The Railways Clearing House provided a neutral forum for railway managers and engineers to meet and agree common standards. In 1887 the first specifications for a 'standard wagon' were issued, covering all aspects of design, materials and construction. This was brought about following several serious accidents caused by deficiencies in the design, materials, construction or maintenance of wagons.
The need for many thousands of basic mineral wagons had resulted in a proliferation of wagon building companies across Britain, however there were no standards or specifications for the materials, design, construction or maintenance of wagons. By the 1870s train lengths, loads and distances travelled had greatly increased. However the wagons in service ranged from robustly built vehicles well suited to long-distance travel to the colliery tubs or cauldron wagons which had formed the earliest trains suitable only for short journeys at slow speeds. Few of the many wagon builders used compatible parts, timbers being cut from wood on hand and metal parts forged individually. Even as larger wagon companies were formed (the Gloucester Railway Carriage and Wagon Company was formed in 1860) and began mass production of metal parts these differed in design between builders and the strength of the design or materials used could still be questionable.
The RCH had already begun to address the issues of standardisation or rolling stock, it being obvious that couplings and buffers needed to be compatible for wagons to travel across the whole railway network. Similarly wheel standards needed to be compatible with the track, which also needed to be standardised across the country. Some materials and designs had proved unsatisfactory and through the RCH the railway companies sought to eliminate some of these features as quickly as possible.
The changing nature of railway operation and increasing interchange of wagons between railways was now making the need to define and implement proper standards for construction, maintenance and inspection across the entire network.
Key to the adoption of the RCH wagon was the agreement of the RCH member railway companies that, once one company had applied its plate to the wagon as having been inspected and conforming to the RCH requirements, all of the member companies would accept that wagon for service. Similarly wagons not adhering to RCH standards could in future be refused by the railway companies. Thus following the RCH standards ensured that private wagon builders and owners could know that their wagons would be accepted anywhere on the railway network.
The RCH 1887 standard wagon specification covered all aspects of underframe and body design, based on known good designs and practices and eliminating fittings, designs and methods which had proved unsatisfactory in longer-term service. Minimum sizes were defined for structural timbers and the layout of the underframe timbers to provide appropriate structural strength and rigidity. Construction requirements included 'back-to-back' spacings for the axlebox supports or W irons, which in turn set many of the dimensions for the underframe structures supported on sprung axleboxes. Joint reinforcing brackets and acceptable methods of making joints between structural timbers were covered, along with the fittings like grab handles and rings for ropes to be attached suitable for moving the wagon using a horse were also defined. The fitting of a hand brake was also required, though this could be fitted on one side only and at either end, though the choice of design was left to the builder or owner. Requirements which were to be revised in later.
The RCH specified only the base requirements, builders were allowed a free hand in the detail design of the parts required to meet the standard.. This led to RCH 1887 wagons from the major builders having recognisably individual features, ranging from the design of axleboxes and brake pivot brackets to the design of door hinges and latches. While each builder had their own preferences they were now expected to adhere to or improve upon the defined standard.
The basic RCH 1887 mineral wagon design had internal measurements of 14ft 6in long by 7ft width. Minimum sizes of all underframe timbers were specified, along with side planking of 2½in thickness, giving a length over headstocks measurement of 14ft 11in and width over sheeting of 7ft 5in. A maximum width of 8 feet was allowable to accommodate fittings like hinges and door catches.
Dumb or dead buffers were still permitted, such buffers being formed as extensions of the side solebars and which in part restricted the width of the wagon, but the use of sprung buffers was promoted for the 'standard' wagon. Builders found it convenient to use longer timbers for headstocks to accommodate iron reinforcing brackets and the sprung buffer guide castings. By the time of the next major revision of the RCH standard in 1907 the headstock timbers were commonly 7ft 11in width with the additional width providing for an internal width of 7ft 6in.
Sprung buffers and draw hooks were the preference of the railway companies and the RCH, with the intent that dumb buffered wagons should be eliminated as quickly as practicable. The 1887 design featured a leaf spring behind the end headstocks with the ends resting against the tails of the buffer spindles and connected at its centre to the coupling hook. Thus one spring each end provided springing for the coupling hook and buffers, plus spreading the haulage loads from the central coupling hook to the headstock beam much closer to the solebars, thereby reducing the strain on the headstock timbers.
