In the early days of railway communication difficulties had to be encountered. The first lines were, for the greater part, communications between one point and another, for which comparatively straight courses could be taken. As they multiplied, and inter communication between the lines of different companies became established, and the country reticulated with main lines, the introduction of sharp curves became in many cases a necessity, the disadvantages of which, with a long wheel base and rigidly fixed rectangular axles, are obvious. Some of these difficulties most apparent, are increased fractional resistance, the continuous grinding abrasion of tyres and rails on curves, the straining of carriages from the forced and unnatural motion, the necessity for laying a double rail at sharp curves, and the expenditure of a large quantity of grease - a clumsy yet necessary expedient—upon the grooves formed by such fence rail, in which the tyres run. The effect of the abrading action in passing round curves is that the edge of the rail is rapidly worn, and the flange of the wheel ground off, necessitating that valuable unworn metal should be turned down upon the tyre so as to reproduce a flange.
The desiderata for carriages running upon curves are to a great extent supplied by Mr. James Cleminson, in his system of radiating axles for railway and tramway carriages and wagons. The cardinal merit of this system is that each pair of wheels in a vehicle adapt themselves automatically to the curve over which they pass, and the axle becomes a radius of the circle of which it forms part. This important object is attained by mounting the axles with their axle-boxes, guards, etc., in moveable frames, each pair of wheels and axle having their own frame. The end frames have central pivots, on which they work freely, and adapt themselves to the particular curve; the middle frame slides transversely, the whole of the axles by a simple self-acting process becoming true radii. The axle-frames are connected by articulated radiating gear; they give a bearing on their outer edges to the main frame of the carriage, so that the lengths in suspension are very short; and heavy scantlings and trussing in the framing are totally unnecessary, and the grinding action of the flanges upon the rails is entirely avoided.
Neues System beweglicher Radgestelle für Eisenbahnwagen und dazu gehörige Bremsvorrichtungen