Model Railway Forum

Hope I'm not a numpty for asking this question, but here goes. I have 2 private owner five plank wagons - same private owner and same wagon type modelled. Why then is the Hornby version bigger than the Bachmann - length, width, height and even letter size - and obviously so. I thought a prototype would be scaled accordingly. Any suggestions? I'm sure there must be a very simple explanation. Thank you.

The problem is that over the years the various manufacturers have produced a multitude of PO wagons, but have generally failed to make an accurate scale model of a PO wagon. Mostly they have taken a wagon from their existing range and painted it as best they can. Often the wagon chosen is a more modern design, and over the years wagons got longer, wider and higher. Fitting the livery to the wagon side results in the different lettering sizes. Bachmann have the best track record amongst the major RTR manufacturers, their Blue Riband wagons are based upon prototype PO designs, although mainly to later RCH standards, so slightly larger than most pregrouping PO wagons.
To a certain extent this may not matter, since the coal traders would usually have a range of wagons in their fleet, obtained from different builders at different times, and there would be variations between wagons, and even the livery would change over time. It's only when you become an expert on wagon history that the errors may start to grate, but the liveries are usually so well done it is hard to be too critical.
If you want greater accuracy then you may have to resort to assembling ready printed kits from Slaters and POWsides, which are generally based on the most appropriate wagon design, but the range is still restricted, there were hundreds of wagon builders whose designs would be slightly different, the RCH standards they had to adhere to evolved over the years, and customers could demand design changes to meet their peculiar requirements, although careful choices from the various RTR ranges can be pretty accurate. But you made need to do some heavy research to find out what is what.

Could the B’mann wagon be Ho.

Hornby early wagons were always a bit oversized. They have produced the wagons for years. The latest versions are more realistic.

Bachmann being the 'new kid on the block' in the UK compared with Hornby have produced wagons more to scale. I believe Oxford Rail wagons are a bit too small. I don’t care, they all look OK to me.

Tens of thousands of wagons were built so there must have been many differences.

This is my drawing of a RCH 1923 specification PO coal wagon which is based on official information.

The model manufacturers have a nasty habit of using inaccurate components and then stretching the other dimensions to make it fit. In the case of the PO wagon (POW) Mainline and Dapol used a Big 4 company underframe which is a scale foot too long and had the axles a similar amount too far apart. Bachmann originally used old Mainline tooling but saw the error of their ways. Hornby too strayed the paths of unrighteousness but have returned to the faith. Parkside kits are OK.

The Railway Clearing House (RCH) have issued specifications since 1887, and modified them from time to time to allow larger and greater capacity wagons as time went on. In Victorian times a ten ton wagon was regarded as very large, but the RCH specification for 1923 had settled upon 12 tons as standard for a steel underframe and wood body coal wagon. Seven plank bodywork approx. 4' 3" high was typical for coal, denser material such as limestone or china clay was carried in five plank wagons to avoid overloading.

A steel version was in development in 1939 when War broke out and all POWs were requisitioned. This would have a capacity of 14 tons. During the War the 12 ton wagons were uprated to 13 tons and the proposed steel mineral wagons were uprated to 16 tons. Dimensionally these were similar to the wooden bodied coal wagon so they could still fit in the collieries where they were loaded. The 16 tonner soon became the standard. The pre-War POWs having been bought by the new British Railways were progressively withdrawn and replaced with new all steel 16 tonners.

RAF96 wrote: ↑Sun Mar 01, 2020 9:25 pm Could the B’mann wagon be Ho.

I'm not aware of Bachmann producing HO wagons. Trix were one of the first to offer PO wagons, and they worked to some strange scales such as 1/80, and it's possible that some Playcraft and early Lima HO wagons might be around, but they would all look considerably smaller than their OO equivalents.
The early specification from the Railway Clearing House circa 1890 suggested an overall body length of 15', and by their 1923 spec the length was increased to 16' 6", but these were only recommendations, and could be varied by the customer, and the height of the sides was not covered, as that was very dependent on the traffic requirements. The width hardly varied, as it was dependent on many factors such as infrastructure, and wagons for Bristol Channel ports had to be narrower than for other destinations.
The Big Four companies tended towards even longer wagons, such as 17' 6" bodies, and this, coupled with the more modern ironwork and often steel solebar, is why the PO liveries applied to, say, an LMS open, look so wrong to the expert eye. When done well, such as on the Airfix wagons, it is difficult to complain, but if insensitively done, as on many of the commissioned examples, it can look very suspicious.

Walkingthedog wrote: ↑Sun Mar 01, 2020 9:43 pm Hornby early wagons were always a bit oversized. They have produced the wagons for years. The latest versions are more realistic.
Bachmann being the 'new kid on the block' in the UK compared with Hornby have produced wagons more to scale. I believe Oxford Rail wagons are a bit too small. I don’t care, they all look OK to me.

Tens of thousands of wagons were built so there must have been many differences.

As I noted before, when Bachmann produced their Blue Riband stock they upped the game, but before that they made use of some inaccurate bodies, inherited in part from Mainline, with their intrinsic faults.
At any one time there were up to 700,000 PO wagons on British rails, and, given a life of between twenty and thirty years, the author Len Tavender has estimated that over 1.6 MILLION PO wagons were built, from around 1860 to 1945. In addition they would have been repainted several times in their life, perhaps even rebranded or rebuilt on occasion, adding to the variety. All painting and lettering was done by hand, no vinyls then, so much depended on the skills of the workers, and there are some examples where spacing and letter sizes and shapes have gone slightly awry, giving a slightly comic effect.
The amount of documentation that exists can only touch upon a tiny percentage of that enormous fleet, not even the tip of the iceberg, so there is much that is unknown, and almost anything is possible, within reason, but, on the other hand, in recent years much has appeared in print, largely thanks to Lightmoor Press, so there is plenty of accurate information available to get things right.

Thanks for the replies everyone. I can certainly live with the differences/inaccuracies - was just interested in the different dimensions for the same OO wagon.

By the time the 'Big 4' had been created the companies had settled upon a fairly standard design for ordinary stock which was 17' 6" over headstocks and 9' 0" or 10' 0" between axles (wheelbase). Older stock from pre-Grouping companies was still around, but were gradually being phased out. The Privately owned traders wagons, especially for coal and minerals tended to be even smaller and of lower capacity, and most were fairly ancient. Dumb buffers which were common in the early Victorian period were outlawed by the main line companies and except in Scotland had all but disappeared by the First World War, but there were still many wagons of ten tons or less being used, converted to spring buffers. The other anachronism was grease lubricated axle journals which had to run warm to provide any real reduction in friction, and frequently ran hot and set the wagon on fire. Oil lubrication was not universally applied until after Nationalisation. Friction resistance was a significant problem.

Resistance to change was very strong caused in the main by financial considerations but also the restrictions imposed by the infrastructure. At collieries there were height and width restrictions imposed by the screens where wagons were loaded, and similarly at discharge points, especially where wagons were emptied by rotary tipplers, or manipulated on lifts. Length was also an issue. Most weighbridges had been installed with short wagons in mind, and similarly wagon turntables where a 9' or 10' wheelbase was the longest that could be accommodated. The standard 16 ton Mineral which appeared during WW2 still adhered to the tiny dimensions of wagons in use before WW1.

The size of the weighbridge was an important consideration because the payment for the conveyance and delivery of loads depended on the accuracy of the weight, of the wagon both loaded and empty. The weighman was an important official. How many layouts incorporate a weigh bridge in their goods yard sidings I wonder?