Small and Whacky

[daifly]

Provoked by Simon's comment in the 40HP Simplex thread, I thought that now would be a good time to join in!
Whilst chatting to Derek Mundy at Telford in 2011, I was admiring not just the semaphore signals that he was making but also some of the locomotives that he had built which were also on display. Among them was a diminutive and unusual Greenwood & Batley 4wBE (4-wheel battery electric) locomotive. This is the loco that the kit replicates:

This is Greenwood and Batley No.2000 (built 1945) in the sidings at Stourport Power Station on 14th April 1974. This locomotive had previously been used at Worcester Power Station.Photograph taken by Andrew Smith

https://flic.kr/p/JDz47h

Derek had designed a basic set of parts to satisfy a client’s needs and was selling off the surplus as basic ‘kits’. My traditional prevarication meant that it was only at the Swindon ‘Steam’ festival a couple of weeks later that I bought his last remaining kit. It is the cheapest 7mm locomotive ‘kit’ that I have ever bought but is far from a complete kit! What I got for £47.50 is a set of etchings for the chassis and body plus cast whitemetal axlebox/springs. Derek has also included several pages of notes with colour photos covering the prototype history and assembly.


This little lot is also needed:


Slater's wheels, industrial buffers (Walsall), 1420 motor and 40:1 gearset, couplings, wheel bearings and a Dick, Kerr-type tram controller from Terry Russell trams - thus more than doubling the initial cost!

It will be DCC-fitted but, being a battery-powered prototype, a sound chip is probably superfluous.
Achieving adequate adhesion with only one powered axle will not be easy but packing under the battery box covers with lots of weight will help. The prototype normally only moved 4 or 5 wagons on the level. Having recently seen a photo of the Delrin drive on one of John Dale’s Ruston 48DS models, I have also added that to the inventory to assist both drive and current collection. I also spoke with kit designer Derek and inspected his completed model, I shall copy him by springing the unpowered axle to assist adhesion and current collection.

A prolonged power cut this afternoon provided a perfect opportunity to mke a start on fettling the frames and body. There is a large number of rivets to be formed and for that I used my GW Models rivetter. In anticipation of needing to use it, a couple of weeks ago I mounted it on a lump of 18mm ply to give it stability and allow it to be clamped if necessary. But where were all of the extra anvils and punches that it came with. Unable to find them, I contacted George Watts and he supplied a complete new set of 5 for £12.50 + £2 p&p.

Power has now been restored and assembly of the body can start. The wheels are with Colin D. being reprofiled to S7.

So why S7?

My erstwhile Aldbourne layout plans have been stalled as I wasn't happy with the balance of the design. I have been tinkering with the plan over the last couple of months but have not really moved forward much. I have found myself increasingly distracted by the several ScaleSeven threads on WT and confess to long having had a desire to build a S7 layout. My original intention had been to build to O-MF standard but, since I will need to build all of my own pointwork anyway and have several locos and wagons still to be built then, on reflection, I might just as well be building everything to S7 standards.

The possibility of a house move in the next 12 months has made me focus on building stock for a new layout. The existing baseboards will remain empty until the final shape and size available in a new house becomes clear.

Spending several days at a stretch working away from home also limits the modelling opportunities so there will not be frequent updates or rapid progress!

Dave

 

[Simon]

I like the look of that, hopefully just the job for a bit of relatively stress free locomotivery.

In the meantime I'm still stuck in ballast-land but will soon need more motive power!

Simon

 

[SteveO]

Cute little loco! Looking forward to seeing it come to life.

 

[adrian]

It will be DCC-fitted but, being a battery-powered prototype, a sound chip is probably superfluous.
Achieving adequate adhesion with only one powered axle will not be easy but packing under the battery box covers with lots of weight will help.

Interesting project although you should fill it with LiPo batteries and radio control for that truly authentic power drive system.

 

[Scale7JB]

S7...!

You know it makes sense..!

JB.

 

[daifly]

Interesting project although you should fill it with LiPo batteries and radio control for that truly authentic power drive system.

Maybe I should - but I won't! The challenge for me will be to build it, get it to run reliably through as-yet unbuilt S7 pointwork and have functioning DCC control. Don't hold your breath - it won't be working at Larkrail although I will!

 

[Steph Dale]

Dave,

That looks a charming kit - I'm just wondering whether a higher gearbox ratio might help with slow running? There are 54:1 gearboxes available which should be roughly the same size as the gearbox you've got; the Romford 54:1 gear is about the same size as the Markits 40:1.

