Departmental Locomotive No. 81

[Spartan]

I'm just starting to put together my very first 'brass' kit, namely the Judith (Mike) Edge model of Andrew Barclay 0-4-0DM shunter (latterly TOPS class 01).

I'm looking for more details, particularly images, of my chosen subject (victim!), works number AB424:

Delivered in 1958 as Departmental Locomotive No. 81, it worked at Peterborough East yard until July 1967, when it was taken into capital stock, re-allocated to Doncaster (36A) and re-numbered as D2956 (did it ever carry this number? I have found evidence here that it may have been at Doncaster as early as April 1966, together with the original D2956).  It was withdrawn in November 1967 and sold for industrial use to Duport Steel, Briton Ferry, but is recorded as cut-up there by August 1969.

N.B.  The D2956 number originally belonged to sister locomotive (formerly 11506) that was withdrawn and sold into industrial service earlier in 1967.  This locomotive is now preserved at the East Lancs.  This is not the locomotive I'm interested in.

Although representative of the class, no. 81 differs from the rest of the 01s in a number of areas, sharing more 'modern' features with the TOPS class 06 (the first batch of which were built immediately after AB424), e.g., steel rather than wooden doors, grometted front/rear cab windows, square cab side windows.  It was also vacuum braked and had a more substantial front buffer beam than its sisters (to counter balance the weight of the vacuum exhauster and additional vacuum receivers? These latter would probably have been placed inside the rear of the cab).

There's a good picture of her here: No.81 stabled between duties at New England MPD on April 24th, 1960. (Norman Preedy)



Thanks

[Spartan]

So far I have found:

• a photograph (plate 123) by A.V. Fincham in Colin Marsden's "A pictorial record of the diesel shunter" (SBN 86093 108 0)
• official photograph (pp. 230-231) by Barclay in Colin Marsden's "The diesel shunter" (SBN 86093 579 5)
• a photograph (HU00209) by Kevin Hughes available from RCTS photographic archive
• two images (N.E. Preedy/unknown) and some details under "PETERBOROUGH ENGINEER’S DEPOT" here
• a photograph by Terry Campbell here but I'm sure (based on detail differences - cab window, front buffer beam) that this is not No. 81 but rather the original D2956 prior to withdrawal
• useful details/history here

The Judith (Mike) Edge kit for the Class 01 includes detail variations and General Arrangement drawing to allow building of No. 81. I'm considering writing up my attempt at its construction for an article but perhaps it would make sense to publish my progress here first.

[Spartan]

I was fortunate enough to be able to have a good chat with Mike Edge at this year's Scalefour North. He was able to allay most of my 'noob' fears regarding metal kit making and the dark art (to me) that is soldering. He was also able to advise on the extras that I would need to complete the kit.

One of the things that had always put me off kit building previously, was the prospect of having to independently source a whole list of essentials without really knowing what I was ordering (or even what they looked like).

Mike very kindly took me across to Chris at High Level and with the GA drawing from the kit, made a suggestion for gearbox and motor that would fit. These were duly purchased, followed by wheels, crankpins & buffers courtesy of Alan Gibson and a whole load of essential tools & 'stuff' from Eileen's Emporium: cutting & smoothing broaches, reamer, digital calipers, piercing saw, ruler, engineers square, phosphoric acid flux, brass wire, PCB, etc. In for a penny, in for several pounds but all under one roof and in my shopping bag to take home on the day.

Ironically, the only thing that I couldn't take home with me was the Barclay kit itself (awaiting delivery from the etchers).

[Spartan]

While I was waiting for the kit to arrive, I had plenty to keep me busy - namely the construction of the superb High Level gearbox. In my case, the "LoadHauler+" variant with 108:1 reduction for the Mashima 1020 motor.

Until I can work out how to upload my own images to this forum, please make do with this link for details of the gearbox.

Found it!

[Spartan]

The thing that differentiates the "+" from the standard gearbox is the presence of an articulated final drive gear. This gives the flexibility to install the chassis of the gearbox and, equally importantly, the attached motor in a number of different configurations. This is particularly useful where there isn't a lot of room - as is the case with the Barclay (the real thing could only accommodate the diminutive Gardner 6L3 engine).

The configuration suggested by Mike is shown in the first image.

