where the builder drove the trailing wheel through a two stage gear box that put the motor up in the boiler, still a single but not as we normally think of it.

[chris p bacon]

So I'm not the only one then   and you also found  there really isn't a lot of room in the boiler.

 

I like the Bullant and could order one but I fancy messing about and making something, I'm guessing that as you chopped a Kitmaster Single about and used the tender with the kit you probably didn't realise that it was the tender it gained in preservation and was actually a Sturrock tender whereas No1 actually had a larger tender when in service, as I'm using the larger tender for the B3 I should gain just that bit more room to add some weight which you weren't able to.

[DCB]

 

Summary

1 No motor at all, use motorised coach hidden in the train to do the work.

2 Proper drive to the big single driving wheels, but there is only a small space in the prototype.

3 Motor bogie hidden in the tender.

4 Motor in the tender with a drive shaft to a gearbox on the driven axle. Mechanically too sophisticated for me.

 

PS I've just remembered I once saw a P4 4mm model of a Stirling single 4-2-2 where the builder drove the trailing wheel through a two stage gear box that put the motor up in the boiler, still a single but not as we normally think of it.

 

You missed one option. Powered tender plus drive to the loco wheels.   I saw several dual powered Hornby locos in Cheltenham Model Centre many years ago, Hornby Black 5s etc with an X04 for loco drive plus powered tender.

 Thinking laterally I assume the singles had quite deep ashpans so there should be room for an N gauge loco motor in there, and there is no law which says the worm in a worm drive has to be above the worm wheel so you could use a small diameter worm wheel, Romford 40:1 ? and hide the motor between thin brass or plastic card ashpan sides.

Powering those big driving wheels and adjusting weights so the tender pulls the train but the loco wheels slip before the Tender could be interesting, as could making the drivers slip backwards while stopping as I assume they had no loco brakes?  Just tender?   I have some Triang Lord of the Isles wheels in my scrap box, I feel an experiment coming on.

[JCL]

Of course Dave, th e easy way would be to use it on a double header which was common later on

[relaxinghobby]

A cheap way of getting a tender drive, use an old diesel loco motor bogie.

 

157

 

158

Just a plastic box at this stage, a bit bigger, a bit more room for ballast weight than the skinny Airfix one. This has been languishing in a margarine tub storage unit for years. The frames are there next to it. The dimensions are based on the proper larger tenders the Stirling locos were paired with.

 

 

160

I don't know what make this motor bogie is, I chose it because it has metal flanges on all wheels and

in the second hand stall scrum I did not notice it had an uneven wheel base, that could hopefully be hidden behind the frames.

 

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162

 

163

For a really big tender with lots of room to hide a really massive and powerful motor you could use a LNER pacific tender, this is a Hornby one. I took the metal wheels from it as they are the same size as the singles carrying ones, 16 mm.

[chris p bacon]

I've made up the tender drive and posted it in my layout topic. (post #388)

 

http://www.rmweb.co.uk/community/index.php?/topic/57208-sandy-gn-lnwr-or-bre/page-16?&p=2494733

[relaxinghobby]

 

I've found the components of a failed tender drive  construction attempt in the margarine tub of doom.

It did not work, a U shaped channel holds together at each end two Highlevel gearboxes.

 

I think that's an old fashioned DS10 motor, the shaft sticks out of both ends and there is room for a flywheel too.

 

The idler gear axels hold the parts together, an idea I borrowed from HIghlevel's own design of replacement Hornby ex L&YR pug.

 

My home made parts just were not up to the job so this shebang never worked.

[chris p bacon]

If you look at my layout thread (bottom) I got mine to work and work well, using a Mashima I fixed a High Level Roadrunner compact+ gearbox in the normal way to one end and made up a fixing for the other end for a second gearbox. Seems to have a good bit of traction and speed, also managing to get plenty of lead in the tender too.

 

Here's a piccie with more in my thread.

[hayfield]

Dave

 

Top marks for a super bit of modelling, how about getting a set of Gibson tender mainframes and hornblocks and make a sprung version 

 

Seriously though Alan Gibson will supply the mainframes with axle bush holes rather than slots for hornblocks, which may assist those who do not fancy making the mainframes

[chris p bacon]

Dave

 

Top marks for a super bit of modelling, how about getting a set of Gibson tender mainframes and hornblocks and make a sprung version 

 

Seriously though Alan Gibson will supply the mainframes with axle bush holes rather than slots for hornblocks, which may assist those who do not fancy making the mainframes

I never thought of that so I'll investigate as I've at least one more to make,  possibly 2. I do have quite a bit of scrap/offcuts of brass strip so the temptation is to use that.