I'm sure (Yorkshire) Dave will be along soon too; he has a predilection for old electric locos...

Steph

 

[daifly]

Thanks for that, Steph - I'll bear it in mind. My usual technique is to misalign the wheel bearings, overtension the Delrin and use the pickups as brakes. It's often a miracle if the thing moves at all!

Dave

 

[Steph Dale]

In that case, and with your unfortunately low level of expectation, I'm sure you'll be fine

Steph

 

[Yorkshire Dave]

Interesting little kit and I'll be following the build.

Could the drive mechanism be made up as a drive bogie with one axle being able to rock slightly to assist adhesion or is the wheelbase too short? In respect of the pickup problem and you're using DCC, you could install a 'keep alive' capacitor in addition to the decoder to help overcome this.

I'm just waiting for the North Stafford battery loco kit which is being produced by Furness Railway Wagon co

David

 

[daifly]

It is my intention to adopt the 3-legged stool principle to assist both with adhesion and pickup. Is it possible for a wheelbase to be too short for this to be effective? A 'keep alive' is also on the list to fit as on my other 0-4-0 loco.

Dave

 

[AJC]

It is my intention to adopt the 3-legged stool principle to assist both with adhesion and pickup. Is it possible for a wheelbase to be too short for this to be effective? A 'keep alive' is also on the list to fit as on my other 0-4-0 loco.

Dave

What, simple three-point compensation? How very unfashionable! It works fine in 4mm scale so I can't quite see why it wouldn't in O. Nice and easy to execute too. Interesting prototype.

Adam

 

[oldravendale]

What, simple three-point compensation? How very unfashionable! It works fine in 4mm scale so I can't quite see why it wouldn't in O. Nice and easy to execute too. Interesting prototype.

Adam

See the Sentinel build. It uses the three legged stool approach. Short wheel base - although probably not quite as short - and as yet untested in anger but a very straightforward construction.

Brian

 

[daifly]

Back home for a few days I found time to progress a little with this. The wheels are back from Colin Dowling and have been reprofiled, thinned, hubs thinned and tyres blackened and polished. I thought that a simple loco like this - no outside motion, no coupling rods etc. would make this a straightforward first S7 loco build. Not so!



The sideframes are held in position by bluetack. Part 1 behind will be folded up to form an inner chassis.

The problem is that the width across wheel hubs on an assembled wheelset is 40mm which exactly matches the distance between the outer frames! The hub thicknesses cannot be reduced any further without compromising their strength so, what to do?

Fabricating a new wider footplate looks to be the 'easiest' option. The bufferbeam is much longer than the width of the footplate anyway so an extra 1mm or so of footplate width should not present a further problem. This allows the sideframes to be moved further apart.

Another possibility would be to source some appropriate sized U-section and replicate part 6 as a U instead of an L then position the sideframes at a suitable distance apart to allow the wheels to rotate freely and the rocking axle to do so without contacting the sideframe. The footplate would need to be reduced in width slightly and the butt joint attachment of the sideframes would need to be reinforced with some brass angle on the inside.

Any thoughts on these ideas or can anyone suggest a better solution?

Dave

 

[mickoo]

Funnily enough Colin and I had the exact same discussion today at the West Mersea meet, in regard to my Peppercorn A1 tender and Slaters wheels, you can thin the hubs to the same as the tyre, but as you say it makes them a little thin, even thinning the hubs to the bare minimum leaves them 39mm over all, you have to add a bit more countersink to the wheel to allow the retaining screw to tighten down a little more, but it is possible....or so I'm told, not tried it myself yet

Other than that, moving the frames out 0.5mm each side is the only alternative or sourcing different wheels....if even possible...where the hub dishes inward and not outward like Slaters.

Being as I've already built my frames and by chance I moved them out to 40.75mm between frames I'm pretty stuffed as even with slimmed bosses I have virtually no side play on an 8 wheeled tender, so, my only solution is to make large holes or slots in the frames where the bosses are (8-9mm dia) then bore out the inside of the cast axle box to suit. My wheels are solid so I might even be able to get away with reducing the diameter of the hub with a chamfer so that it's 6mm tapering out to 8mm at the wheel.

That might be your best option, open those holes out in the frames, or cut slots like the real thing to let the boss fit through and adjust the inside of the axle box fitting to suit if you want to retain true width frames, on a short wheel base like that you can probably get away with next to zero side play

I'm guessing part 6 goes outside the frames and is an angle between the footplate and frame?, why not solder that to the footplate at the required width, the cut the tabs off the frames and move them out to the L part 6 and solder the frames to that, that should be perfectly strong enough to hold the frames as they have no load bearing requirements.