Below the solebars axles were to be manufactured from defined material types with journal centres at 6ft 6in spacing and wheels to have appropriately secured tyres, trying to control the risk of wheels shedding tyres. The axles were to run in suitable sprung axleboxes set in iron guides known as W irons from the shape of the vertical central guide slot between angled stiffening braces, with the axle centres set at 9 feet, a wheelbase which was to remain standard for mineral wagons until the 1960s.
Sides could be of 5, 6 or 7 planks height normally giving a capacity of 8, 10 or 12 tons of coal with 6½in planks, though plank widths could be varied and the height of the sides could be altered to suit the intended load. Some loads required additional capacity to achieve the intended full load weight, so coke rails could be added to provide a greater enclosed volume. Similarly wagons for aggregate and stone traffic were built with lower sides to prevent overloading. The wagons could be built with side, end and bottom (drop) doors as required by the owners. 5 plank wagons had side doors reaching the top of the wagon which 6 and 7 plank wagons usually had a 5 plank door and one or two solid planks above which made the body stronger. Some builders offered a top flap door option to provide a full-height opening.
In general wagons with one end door, side doors both sides and drop doors in the floor were ordered by collieries, coal factors and large industrial users to provide the best flexibility for unloading. Local coal merchants often ordered smaller capacity wagons with just the side doors as they rarely had the ability to empty the wagon by tipping or into an under-track bunker.
Differences between 1887 wagons and later RCH wagons.
The 1907 RCH specification largely tidied-up changes which had been incorporated since 1887. Over headstocks length had been rounded up to 15 feet, with 18in buffers giving an over buffers length of 18 feet. Widths could vary a little, although 7ft11in over planking was almost universal. Drawings show a maximum allowable width over fittings of 8ft6in, with a note that only 8ft3in is allowable for wagons working to 'Bristol Channel Ports'. Sprung buffers were required and while draw hook springing could use either a leaf spring which also acted on the buffer spindles the draw bars from both ends had to extend into a central box, aimed at creating a continuous drawbar and relieving the wagon timbers and fixings from pulling forces. 'Self contained' buffers were now an alternative, with coil or volute springs either in the buffer housing (making a larger diameter buffer housing) or fitted behind the headstock (using the thin bodied spindle buffers). Many dumb buffered wagons were 'converted' to conform to post-1907 standards, being rebuilt with the thicker bodied self-contained buffers and new drawgear.
At the 1922 grouping a new standard was issued, producing the RCH 1923 wagon. This is a much broader specification covering many variations, some of which were less than successful! The equivalent to the 1907 wagon was now 16ft6in long over headstocks and steel was being suggested for the main chassis members. Through drawgear was now mandated, the drawbars being extended into a frame fitted in the centre of the wagon and connected to it, and thereby the wagon, by volute springs. Oil lubricated axleboxes were specified, these previously being an option with added cost, but ran much more freely than grease lubricated boxes and usually needed much less maintenance.
The 8 ton wagon had disappeared, the lower capacity now being 10 tons for a 5 plank wagon and standard 12 tons for 7 or 8 plank height. Later many of these wagons were uprated to 13 tons capacity. The LMS and LNER both selected a standard RCH design as their standard mineral wagon, building several thousand examples, with the SR ordering a small number for their requirements for the Kent coal field. A 16 ton wagon with a 17ft6in wood frame appeared in the folio but this proved to be a weak design, with LNER and Gloucester built wagons built on this frame quickly developing hogged backs, though similar LMS built wagons did not seem to suffer this fate.
After 1923 the railway companies steadily adopted the RCH steel underframe as the standard basis for their wagon fleets which, through further developments and strengthening, served as the chassis for British Railways standard design wagons of the 1950s. Typically 'traffic' wagons, both open wagons and covered vans used the 17ft 6in version with first 9ft and later 10ft wheelbase, while the 250,000 BR 16-ton steel minerals retained the RCH mineral wagon size 16ft6in length 9ft wheelbase steel frame.