In the specification of a patent granted to Mr. Robt. Stephenson in 1831, he informs us that in the carriages previously used on the Manchester and Liverpool railway, each pair of wheels was fixed fast on the two opposite ends of a long solid axis, which revolved with the wheels, and the two extremities of the solid axis, which projected through the centres of the wheels, were formed into pivots or gudgeons and were received into suitable sockets, whereon the weight of the carriage was borne by the concavities of those sockets pressing downwards upon the pivots. In travelling with great rapidity, the said pivots required a copious supply of oil, and much of it was wasted, because the concavities of the sockets being inserted, the oil had a tendency to run down and escape from the places of bearing where it was wanted. According to the improvement of 1831, Mr. Stephenson's plan consists in fixing the pair of carriage wheels fast upon the extreme ends of a long hollow, or tubular axis, within which a solid central axis is inserted, extending through all the length of the hollow, and projecting out sufficiently beyond each of the hollow axes to enable the weight of the carriage to be supported upon the projecting ends of the solid central axis, around which the hollow axis turns, together with the two wheels, which are both fastened upon the ends of the hollow axis, to prevent one wheel from advancing either faster or slower along one rail than the other wheel advances along the other rail.
In the subjoined figures - Fig. 1 represents a vertical section through the centre of the wheel to show the novel arrangements of the parts, and Fig. 2 a side elevation of the same.
At a a a is the solid axis, enlarged at a; b is the tubular axis, passing through the central boss c of the wheel d d, and bolted to the same as shown at e e e e through a circular plate f front. The weight of the carriage is supported at gg on the projecting part of the axis a; which is received into a solid metal socket h, made in two halves, and screwed together by four bolts ii, and two staple boltsj j, which fasten the springs k down across the upper flat sides of the socket h; thus the two halves of the socket are bound firmly together by the said screws around the end g of the solid axis, and secures them together. The outer end of the socket h is fitted into a vertical groove formed in the space between the prongs of the guide plate l, which is screwed to the horizontal side rail m of the carriage, as shown in Fig. 1, and projects downward therefrom. The oil is supplied at an aperture o, provided with a screw plug, and finds its way between the rubbing surfaces of the axis, and the portion that escapes past the bearings is received into an oil box n of cast iron, made in two halves for fitting it on to its place.