In 1844 r. W. Prosser obtained a patent for "Improvements in the construction of railways and in carriages to run thereon;" the latter improvement consisting in the removal of the guiding flanges from the periphery of the bearing wheels, and substituting for them a peculiar arrangement of guide wheels attached to the frame of the carriage. These guide wheels were devised chiefly with reference to Mr. Prosser's improvements in the construction of railways, in which he proposed to substitute for the iron rails, continuous bearings of solid Kyanised timber.
But as these guide wheels are applicable on railways of the ordinary construction, and as the arrangement appears to exhibit considerable ingenuity, and to possess much practical merit, we subjoin a short description of it. We may observe that the idea of employing guide wheels instead of flanges on the bearing wheels to keep the carriages on the rails is not new; indeed we have in the course of this treatise noticed several plans for this purpose, but we believe that by all previous arrangements a third or additional rail was required for the guides to act upon; whereas in Mr.Prosser's plan no additional rail is requisite as the guides act upon the bearing rails, and possess this great advantage, that in the event of breaking of an axle they would support the carriage and enable it to continue its course.
An end view of a locomotive with these guide wheels attached is given in the following engraving.
a a is the engine frame, b, b the bearing wheels, c, c the wooden longitudinal bearers before mentioned; but for which may be substituted the ordinary iron rails: d, d are the guide wheels turning upon pivots in a frame e attached to the end of the frame of the engine. These wheels are placed at an angle of 45° with the horizon, and have an angular groove in their periphery, one face of the groove being horizontal, or parallel to the surface of the rail, and the other face being vertical or parallel to the side of the rail. The distance between the guide wheels is a little less than the distance.between the rails, so that when the carriage is proceeding in a straight direction the guide wheels do not come in contact with the rails; but when the carriage deviates to one side, the guide wheels on that side are brought immediately into action, and prevent further deviation.
Mr. Prosser'g rails and wheels have, we believe, been adopted on the Guildford and some other lines of railway.