7mm Steph's 'Western' - real workbench...

[Steph Dale]

Or perhaps 'Western Brainpop'.

It seems reasonably common knowledge that I've got one of the JLTRT kits of the Western; more because it's a cracking kit from which I've seen some lovely models and I'm a big fan of Stroudley's Improved Engine Green, than for any love of the prototype. To be honest mention the words diesel-hydraulic to me and I tend to think of DB's V200, SP's lunatic KMs or even the spectacularly unreliable Romanian-built East German BR119 rather than anything that ran in this country.

But I do admire a bit of class; the styling of the 52 is a ruddy marvel and they sound right (if not quite in the same league as a Deltic or supercharged Alco 251).

There are many solutions for driving them with off the shelf options from ABC (in two forms), DJH and Slater's, good kit versions from Roxey and there's even the ones I do. So, bearing in mind the latter were developed with a completely different approach in mind, would they work and fit? How?

Trying to work it out seemed very possible and the sketches in my log book showed that there was a solution (well actually several solutions) but I couldn't quite visualise it. So before committing to anything I broke out TurboCAD and decided to have a little look-see. And yes - I'll be happy to do this for any prospective user of the wee beasties.

Pics and prose shortly...

Steph

 

[Steph Dale]

I started off with the kit parts in front of me together with suitable measuring implements, which meant I could get the kit parts 'assembled' on the drawing board, which looked a little like this:

This shows the major components in simple outline, including the bogie frame (red), chassis (brown), assembled bogie mounting fret (green), bearings (magenta) and wheels/rail (black). If I drop down to the bogie and chassis you can see the motor cut-out aligns with a similar cut out in the chassis.

This is, of course, absolutely wonderful for a vertical-mounted motor and Delrin drive, whichever gearbox you use. Although I could have used one of my gearboxes with Delrin chain, what I actually wanted to do was this:

No real clearance problems were apparent, although it was becoming obvious that a chunk of the bogie frame would have to be cut back. The questions was then whether anything else would need work:

First thoughts were to use a Mashima 1824 and this is indeed possible. In fact, it's remarkable how little jiggery-pokery is required with the motor mounted in this fashion - it's clear of the bogie mounting and even fits (just) in the chassis cut-out so only a little fiddling would be required here. Working out the bogie frame cutting got me to something like this, the hatching showing the areas to be removed:

Even this isn't a show-stopper, there are a couple of simple ways the bogie frame can be strengthened to make up for the material removed, so no concerns here. Wonder how a larger motor would fit? Well, the Canon or Mashima 1833 was no chance, the motor case overlapped with the centre axle, but what about the Mashima 1830 (actually 31mm long!):

Hmm, no change there then. How does that affect the rest of the components?

Not too badly actually; there's a need to remove some material from the chassis, but it's well-reinforced with two thick beams either side of the bogie mounting (not shown in my drawing) and the bogie mounting needs trimming to clear the back of the motor, but there's plenty of material left so I can't see a huge problem. We may well have a solution...

Steph

 

[mickoo]

Isn't the appliance of science wonderful LOL

 

[Steph Dale]

Just thought a quick follow-up to show a vertically-mounted motor still fits - I've stuck with the 1830 template, just rotated/reflected it:

 

[Dog Star]

Steph, I like your thinking. How does your motor / gearbox combination compare with an ABC diesel motor gearbox (using a Maxxon 6w and geared for 80mph) in regards to (a) performance and (b) price?

For what it is worth, the motor space in the bogie casting appears to be machined rather than cast... or there is more than one pattern /mould. We have two Wizzos here and the bogies have three sets of dimensions for the cut-out!

regards, Graham

 

[SteveO]

Looks interesting – not for the prototype, but for Steph's gearboxes, which I'm quite interested in for all of my non-shunter locos.

 

[Steph Dale]

Steph, I like your thinking. How does your motor / gearbox combination compare with an ABC diesel motor gearbox (using a Maxxon 6w and geared for 80mph) in regards to (a) performance and (b) price?

