In order to secure the axle more effectually than has hitherto been done, on the wheel, a new improvement has been invented by John Olles, of Philadelphia, who has taken measures to secure a patent. For this purpose two tubes, one inside the other, are let into the eye of the hub, and the end of the axle is made of a suitable shape to play freely within the inner one, but is prevented from working out by means of a collar and screw box, which are fitted on to the outer tube. The objects effected by this arrangement are, first, that of shifting the bearing of the axle to all parts of the inner circumference of the intermediate casing, which is accordingly made movable, and in the second place that of securing the wheel firmly on the axle as well as preventing the oil from flowing any where except to that part of the axle inside the hub.