I am modelling in H0 scale at the moment and I have one of the Rivarossi models of the US Army S100 class 0-6-0 tank. This is locomotive number 1948, which worked in mainland Europe and is substantially similar to fifteen engines used in Britain and bought by the Southern Railway in 1946.
The magazine ‘Model Rail’ has commissioned Bachmann to produce a RTR model of the S100 for 00 gauge, and I have bought one of these to compare it with the Rivarossi model of the European engines. To be honest, I have done this to see for myself how close modern 00 RTR really is to current Continental models. I can also use it as a 3-D drawing to help turn my H0 model to UK specification, and perhaps use it in a small layout with forced perspective. At the end of the day, if I want to sell it and I can wait until new production sells out, I’ll probably get most of money back on eBay.
With the two engines in front of me, I want to write a review to try to see the real differences between the markets for H0 and 00 models of what is essentially the same locomotive. This blog post is my report.
I shall say now,the S100 is one of the most ungainly engines I have ever seen. When it is modelled for 00 gauge, this ungainliness becomes rather exaggerated, almost to the point of absurdity and making me wonder if this a metre-gauge model in S scale. This is unfortunately the nature of the beast - and if I modelled in 00 then I’m sure I would be able to look though this discrepancy without any great worries. I want to ignore this from now on, and concentrate on the design and appearance of the two models.
There are good photographs of prototype engines for comparison on the Southern E-Group website at http://www.semgonline.com/steam/usa_01.html and its linked pages.
The motor has got to go somewhere and Rivarossi have put it in the cab, with the drive to the rear axle. This means the model can have detail for the top of the firebox (essentially, the part you can see without peering inside) but the cab has a raised blanking panel as a false floor about 3mm below the windows, to hide the motor. The cab has no other interior detail, and the glazing panels for the rear windows are rather prominent. Outside, the gearbox fits inside the firebox, and the model has the correct daylight above the frames.
Bachmann have put the motor inside the firebox and part of the boiler, with the drive to the middle axle. The cab is completely free and has the floor in the right place. The model has a complete representation of the back of the firebox, but there is no detail on the insides of the cab sides or cab rear, these are simply painted a pale cream colour, and the daylight above the frames is limited.
The Rivarossi model would look better without any rear glazing, and this is the approach taken by Bachmann. The Bachmann model has flush glazing in the front window frames and this is a big improvement on the square glazing panels fitted to the Rivarossi.
Staying near the cab, Rivarossi have modelled the bunker partly empty so the model can feature open coal rails with daylight between them. This looks really good, and the modeller can add some real coal if they like to top this up. Bachmann have modelled the bunker full, so the coal rails are a solid moulding with no daylight. If you want to model the bunker partly empty, you will have work to do. This looks like cost cutting by Bachmann, though we might argue it makes the model more robust.
As you study the two models more closely, you see some more discrepancies. Both models have finely-moulded bars on the rear windows, but Rivarossi have included representations of the hinges and fastenings. Moving forwards and downwards, the Rivarossi has an excellent representation of the firebox with full rivet detail, while the Bachmann has only bare chassis parts and no firebox at all. The models reproduce different versions of cab sides: the Rivarossi model has rivet detail (which is correct for some batches), and the Bachmann has no rivet detail at all (which is correct for the locomotive number 1968 represented). [Revised: 4 Sep 2016]
There is a general arrangement drawing of the engine in Wikipedia, and this drawing gives the major dimensions. I have converted these dimensions to millimetres, and then measured the models to see how close they are to scale.
Width over cab: 2,591 mm (8 ft 6 in on drawing)
Rivarossi measures 29.6 mm, Bachmann measures 33.9 mm
Length over buffer beams: 7,976 mm (26 ft 2 in on drawing)
Rivarossi measures 91.6 mm, Bachmann measures 104.7 mm
I used an old-fashioned mechanical vernier calliper and I ignore the last 0.1 mm or so - and all of these model dimensions are correct within 0.1 mm of their scale equivalents.
Maximum height (to top of cab): 3,787 mm (12 ft 5 1/8 in on drawing)
Both models have safety valves which are taller than this but not shown on the drawing
Rivarossi measures 42.2 mm, about 1mm too low
Bachmann measures 48.2 mm, about 1 mm too low
I question the correctness of the drawing because it is unclear whether this dimension is to the top of the rails as I have measured
Both models have working representations of the Walschaerts valve gear. The Rivarossi model has fluted parts with a dull finish, while the Bachmann model has plain pressings with a bright, plated finish. The representation by Rivarossi looks like a scale model, but Bachmann seem to have made everything oversize.
When the Bachmann engine runs, the movement of the combination lever and the way it overlaps the crosshead looks wrong - the return crank is too long and the union link is too short. Then again, perhaps the Rivarossi is wrong! A clear photo of the valve gear on a prototype would help here, but the Bachmann cross head guide extends further to the rear (to be behind the front wheel), and in fact all of the motion has been offset about 2mm further to the rear. The Bachmann appearance is spoilt further by a piece of stamped metal immediately behind the cylinders - this would be better out of sight inside the cylinder mouldings.
On both models, the slot in the cross head guide is too wide, but again this is exaggerated on the Bachmann model and with 12% more space to play with in each dimension in the larger scale, the 00 model looks rather toy-like.
Looking at the width of the model across the cylinders, this is always going to be difficult in an H0 scale model of such a narrow prototype without resorting to P87 wheel sets. Rivarossi have put the cylinders about 1 mm too far outwards on each side to make room for the valve gear, and made the cylinders a little too thin as well.