IMG_0604.jpeg

This definitely would work and, as was Mike's intention, gets the gearbox as far forward as possible to allow room for the motor without intruding into the cab. However, I wasn't really happy about the amount of gearbox that would be visible underneath the chassis (notwithstanding its proximity to the permanent way). After considerable head-scratching, Scotch-sipping and umpteen different alternatives (that this wonderful piece of engineering allows), I came up with what is shown in the second image.

IMG_0606.jpeg

For me, this has the advantages that it's 'invisible', clears all the frame spacers (shown as blue lines on the GA - no cutting/fettling required) and leaves the front bonnet area and cab unencumbered. I do have a concern that the motor will live under the 'tent' of the fuel tank and that this enclosure will get warm. Time will tell but I'm considering drilling a ventilation hole in the front of the tank, hidden by the exhaust stack that could have a corresponding hidden hole - a sort of scale operating exhaust?!

[Mark Tatlow]

Aren't you making life a difficult for yourself with the loadhauler? It still looks very tight in the upper bonnet?

Hi Level do do a loadhauler compact but even if you chose not to use it I wonder whether you need to go all the way down to 108:1 with such a small wheeled loco?

Mind you, it will crawl along and that would be the aim for a small shunter.

[Spartan]

Mark - you may be right in all respects but I'm just working with what was recommended to me. Perhaps this is just another aspect of my inexperience but I trusted the advice that was given to me.

Thanks very much for your input though - all very gratefully received from anyone.

[Spartan]

On the subject of gear ratio and small wheels ...

The info. I can find (here) on the Mashima 1020 motor suggests max rpm @ 12V to be ~ 15,500.

My arithmetic* tells me that with a reduction of 108:1 that's 143 rpm at the wheels; at a nominal driver size of 3.3', I calculate a max speed of ~ 16mph (stated max. speed for the prototype is 14.5mph)

So I think that's a pretty fair approximation or am I missing something? Of course, at the other end of the scale, it should be able to crawl along at 'silly slow' ...

*If you're happy to use an approximation for pi then the following will give you speed in mph for a given max rpm (R), wheel diameter in inches (W) and gear reduction (G):

R x W / G / 336

[grovenor-2685]

There are two issues here, first the max speed given is most likely a 'no load' speed and it will drop on load so you may find the loco a bit slower than expected. Second is that the noise produced by motor and gears goes up with speed, more than in proportion. My inclination would be to aim for a maximum loco speed with the motor doing about 10000rpm and then not run it flat out, it will be a lot quieter that way.
Regards
Keith

[Spartan]

Keith - that makes perfect sense; thanks very much indeed for your comments.

Working your numbers (assuming it includes allowance for load/mech. losses), it would apear that a more sensible reduction ratio might have been ~ 80:1

Hmmm ...

Am I best to persevere and work with what I've got or should I look to find an alternative ratio (and even gearbox) before going any further? Unfortunately, I've already made up the recommended gearbox whilst I was waiting for the kit to arrive ...

[David B]

All this maths! I find the Speed Calculator on Chris's website (High Level) under the 'Gearbox' tab saves an awful lot of sweat.

David

[Spartan]

Too much already? I do apologise.

Thanks very much for the link - that was exactly the sort of thing I was looking for earlier. However, for it to be really useful, perhaps we need to establish what figure should go in for the RPM. Assuming it is dependent on the motor (not just always 10,000) what is the rule of thumb - 2/3 of the motor maximum? Sorry - more maths!

[Paul Willis]

Too much already? I do apologise.

Thanks very much for the link - that was exactly the sort of thing I was looking for earlier. However, for it to be really useful, perhaps we need to establish what figure should go in for the RPM. Assuming it it dependent on the motor (not just always 10,000) what is the rule of thumb - 2/3 of the motor maximum? Sorry - more maths!

As a completely irrelevant benchmark, 2/3 maximum revs is generally what motorbikes are noise tested at to see if they meet the 105dB limit for racing

Back on track with model railways, I think that it is a 108:1 gearbox in my High Level Pug, and it does absolutely crawl along - it took something like five minutes to circumnavigate the North London Group's circular test track.

So assuming that you won't go everywhere flat out, you could stick with this gearbox (in your new configuration) for this kit and learn the lessons for next time - you seem to be doing very well with it.