For what it is worth, the motor space in the bogie casting appears to be machined rather than cast... or there is more than one pattern /mould. We have two Wizzos here and the bogies have three sets of dimensions for the cut-out!

regards, Graham

Hi Graham,

On performance it's quite naturally down on power, but having seen and heard what locos running with two Mashima 1833s can do I'm sure I'll be very happy with the performance of this loco. The 1830 is often overlooked but it's a real peach of a power unit that I've used for many years in HO stuff. For your comparison (Branchlines figures):
Mashima 1830 10500rpm no load, 3.6w@5000rpm peak power
Mashima 1833 9400rpm no load, 3.1w@5000rpm peak power
Mashima 1824 11000rpm no load, 1.8w@5000rpm peak power
Canon 1833 10800rpm no load, 4.5w@5500rpm peak power
I've looked up the spec for the Maxon 202413 (which ABC list as their '6w');
Maxon 202413 10400rpm no load, 5w@7770rpm peak power
Of course, if you're using only the one ABC motor bogie then the comparison is much more even - I'll actually have a little more power and greater adhesion (7.2w over four axles rather than 5w over two axles). What's interesting is that the max power is higher up the rev range of your motor - coreless motors have flatter torque curves than conventional motors so I suspect the overall performance (haulage, speed) of the two drives is pretty similar on the track.

Using any of the motors in that list will happily give you running to 80mph assuming sensible efficiency; the gears I use are pretty good and the ballraces count for a great deal - the gearsets can be back-driven with care. They're also exceedingly quiet if assembled accurately (which is highly likely if you follow the instructions!). Unlike ABC I'm stuck with only one ratio (13:1), so the motor selection can be a limit on absolute maximum speed/power. I hope that's answered some of your question on performance, but without an ABC unit to do an A-B comparison it's a bit tricky and somewhat subjective to answer. I also guess it depends on your performance measures!

Price? Well the gearboxes and drive shafts work out roughly £50 to drive two axles of a bogie, so you need to add around £20-25 for your motor, plus £41.37 for three axles of Slater's wheels for a sensible comparison. Total would therefore be around £117, which doesn't compare too badly with ABC's £210 (for the full drive bogie) or £161 (motor, gearbox, Delrin chain drive, wheels) for the specification you quote.

To be fair, these drives weren't developed to take on ABC; where the SDMP drives score is their compactness, allowing the drive to be contained in a bogie, which is also useful if you're trying to engineer them in to a completed model. They can also be used with a variety of springing/compensation systems (such as the MMP application they were originally designed for) and even in rigid bogies. They happily work with split axles and would even solve your dual-gauge (FS and S7) problem! Of course, for a JLTRT Western such as this, the real opportunity would be to mill out part of the fuel tank and stick the motor(s) in there, driving out to the bogie on cardan shafts, much as the prototype does, this too is entirely feasible with the SDMP 'boxes.

Thanks for the detail on the motor cut out in the bogie frame. I was convinced that the marks on the cut out were indicative of milling, so can't say it's a major surprise. I guess it's a 'tweak' to allow their new Slater's-based drive units to fit easily.

Steph

p.s. If anyone objects to the 'sales' aspects of this post I'll be happy to remove the relevant parts; as you can probably tell, I'm enormously proud of the drive system and very pleased to see it can be applied outside it's original design brief.

 

[JimG]

Not too badly actually; there's a need to remove some material from the chassis, but it's well-reinforced with two thick beams either side of the bogie mounting (not shown in my drawing) and the bogie mounting needs trimming to clear the back of the motor, but there's plenty of material left so I can't see a huge problem. We may well have a solution...

Steph,

What happens if both driven axles are sprung. I can see that the motor can be axle hung on the inner axle via the gearbox and the shaft to the other gearbox would also effectively be a torque arm. If the axles are sprung is there a possibility of torque reaction causing varying loads on wheels?

I've actually been thinking about doing something similar in an American outline S scale diesel - replacing existing American Models power bogies with bogies carrying UK S scale standard wheels and springing the axles. I will still use the existing centrally placed motor and cardan shaft drives in the loco and have a spur gearbox, in place of your motor, driven by the cardan shafts.

