Appearances would indicate that at no very distant date iron or steel will take a conspicuous part in the formation of future railway sleepers.
More than thirty years ago several descriptions of cast-iron sleepers were introduced into notice and tried on some of our leading home railways. Cast-iron was at that time considered more suitable for the purpose than wrought iron, as it was very much less costly in price, and could be readily worked into any desired form or size, with the advantage that the castings would all be duplicates of one another.
[Figs. 307 to 313] show some of the types that were designed and laid down in the road. In [Fig. 307] the sleeper and chairs were all cast together in one piece; the rail was held in its place by wooden keys, and the gauge of the line was maintained by transverse wrought-iron tie-bars. The sketch represents one of the sleepers used at the rail-joints, and has three chairs, the larger one in the centre being for the support of the ends of
the rails. This arrangement was the same as was then in use on the ordinary wood-sleeper road, where an extra large chair was placed at the rail-joints, and was the most approved method for many years before fish-plates were introduced. The intermediate sleepers were shorter, and had only two chairs.
[Fig. 30]8 represents a long, flat, cast-iron sleeper made in two halves, bolted together just below the under side of rail at each of the three chair-seats. The rail was gripped and held in position without the use of wooden keys. This being a joint sleeper, three chairs were used, as in [Fig. 307]. Only two chairs were used on the intermediate sleepers.
[Figs. 309 and 310] are somewhat similar, but the circular one is higher and more cup-shaped than the other of oval form. The oval pattern has two small recesses for holding two small hard-wood cushions. The circular holes shown in the sides of the sleepers were intended to facilitate the packing, or tamping, of the light sandy ballast.
[Fig. 311] represents a rectangular cast-iron sleeper, as used for the flange rail. The rail rests on cast-iron cross-ribs, bevelled to give the proper cant, and is held in position by the tie-bar bolt and clip-piece, as shown. The small projecting lug, formed on the under side of sleeper, fits into a corresponding notch in the tie-bar, and keeps the sleepers to gauge. The tie-bar passes through the loop end of the same bolt which secures the rail, and is held up tight against the under side of sleeper.
[Figs. 312 and 313], both the same in principle, possessed features which appeared to give great promise. They were simple in construction; the rail was kept well down, and did not come in contact with the cast-iron at any point. The long wooden wedges, which fitted into the rough or serrated sides of the casting, acted as a cushion to the rail, and were intended to sink deeper into the recess as the super-imposed weight increased, or the wood became thinner from shrinkage. In practice, however, it was found that these sleepers were not the success that was anticipated.