 

[Overseer]

This may not be very helpful at this stage, but wouldn't it be easier and cheaper to use wagon wheels? As they have 1/8 inch axles you can use OO gears and bearings, and there probably wouldn't be the problem with the wheel hubs protruding to far. I built an Impetus Simplex with wagon wheels, Romford 40:1 gears, delrin chain and OO hornblocks on the rocking axle and it has always worked well. I do prefer Alan Gibson wheels for use with inside bearings as the wheels are concentric with the axle - Slaters wheels are mounted on the turned down ends of the axle and the centre of the axle is not turned so can be rough or not quite concentric, although you could check a few and pick some good ones. Alan Gibson S7 wheels are available to order.

 

[daifly]

This may not be very helpful at this stage, but wouldn't it be easier and cheaper to use wagon wheels? As they have 1/8 inch axles you can use OO gears and bearings, and there probably wouldn't be the problem with the wheel hubs protruding to far.

I have been mulling this solution over too. I have a set of Peartree S7 3-hole disc wagon wheels which have a 3/16" axle. They measure up at 39mm over hubs but will require the extended journals to be removed. I'm a bit nervous of disturbing the insulation between the metal wheel and axle. The deep sideframe effectively obscures most of the wheel so this might provide a workable (and quicker) solution. Thanks for the suggestion.

 

[daifly]

Being as I've already built my frames and by chance I moved them out to 40.75mm between frames I'm pretty stuffed as even with slimmed bosses I have virtually no side play on an 8 wheeled tender, so, my only solution is to make large holes or slots in the frames where the bosses are (8-9mm dia) then bore out the inside of the cast axle box to suit. My wheels are solid so I might even be able to get away with reducing the diameter of the hub with a chamfer so that it's 6mm tapering out to 8mm at the wheel.

That might be your best option, open those holes out in the frames, or cut slots like the real thing to let the boss fit through and adjust the inside of the axle box fitting to suit if you want to retain true width frames, on a short wheel base like that you can probably get away with next to zero side play

Thanks Mick. Another interesting solution. With a 4-wheel chassis, the only lateral movement would be on the rocking axle and such a small diameter wheel will not move much away from vertical at the rim. I'll have to take a close look to see if the small axleboxes would hide the slot.

I'm guessing part 6 goes outside the frames and is an angle between the footplate and frame?, why not solder that to the footplate at the required width, the cut the tabs off the frames and move them out to the L part 6 and solder the frames to that, that should be perfectly strong enough to hold the frames as they have no load bearing requirements.

Unfortunately, part 6 fits the other way up (if I understand your suggestion correctly). This shows the 'channel' that is created. The footplate overhang forms the top and the flange of part 6 forms the lower part. Any volunteers for creating that paint job?

 

[mickoo]

Thanks Mick. Another interesting solution. With a 4-wheel chassis, the only lateral movement would be on the rocking axle and such a small diameter wheel will not move much away from vertical at the rim. I'll have to take a close look to see if the small axleboxes would hide the slot.


Unfortunately, part 6 fits the other way up (if I understand your suggestion correctly). This shows the 'channel' that is created. The footplate overhang forms the top and the flange of part 6 forms the lower part. Any volunteers for creating that paint job?

Dave, ahh, yes, see what you mean about part 6 scratch that suggestion then LOL.

Good point about axle rocking, I'd only been considering lateral play, not rocking from the suspension, my problem is compounded by having a pair of brake rods per side (four in total) that run either side of the wheels, so will have to remove the etched blocks and replace with plastic or 3D printed as something is bound to short out somewhere!

As suggested above, wagon wheels might help, but I doubt any are big enough for my tender, though they are solid so that's one less aspect to worry about, maybe coach wheels might be a better solution for both of us?, they're generally larger diameter and might also have a narrower tread/rim/hub ?

Anyone have any dimensions for Slaters coach wheels, especially width over tyres and width over bosses?

 

[daifly]

As suggested above, wagon wheels might help, but I doubt any are big enough for my tender, though they are solid so that's one less aspect to worry about, maybe coach wheels might be a better solution for both of us?, they're generally larger diameter and might also have a narrower tread/rim/hub ?

Anyone have any dimensions for Slaters coach wheels, especially width over tyres and width over bosses?

Luckily for me, the wheel size required is 3' 1", so a wagon wheel works for me. I'm coming round to the Peartree wheel solution above. They do 3-hole 3'1" wagon wheels and 3'7" plain disc and Mansell S7 wheels here if that helps you at all.