Jim.

 

[Steph Dale]

Jim,

Depends how you do the springing and how much weight you have on the loco. I did a quick check through for use of conventional sprung hornblocks and there isn't much in it - the gears and ballraces are efficient enough that the whole lot can settle against the stops on level track. I'm still looking at other solutions, but seeing the 4mm boys get away with it in a much smaller scale I'm not currently anticipating any problems. It's also worth adding that the location/positioning of the torque reaction arm can help mitigate any 'funnies' if they emerge (e.g. having the torque arm cross over the input shaft).

The JLTRT kits come with rigid bogies, although they do make allowance for the centre axle to ride up and down (no downforce spring is provided and no clearance for sideplay either!).

I haven't illustrated any of the torque reaction links yet, the arm sticking out of the gearbox actually represents the cardan shaft's 'clearance volume'. In practice I'll solder a length of 0.7mm brass wire to the 'free' gearbox and anchor it in the frame somewhere, much as I did with my Class 47 (see Post #48). For the motor end there'll be a frame strengthening pin judiciously sited under the tail end of the motor to act as a torque arm - running a length of flexi wire over the rear boss of the motor to secure to the strengthening pin will secure it in the opposite direction.

I suspect we may well return to the question of suspension/springing...

Steph

 

[Overseer]

Steph,
When I started reading the first post I was expecting you to develop a prototypical arrangement with a central gearbox driving all the axles through prop shafts to axle mounted gearboxes. A large motor would take the place of the diesel engine. Then you could model the strange torsion (?) arms in the bogies and have the model hunker down when starting a heavy train as the prototype apparently did. Might be a bit more complex to get it all working though. I have been thinking about powering a Hymek in a similar way using a large ex military surplus coreless motor I have lying around, but it is a low priority.

 

[JimG]

I haven't illustrated any of the torque reaction links yet, the arm sticking out of the gearbox actually represents the cardan shaft's 'clearance volume'. In practice I'll solder a length of 0.7mm brass wire to the 'free' gearbox and anchor it in the frame somewhere, much as I did with my Class 47 (see Post #48). For the motor end there'll be a frame strengthening pin judiciously sited under the tail end of the motor to act as a torque arm - running a length of flexi wire over the rear boss of the motor to secure to the strengthening pin will secure it in the opposite direction.

I suspect we may well return to the question of suspension/springing...

Steph,

Technically the motor shaft should be a torque arm for both gearboxes but under load, would the increased friction on the shaft bearings cause problems. I wonder too, with separate torque arms on the gearboxes, whether there might not be increased load on the shaft bearings in any case with a small amount of play in the torque arm bearings.

Jim.

 

[Dog Star]

Steph, thank you for the analysis and comparison of your products versus the ABC approach - I do not object to the "Sales" patter in this thread for, after all, you have every right to be proud of what you have achieved.

If you use ball bearings for the gearbox and split axles for the power collection, how do you ensure that there is no arcing/pitting within the ball races?

I like Fraser's idea of a transmission which mirrors the prototype, a model Wizzo which sits before take-off sounds just right... a germ of an idea which might blossom in Bristol?

regards, Graham

 

[ZiderHead]

... it would enable the use of a much larger single motor too - more efficient, more torque and lower rpms meaning less gearbox losses and noise, and lower unsprung mass for simpler more efficient springing. all round advantages.

It also presents options for where the gearing is located - with the motor in the body vs in the final drive. you would also have the option to fit a small hydraulic coupling for prototypical motor (engine)/loco starting speed

 

[lancer1027]

Im very interested in your work here Steph
As from our conversation at Telford.

Rob

 

[Steph Dale]

Steph,
When I started reading the first post I was expecting you to develop a prototypical arrangement with a central gearbox driving all the axles through prop shafts to axle mounted gearboxes. A large motor would take the place of the diesel engine. Then you could model the strange torsion (?) arms in the bogies and have the model hunker down when starting a heavy train as the prototype apparently did. Might be a bit more complex to get it all working though. I have been thinking about powering a Hymek in a similar way using a large ex military surplus coreless motor I have lying around, but it is a low priority.

