Review of the Heljan 7mm scale ex-GWR 43xx No. 5306 [4313]

The Accounts Department at Ashprington Road authorised the purchase of a 7mm scale Heljan ex-GWR 43xx 2-6-0 mogul locomotive.
"I thought 'Ashprington Road' was a 4mm scale layout ?" I hear readers exclaim. Well it is, but the Ashprington Road workbench layout is multi-scale with 9mm, OO and O gauge track. And besides, this is a pre-investment in Dad's 7mm scale 'Ashburton' layout. Got to justify it somehow!


Although some might say that the GWR 43xx isn't a very attractive loco due to the Churchward cab, it is actually my favourite GWR loco. From a modelling perspective, it is a medium-size loco which is pretty vertsatile and was seen all over the prototype GWR and BR(W) network, making it easy to fit onto any model layout.

The prototype was a very successful mixed traffic locomotive, serving more than 50 years in service. Originally built by G.J. Churchward, they were in fact, a mix of re-used existing GWR standard locomotive parts. They were essentially a tender version of the 3150 2-6-2 Tanks.
Over several decades there were many detail alterations, including different styles of chimney, alterations to the length of the frames, weight distribution and inside or outside steam pipes. The last 20 locomotives, built in 1932, featured more modern-looking side window cabs and outside steam pipes and were known as the 93xx class.
Between 1936 and 1939, 88 locomotives were withdrawn and their wheels and motion were used in the construction of 'Grange' and 'Manor' 4-6-0's, but others lasted well into the 1960's, working across most of the former GWR network from the far west of Cornwall to London, Wales and Merseyside.
During the First World War, eleven 43xx's were loaned to the War Department for use in France hauling munitions and hospital trains.
The GWR 'Moguls' were maids of all work on the GWR network and later, the Western Region of British Rail. They used a Standard No. 4 boiler and support struts similar to those fitted to the 28xx class 2-8-0's.
The class very quickly earned an excellent reputation for its ability to handle most types of traffic, from local stopping goods trains to main line expresses. According to the famous railway author O.S. Nock they could "handle the heavy goods work as well as the 'Abadares' and could run up to 70mph with passenger trains, in other words, they were the ideal mixed traffic locomotive".
Despite their usefulness and significance, just one 43xx survives in preservation: No. 5322 at the Great Western Railway Society's Didcot Railway Centre. No. 5322 was one of the locos sent to France in 1917. No. 7325 from the last batch of 20 with cab-side windows has also been rescued and it is currently on static display at the Severn Valley Railway.

The Model

The model is supplied in the standard style of Heljan loco box, however, being 7mm scale, this box is somewhat larger than what one sees with 4mm scale!
The thing which is immediately obvious is that the box is HEAVY. It weighs in just over 3Kg. That explains why the postage costs were so high!.
With this kind of weight, you will not get away with track which is not supported properly.
On removal of the locomotive from the box, it is securely screwed to a wooden plinth:

No! The front pony truck is not missing! It is packaged separately in the box. When one considers the weight of this loco, attaching it to a firm wooden plinth like this really is the only way to secure it in its box. Any other attempt at retaining it, such as foam, would simply allow it to move around in the box. It does also have the benefit that it is quite a nive display plinth!

It has to be said that this model is simply stunning. The pictures in the article really don't do the model justice. It is a big model and due to its size, it has incredible 'presence' about it. Once can easily sit looking at this model for ages, just studying it!

Also in the box is a small pack of detailing: cab-side number plates, under front buffer beam AWS equipment and three or four other pieces which I'm not sure what they are and the instructions give no clue about. Other than that, the model is complete.
The buffers are sprung - this is basically standard in 7mm scale.
The couplings are working screws, however, the 'Tommy bar' is really too short. The couplings are sprung behind the buffer beams.

The tender is coupled to the loco using a bar. I haven't yet disconnected this to see whether there are different holes for different distances, however, I did notice that on initial running, there is a little slack which can vibrate when the loco motor is running very slowly. On a 4mm scale model of this type, I have wrapped a piece of paper around the peg to effectively 'fill in' the slack and stop the rattle.

One thing which is noticeable is that electrical pickup is ONLY on the tender. The loco has no pickups. I'm not so sure this is a good idea, but I'll see how it works in practice over time. Even the tender has some weight, so maybe in 7mm scale, this may not be the problem that it would be in 4mm scale. If it becomes a problem, I can always fit extra pickups myself.