The maths is okay, and it's good to understand what goes on. However there is (fortunately for us artist types) a wonderful lack of precision that you can get away with in certain areas as well

Cheers
Flymo

[Terry Bendall]

but all under one roof and in my shopping bag to take home on the day.

Shows the advantage of a good exhibition for the kit and scratch builder. A slightly greater number of traders, but covering all your model making needs will also be found at Scaleforum.

Perhaps this is just another aspect of my inexperience but I trusted the advice that was given to me.

Mike Edge is a highly experienced kit designer and model builder, both for himself and for others. I would suggest that his advice is always worth considering. However, as with many other aspects of railway modelling, there is usually more than one way of doing the job, and it is up to the builder to decide what works best for them.

Terry Bendall

[Spartan]

'Mo & Terry - thank you for your kind comments. As this is my very first loco kit, I'm obviously learning and feeling my way but I feel heartened enough to continue with what I've got.

To 'Mo's point, just like the real thing, it's a pretty uncomfortable experience to go flat-out in a shunter and it was not my intention to drive it like that in model form. However, I'm now aware that I should consider leaving some 'headroom' on the motor/gear combo in future. In these days of DCC, I guess it's a very easy task to set the model max. speed anywhere less than that equating to the motor max rpm.

To Terry's point, my brief acquaintance of Mike left an impression of a very helpful fellow modeller. From my growing acquaintance with the contents of one of his kits, he's obviously a brilliant model engineer. I certainly didn't mean to abdicate responsibility as builder for the choice of gearbox and it was all my decision to move away from the suggested configuration. I was just trying to reinforce the point that I'm working with what I've got here rather than just making life difficult for myself.

[BryanJohnson]

I produced my own spreadsheet for calculating gear ratios a while back. I've attached a worked example for No 81 which comes out at 82:1.

Gear_ratio_Dept_81.xls

If you do want to change and haven't started on the gearbox yet, I think the frames are the same for all ratios of a given gearbox and Chris may be willing to exchange the actual gear wheels.

Bryan

[Spartan]

Bryan - wonderful - that's definitely 'a keeper'! Very impressive RAG (that's Red Amber Green indicator for those not used to seeing this on status reports) on the motor RPM too! I'm pleased to see that your spreadsheet concurs with my guesstimate above for 2/3 max motor rpm (and If I tweak the motor max rpm to 65%, the ratio drops out at 81:1 which seems fitting for No. 81).

As I mentioned a few posts back, I've already made up the gearbox hence my desire to use what I've got. If it doesn't work then I will put it aside for another project and use an alternative gearbox.

Thanks everybody for your help and input!

[Will L]

..If you do want to change and haven't started on the gearbox yet, I think the frames are the same for all ratios of a given gearbox and Chris may be willing to exchange the actual gear wheels.Bryan

Surprisingly the only thing that changes is the worm wheel, which comes out on the motor shaft and hence can be swaped very easily.

Will

[Spartan]

..If you do want to change and haven't started on the gearbox yet, I think the frames are the same for all ratios of a given gearbox and Chris may be willing to exchange the actual gear wheels.Bryan

Surprisingly the only thing that changes is the worm wheel, which comes out on the motor shaft and hence can be swaped very easily.

Will

That is surprising but perhaps I've not understood your statement fully. On my gearbox, the worm is on the motor shaft and the worm wheel (the double gear wheel, one half of which meshes with the worm) is on the first stage gear shaft. So to change the worm wheel would mean dismantling the gearbox (slightly) but, in order to affect a gear ratio change, presumably I'd have to change both this and the worm (to ensure they continued to mesh correctly)?

[Will L]

Surprisingly the only thing that changes is the worm wheel, which comes out on the motor shaft and hence can be swaped very easily.

Will

That is surprising but perhaps I've not understood your statement fully. On my gearbox, the worm is on the motor shaft and the worm wheel (the double gear wheel, one half of which meshes with the worm) is on the first stage gear shaft. So to change the worm wheel would mean dismantling the gearbox (slightly) but, in order to affect a gear ratio change, presumably I'd have to change both this and the worm (to ensure they continued to mesh correctly)?

Sorry loose language. I should have said the only thing that changes is the worm. The worm wheel does not change. That surprised me to but I'm pretty sure its right. As far as I can tell form the 5 or 6 All the Highlevel gear boxes I have assembled, they all use the same double spur gear sets.

Will