Fraser,
It's entirely possible, but in this instance I got concerned about the loss of efficiency in having what are effectively redundant gearboxes; there's enough space to mount it all in the bogie cutting out at least one u/j set and the spur gearbox. The reaction arms seem to be pretty conventional when looking at the prototype drawings, with the only 'funnies' being the ones to impart a centre of rotation to the bolsterless bogie - these being removed pretty early on.
I guess that if I had found some very efficient spur drive boxes that didn't cost the earth I might have given it a whirl, but in the end I feel it's just an un-necessary complication.

Steph,

Technically the motor shaft should be a torque arm for both gearboxes but under load, would the increased friction on the shaft bearings cause problems. I wonder too, with separate torque arms on the gearboxes, whether there might not be increased load on the shaft bearings in any case with a small amount of play in the torque arm bearings.

Jim.

Jim,
Not to sure about the 'should' (which tends to indicate a desirable condition or outcome) but yes; the motor's own shaft could be used for torque reaction. I'm not convinced the motor manufacturer would encourage a bending moment of that sort along the shaft though! There's also the small matter of any lateral movement on the gearboxes, so building them around a common shaft isn't such a great idea. I'm much, much happier treating the 'boxes separately and then linking them with the universal joints. As an aside it also allows the reaction arms to be long and therefore allow the gearboxes as much freedom as required to move in helpful directions.

Steph, thank you for the analysis and comparison of your products versus the ABC approach - I do not object to the "Sales" patter in this thread for, after all, you have every right to be proud of what you have achieved.

If you use ball bearings for the gearbox and split axles for the power collection, how do you ensure that there is no arcing/pitting within the ball races?

I like Fraser's idea of a transmission which mirrors the prototype, a model Wizzo which sits before take-off sounds just right... a germ of an idea which might blossom in Bristol?

regards, Graham

Graham,
The gearboxes are asymmetric, so the split goes to one side of the gearbox and there's no power going across the bearings at all. That asymmetric location and length of exposed axle could also be used for an axle pin were you to take up Col's (Eastsidepilot) suggestion for your dual-gauge Western.
A suitable location for the split or pin is marked on the axles and can be seen in the first drawing as a line across the axle, off-set on the driven axles and in the centre of the un-driven axle.

... it would enable the use of a much larger single motor too - more efficient, more torque and lower rpms meaning less gearbox losses and noise, and lower unsprung mass for simpler more efficient springing. all round advantages.

It also presents options for where the gearing is located - with the motor in the body vs in the final drive. you would also have the option to fit a small hydraulic coupling for prototypical motor (engine)/loco starting speed

Jon,
You're quite correct on the motor speed vs. noise issue - in this case with 13:1 gears you'd end up with a slow-running loco if you used a low-revving motor. The approach you quote is entirely valid if you could find a sensible, affordable, cost-effective range of compatible motors and gears.
Your comment on the reduced unsprung mass is valid for the gearboxes I do - it all depends how you fit them; something I expect to be exploring in this thread. The reduction in unsprung mass is desirable to reduce rail noise, particularly any clatter that might be associated with poor track.

Im very interested in your work here Steph
As from our conversation at Telford.

Rob

Rob,
I well remember; although you weren't the only person to talk to me about drive for the Western. I think you're looking at garden railway use with R/C? In that case the only suggested change I could make to you would be to consider the use of ball-races for (some of) the axles of your loco. Without pick-ups to worry about you'd really see the benefit of the ball race approach.
Steph

 

[lancer1027]

Ok Steph, that sound a good idea. Yes your correct i am looking at R/C

I will watch this thread with interest and start saving

Rob

 

[lancer1027]

Also Steph, im watching this space for the arrival of a 8' 6" DMU type bogie with the motor really low as not to use up much of the parcels bit on the body. ( this space i need for batteries for R/C )

Rob

 

[Ressaldar]

Also Steph, im watching this space for the arrival of a 8' 6" DMU type bogie with the motor really low as not to use up much of the parcels bit on the body. ( this space i need for batteries for R/C )Rob

me too, but mine would be for Route Learner/Sandite units

cheers

Mike

 

[Steph Dale]

I have been 'playing' with this off and on since my last post. Other ideas have forced their way into my head than just the motorising; could the bogies be made up sprung or compensated and could worthwhile secondary suspension be provided, primarily as a way of overcoming the 'one fixed, one rocking' bogie arrangement normally employed...

