Private Owner Wagons - RCH Regulations

[1H was 2E]

I have an old Wagon Repairs publicity map. Around the map itself, there's various 'blurbs' advertising the services available, some quoting RCH regulations as an incentive to use Wagon Repairs.
I was aware of the either side brake lever one, but I don't understand the offer to convert steel framed wagons to wood, suggesting that there was an RCH involvement. I can only think of a perceived problem with corrosion, but wood frames had their problems too; I recollect seeing the occasional old wagon with banana shaped solebars!
Does anyone know more? Edited because I overlooked resizing the attachments

[65447]

The first RCH specifications in 1887 required the frames to be of 'sound English oak', later amended to white oak, but also provided for steel frames. Specifications from 1903 included full drawings and details for steel-framed wagons of varying types. Certain railway companies, the GWR and GER in particular, had by that date already produced thousands of wagons and vans with steel underframes. Apart from being a wheeze to make money, the only logical reason could perhaps be that timber frames could be repaired with standard components all over the railway network whereas repairs to steel underframes would need to be carried out at specific works. To a wagon owner, the losses associated with out-of-service wagons could be considerable, especially when noting the demurrage charges they made on the railway companies for not returning their empty wagons expeditiously.

However, I would also add that 1916 was right in the middle of WW1, when back-loading of wagons was allowed to improve efficiency and reduce costs and pooling of the GC, GE and GN railway companies wagons had been agreed, followed in due course by pooling arrangements with several other companies. It is extremely unlikely in such situations for any organisation or body to introduce changes to rules that involved the unnecessary consumption of raw materials and labour, and after 1907 the next major change to RCH Specifications came in 1923.

[D2100]

I'm sure I recall Dave Larkin citing the notion that steel-underframed POs were less long lived than all-wooden ones, and that the reason may have been corrosion caused by the acidic nature of wet coal. Obviously all-steel mineral wagons in later years were even more prone to this, but whilst the wooden PO was the norm, it may well have been a factor.

[1H was 2E]

Thanks for the replies. The conversion does seem to be aimed at coal wagons by its reference to "side, or side and end doors". What may also be relevant, supporting the suggestion that wet coal has a particularly corrosive effect on steel, is that steel 16t Mins loaded just before the start of the NUM strike but then stranded for many months loaded were in a desperately rusty state afterwards.
On the SVR and salvaged from Chatham dockyard is an ex Brecon & Methyr goods wagon with steel underframe that is authentic and original. It's just interesting to wonder how common steel frames were before grouping.

[65447]

According to the model manufacturers and all those line societies, museums and other income-seeking organisations, almost every limited edition wagon commissioned since time immoral sits on a 10' wb steel underframe... ergo they must have been very widespread