To quantify this error, the general arrangement drawing shows the distance between cylinder centres to be 6 ft 7.5 in, which is 2,019 mm. I measure the Rivarossi centres at 25.5 mm, which represents a scale of 1:79, about 10% too much. For comparison the Bachmann centres are at 27 mm, still slightly over scale but not noticeably so. Rivarossi probably made the cylinders too narrow to make space for the motion, but the discrepancy is only really obvious when you look at the model from underneath.
Both models have finely detailed brake gear. The Rivarossi model includes the linkages under the chassis already fitted, while Bachmann supply the linkages as a moulding for the purchaser to fit. This will help the modeller wanting to convert to EM, but see ‘Possible Conversions’ later.
Both models have handbrake detail, and both models have placed this in line with the wheels. The Rivarossi model looks more convincing here, simply because the distance from the frames to the cab sides is nearer to the scale dimension, and the brake mechanism is nearer to the pipe work below the cab.
Both models use Code 110 wheels, which will be wide enough to assure smooth running over the crossings of Peco pointwork. Both models will be able to run through track built to 00-SF standards, but I will have to ease out the back to back dimensions on the Rivarossi model about 0.1 mm to let it do this.
Both models have NEM coupler sockets. Rivarossi have put these in close-coupling mechanisms, while Bachmann have used their usual “fish tail” moulding. Both manufacturers have placed the sockets at the correct height, and Rivarossi have achieved the correct horizontal locations too, with the front of each socket in line with the front of its buffer beam. Bachmann have put the sockets outwards at both ends, perhaps as a compensation for the lack of a close-coupling mechanism. The Bachmann sockets on my model are letting the couplers droop and some shims or bending will be needed to clear magnetic uncouplers.
The buffers on the two models are of different designs. The Rivarossi buffers appear to be scale models of the correct buffers, the Bachmann buffer are something else and rather undersize in overall length and head diameter.
Both models have nicely-moulded pipe work detail below the cabs, and both sets of pipe work seem to be different to the photos I can find of S100 locomotives which ran in Britain and in Europe. So I can’t really write more about the pipe work, except it looks nice.
The Rivarossi model has working Continental-style lights at each end, while the Bachmann model has very finely moulded lamp irons in the right places. It is difficult to draw a comparison here, though Bachmann could have put a sprue of lamps into the box.
The Rivarossi model has plunger pickups concealed behind the wheel rims, while the Bachmann model has metal wipers visible below the chassis. One looks better, the other is easier to fix when it goes wrong.
Possible Conversions (Wheels and Couplings)
Bachmann have made the connecting rods thicker at the big ends, consuming any free space created by the use of 00 gauge, and this will make conversion to EM difficult, unless you either file down the thickness of the parts or move everything outwards. A modeller contemplating a conversion to P4 will be thinking of a complete new chassis, to rectify the errors around the firebox as well as the over-scale motion.
A conversion to P87 would allow a modeller (at least, a very keen modeller) to bring the Rivarossi cylinders inwards, but the overall improvement to the appearance of the whole model would be relatively small.
Bachmann have managed to represent the frames with correct daylight behind the front buffer beam and this feature improves the look of the model here. Rivarossi have not bothered, putting a solid infill of plastic instead, but the benefits in H0 would be less because the NEM coupler socket here is so much closer to the buffer beam. The 00 modeller can remove the coupler socket altogether and fit a scale coupler with very little work, while the same conversion on the Rivarossi model would take much more work to achieve the same appearance.
Running and Performance
Out of the box, the Rivarossi model ran like a Swiss watch and it is a joy to see in operation, both on a rolling road and on the layout. The Bachmann model runs quite well, but needs more running in.
The Rivarossi model is nose-heavy, in spite of the rear mounting of the motor, and the Bachmann model is tail-heavy, in spite of the central mounting of the motor. These details do not seem to affect performance of either model.
My test load is a train of eight H0 bogie vehicles: three Fleischmann Bulleid coaches and five Roco ferry vans. This is all I can fit on a level part of my layout. Both engines can start and move this train without wheel slip.
The Rivarossi model is much lighter than the Bachmann model (148 g vs. 200 g) and has far less adhesion on a gradient. On a curving rising 1:20 gradient, the Rivarossi model can propel only one Bulleid coach, while the Bachmann model can manage two. I don’t have two comparable 00 coaches to try, but clearly the Bachmann can manage twice the physical load even though I cannot show whether it can manage twice the scale load.
I often read in the press and online about modern British RTR coming closer to Continental standards but there is no way I could say this particular Bachmann model comes anywhere near Continental standards, except to say it is more powerful. The model has been built to a keen price. This is not necessarily a bad thing and I hope everyone who buys the Bachmann model gets a lot of pleasure from it, but from a personal point of view I would feel I was getting better value for money if the model could have cost rather more (say, £180 not £125), and sorted out some of the shortcomings. For comparison, the Rivarossi model is listed at 220 Euros but currently discounted to around £120 including carriage from Germany.
Aside from detailing and price, if Bachmann had used finer components for the valve gear and some plain washers to pack out the horizontal gaps inherent in an 00 gauge model, a conversion to EM would be a lot easier.
If the customers in both H0 and 00 markets consider these models to be “good”, and my report here is seen to be reasonably objective, then the biggest difference between the UK and European markets has surely got to be that UK modellers buy on price, Continental modellers buy on product. I tend towards the product rather than the price, and as a British H0 modeller I will turn a blind eye to specific things which I cannot put right (like the cylinders sticking out a bit too much) when the rest of the model seems spot-on.
I hope this is useful, even if it is probably written from a different viewpoint to the usual UK model magazines. Thanks for reading.
I have not attempted to take either model to pieces, nor fit a decoder, and perhaps someone else can add this or other details I have missed.
Edited by 47137