There are an awful lot of different approaches to springing and compensation, but one that most intrigued me was the use of CSBs which seemed to give the best of both the compensation and springing worlds. But there's some 'interesting' advice on the CLAG pages associated with CSBs and their use in diesel bogies so there I let it rest. And then I realised that although the bogie wheelbase of the Western is pretty short, the overall frame length is actually pretty useful. A lunchtime mucking about with the MSExcel downloads and I had a solution that seemed to work, but I still wasn't sure I'd have either the width or height to get it in and allow the bearings to move up and down. Worth a try...:


The CSB system is actually in green and consists of piano/guitar wire of roughly 0.61mm dia. Most of the fixings to the frames can be achieved using the now-standard 4mm scale approach of using Markits WD handrail knobs. The only exception is that two are built in to the spacer that stiffens up the bogie frame - the vertical green lines in the drawing. Incidentally, not shown here is the trick for stopping the bearings spinning round in the frame, we'll get to that in due course.

And so to the next evolution - the secondary suspension. This gets a little more interesting - to start with it's only treated as 'two-axle' case; there are two loading points. And the other thing is that the weight loaded is only that of the body - the entire weight of the bogie is below the springs and forms no part of the issue here. In this loco there were issues with the springs extending under the cab floor (dotted brown line) which was going to mean filing some material out, but nothing major. What I decided to do was set 1.5mm diameter pins out of the top of the bogie frame. The tops of these will run in 1.5mm id 'U' channel, with the springs loading the tops of the channels:

You can also see that the frame top strengthening ribs have made an appearance on the drawings as I needed to work out how much space I actually had for the secondary suspension to fit.

Well, that's as far as we have it at the moment. Parts have been ordered and hopefully I can make a start on this shortly.

Should be fun.

Steph

 

[Steph Dale]

And so work begins. Got the wheels in the post this morning so I was able to make a start.

First job of the day was to fill the redundant holes in the frames. Rough shapes were cut from 0.080" styrene sheet so that they just grab the holes. Once in place super-runny superglue is dropped on to fix the styrene plugs, before tissuing away the excess. A short while later a thicker superglue was used as a filler with accelerator applied, before rubbing down with 150grit emery paper. Job done. Then it was time to open up the bearing holes in the frames so that the bearings would fit - dry run at the moment. I also made up a set of gearboxes, in this case the 'Power' was made up on to an 1824 so I could see how well it fitted:


It was then time to look at improving the clearances for the transmissions itself; time to print off the diagram and do a compare/contrast:


I was comfortable that the transmission would fit, so thought I'd better quickly put a set of wheels in the bogie to see whether they were square or not. It's still all unfixed at this stage, but it confirmed that the bogies are square. If I'm honest it was a bit of a surprise:


Pitching dimensions off the drawing with dividers marked out the shape required for removal. Using a 5mm drill, coarse piercing saw and 6" round and flat files soon got the shapes out:


And then time for a quick test installation of the motor and gearboxes. Don't worry too much about the drill through the bogie mounting holes - it's just a convenient way of supporting the back of the motor at this stage:


Clearance around the 'Remote' gearbox is pretty good:


But the clearance around the 'Power' needs a little adjusting:


Like this, I think. The increased cut-out is on the frame on the right. I'll make sure the drawings are corrected, just in case anybody needs a copy.


At this stage I'm pleasantly surprised by the residual strength in the bogie although it does warp perhaps a little too easily. I guess that for some people just screwing the bogie mounting in place would be enough. However, it's not too difficult to get a lot of the strength back in to the frame, which I'll come to next. Once I've got delivery number 2 here...

Steph