Volume Thirteen - Pre-Victorian to the Present Day - even more aspects -1883 - Taff Vale Railway - Wagon Rules & Regulations . . . .

The boss, if cast-iron, to be not less than thirteen inches diameter by seven and a half inches wide, if wrought-iron, to be not less than nine and three-quarters by seven inches wide. The wheels to be forced onto to the axles by hydraulic pressure of not less than forty-six tons.

The tyres to be made of the best quality Bessemer steel, or best wrought-iron of approved manufacture, rolled solid, and not welded. Each tyre to be truly turned in a lathe, and when finished, to be three feet in diameter, and five inches wide, and, for new wagons, not less than two inches thick in centre of thread. The distance from back to back of tyres to be four feet five and a half inches.

No tyre will be allowed to run if it be at any part less than one inch and one-eighth in thickness, or if one tyre differs in diameter to the other on the same axle.

The axles, of sizes specified hereafter, to be made of best mild Bessemer steel, or of the Patent Shaft and Axletree Co.'s doubled fagotted iron, all of approved manufacture.

"Doubled fagotted iron" was a specific, high-quality manufacturing process used, by the Patent Shaft and Axletree Company of Wednesbury in the Midlands, to create railway and coach axles of superior strength and reliability. The term describes a method where a central iron bar was surrounded by smaller, rounded iron bars to form a bundle, known as a "faggot". This bundle was then heated and welded together under a hammer. The process was repeated ("doubled") to ensure the complete welding of all components and to produce a uniform grain structure throughout the resulting axle. The key innovation of this process, invented around 1830 by James Hardy, was the use of rounded outer bars instead of the flat strips used previously. This design prevented "cross graining" of the iron during the forging process, which had been a common cause of failure in earlier axles. The resulting product was an axle of equal strength throughout its entire length, highly suited to the demanding requirements of the burgeoning railway industry.

Each wheel to be keyed to the axle with a flat wrought iron key not less than seven-eights of an inch wide, and five-eighths of an inch, properly tapered and well fitted.

All tyres and axles to be branded with the maker's name, quality, and date of manufacture, and every part guaranteed to be of best quality.