The reversing rod is painted red. This is not my personal preference so I will probably paint it the same colour as the loco. However, some of the prototype locos did have the reversing rod painted red: this was a signature mark of locos maintained at Caerphilly works. I will check whether No. 5306 is from that area before I get the paint brush out.

The model has a beautiful fall plate which actually does hinge up. Similarly, there is incredible back-head detail:

Note how the firebox doors are open. There is a flickering LED to represent a fire. The white edge to the cab roof is actually the rolled-up bad-weather tarpauling.

Something I wasn't sure about was the mounting of the front pony truck. The hole in the truck was a good 0.5mm larger than the screw through it. This kind of assembly usually results in a pony truck which shunts backwards and forwards relative to the loco, however, in practice, I did not observe this to be a problem.

A couple of minor points:

  • The tender wheel rims could do with blackening, the same as the loco wheels. Easily fixed with some black paint
  • The number plate on the smokebox door has a rather strange looking fitting. A minor bit of remounting could fix this

Fitting a Decoder for DCC

Fitting a decoder is not the simplest of processes. Heljan have chosen to fit a motherboard which only accepts the Loksound 4.0L sound decoder. The connection plugs are completely different from any other decoder I have seen and there is no option to fit a standard non-sound 8-pin DCC decoder. So basically, it is an 'all or nothing': DC or full DCC with a top-of-the-range sound decoder with no other options in between.

The blanking board is very strange. It looks like it contains electronic circuitry to drive the flickering firebox. It has multiple plugs and sockets, although only the plug on the left between the two sockets (with pins protruding) seems to be used in DC operation. The plug on the right seems to have speaker connections:

The thing which caught my attention was the 8-pin socket which, if one views the picture closely, has some kind of bridging of pins in place. 'Ah' I thought, 'a DCC 8-pin socket, let's plug an 8-pin decoder into it'. So I did (I removed the bridging first). Placed the loco on a programming track and attempted to set the loco address. The loco buzzed in the same way as when a DC loco is placed on DCC track. This is not an 8-pin decoder socket, but I have no idea what it is. Perhaps readers may like to comment in the blog at the end of this article ?
So my hopes dashed, since I don't have a Loksound V4.0L, I was wondering how I could fit an 8-pin decoder. There are a couple of articles on t'net describing how people have completely removed the supplied motherboard and fitted alternatives. For the moment, I don't really want to do that, so I figured that the obvious thing to do was to reverse-engineer the pin-outs and make up my own board to plug into the main motherboard. Fortunately, all the connections on the motherboard are marked, so it is easy to see what the pin-outs are. I therefore, made up my own board:

The third picture above shows the completed assembly with my home-made board. The 8-pin socket needs to be on the underside of the board because there is insufficient height in the tender to accomodate anything higher than the socket on my board - ie can't plug anything into it.
I have fitted a TCS MC2 decoder. This is rated at 1.0A continuous, 2.0A peak. Prior to fitting this, I tested the loco on a DC track with ammeter and turned the throttle up while holding the loco stationary. Even under very heavy load, the current draw was no-where near 1 Amp, so the TCS decoder is well within range for this loco.
The loco runs perfectly with this arrangement.
At this stage, I haven't wired the flickering firebox function connection on my board. But I haven't done anything to the main motherboard which would preclude its use in the future.


Like all Heljan locos, this model has a superbly quiet motor and runs extremely smoothly out of the box on DC control. When I ran the loco on Steve Rowe's 'West Green' layout, I observed the odd 'stutter'. On some occasions this was related to the tender-only pickups and on other occasions, I believe that it was related to the TCS MC2 decoder's inability to control the motor effectively. I have a spare TCS KAT22, so I will install this. The KAT22 has the advantage that it is rated higher at 1.3 Amps and has a built-in 'stay alive' capability. I have never been a great fan of 'stay alive' as I hail from the camp who believe that one should fix the causes of problems (lack of pickups, quality of track laying etc) rather than band-aid them with 'stay alive'.
The tender also acts as a bit of a sound chamber, so I will install some lead weight along the insides which will have the effect of deadening the 'sound chamber' effect and adding further weight.


Fabulous model, full of presence, very well detailed and runs really well. The only thing which I believe could be improved is the use of the non-standard ESU motherboard. Or at least a blanking board with a real, working 8-pin DCC socket could be installed for those who don't want to fit sound.
Not cheap, but highly recommended.

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Graham Plowman (19/01/2020)

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