 

Next time I will cut some brass rod/square and drill and tap to make the spacers, would have been much easier. 

[gr.king]

I'm VERY late in adding my thoughts to this, but as well as the possibility of ignoring the driving wheel and driving the carrying wheels of the loco instead, giving good balance and grip but poor realism if you like wheel slip, there's another idea:

If you don't mind making up simple gear mounts of your own,  I believe the driving wheels and the trailing wheel can be driven off one motor, as in my "4-6-0" Atlantic. The cheap nylon gears sold by Squires for instance include a 30 and a 16 tooth version, suited to coupling a 7'6" driver and a 4' 0" carrying wheel, though you can get away with a slight mismatch in the ratios and diameters. And before the engineering theorists howl about friction, O YES YOU CAN, I've done it!

I think you could gear couple the wheels, with the motor driving the proper ones and mounted forward in the boiler, leaving the firebox free for weight to be added. In order to get the biggest possible motor in and out of the boiler without a cut-away boiler bottom, it looks to me as if the loco outline is so simple that the entire boiler could be a separate piece, sliding in from the front between the splashers and sandboxes and plugging into the cab front, then being held by a screw in the base of the smokebox.

Looking at that gearbox already in the powered 2-2-2 chassis, I'm even wondering if you could use the gear in the "heel" of the gearbox as the first in a train of gears leading to the rear axle. It depends on what the gears are and what you can get.....

[chris p bacon]

I did sketch out the possibility of driving the 7'6" driver and the 3'11" trailing wheels but I just couldn't figure out the ratios required, I think that I was being a bit too precise and worrying about a mismatch.

The tender drive has worked out well for this one, it has a decent turn of speed and power.   I do intend having another B3 and for that one I might well make up my own chassis out of brass and incorporate the gear train and its carrier shafts within it as I do like a challenge. I did try a few motors I had and it does need one with enough power to spin that driver and haul some weight without stalling hence why the motor eats the available space.

The loco body itself is a 3D print by JCL and comes as one piece, I don't know how easy it is to split the design up into seperate components and also how that could affect the print. The underside is open and fully accessible, there just isn't much room.

 

I must revisit your 4-6-0 Atlantic for a bit of inspiration.

[JCL]

The loco body itself is a 3D print by JCL and comes as one piece, I don't know how easy it is to split the design up into seperate components and also how that could affect the print

 

It wouldn't be difficult, but I don't think I'd do it for you... well at least not before Christmas, we've already bought the Baileys.

[gr.king]

Not essential to redesign surely? A whole one could be split with a fine razor saw......

[JCL]

Nobody is cutting up my bottle of Baileys.

 

...

 

Sorry Graeme.

[gr.king]

Unless standards over the pond have slipped even more than they have in the UK, I believe your Bailey's is still safe by virtue of being in a glass bottle rather than plastic. I could always get the cutting discs out for my mini-drill of course......

[chris p bacon]

Unless standards over the pond have slipped even more than they have in the UK, I believe your Bailey's is still safe by virtue of being in a glass bottle rather than plastic. I could always get the cutting discs out for my mini-drill of course......

The presumption is that they have standards...

 

Hat 

 

Coat

 

Yeeeee Haaaaa

[chris p bacon]

  I believe the driving wheels and the trailing wheel can be driven off one motor, as in my "4-6-0" Atlantic. The cheap nylon gears sold by Squires for instance include a 30 and a 16 tooth version, suited to coupling a 7'6" driver and a 4' 0" carrying wheel, though you can get away with a slight mismatch in the ratios and diameters. And before the engineering theorists howl about friction, O YES YOU CAN, I've done it!

 

I found the article, very interesting and like how you've achieved it, using the 2nd axle driven by the rods to power the gear train to the trailing wheel. It's in the memory bank for the future and I shall see what I can come up with, I've got stacks of brass gears and if I was able to use those they add weight. 

I'm working on a pair of A5's (4-2-2) but with those there is a little bit more room for weight with a High Level gearbox and motor.