Since some of our readers collect and restore road rollers, we present this information from a book, 'New Catechism of the Steam Engine,' M. E., published by Theo Audel & Co. in 1897 and 1904.
The steam road roller may be classed among portable engines.
It is built in various sizes, and can be used for rolling down highways, breaking up old roads, plowing and hauling heavy loads, etc.
Some road rollers have a boiler of the locomotive type; on these styles, the engine being a horizontal one, is placed on top of the boiler, and connected to the driving wheels or back rollers by means of sprockets and chain, or gear wheels.
In these rollers the boiler forms the principal part of the frame; the front of it, which forms the smoke box, as in the locomotive, is built out into 'the goose neck,' to which is swiveled the yoke by means of the king bolt.
The yoke being able to swing, rests upon the axle of the front roller, which also forms the steering wheel. The horizontal swinging motion is imparted to it by the steering mechanism, which consists of chain and worm gear, and is operated by a hand-wheel near the reversing lever. Figure 1 shows a roller of this type, which is built by the Harrisburg Car Mfg. Company of Harrisburg, Pennsylvania.
Other types are built with upright boiler and. engine. In this type of construction a heavy frame forms the body of the machine and is carried out into the 'goose neck' in front, which does not differ from the former one described, except the steering device being attached to the king bolt by means of a lever, is operated by a screen and nut. The back roller carries the rear end, and also, in this case, forms the driving wheel.
The boiler is nearly half way between the back and front roller, resting on the frame, and the engine is attached to it on one side. It is a double reversing engine, the crank shaft being connected to the back roller by means of bevel gear and pinion.
A roller of this type is shown in Figure 2, was constructed by the Erie Machine Shops located in Erie, Pennsylvania.
As will be seen in the illustration, the tank is placed above the back roller, almost surrounding it. In all road rollers, it is necessary, on account of unevenness of roads, to allow the front roller to swing in a vertical plane with its yoke; to accomplish this the king bolt is not directly fastened to the yoke, but has an eye on its lower end, through which a bolt passes, which suspends the yoke on it, and allows it to swing.
In case one side of the front roller should run over a stone, or any other obstruction, it is thus relieved; otherwise it would put a heavy strain on the king bolt, and might break it. This construction is plainly shown in both illustrations.
For breaking up old roads, the rear rollers in Figure 248 are provided with holes, into which pins are set, which are forced down into the road bed by the weight of the machine, and by the revolving of the wheels, break up the surface.