Concrete Roads
and Their Construction

MECHANICAL DEVICES FOR MAKING ROADS 147 Elevators are particularly useful for lifting the road-materials from the ground level to trucks, etc., and where sufficiently large quantities are involved. Their use is much cheaper than that of hand-shovels. These elevators consist essentially of an end- less band or its equivalent, on which is mounted a series of slats or buckets which carry the material. If the height to which the material is to be lifted is not great, a plain band-conveyor will suffice, but for greater angles of elevation buckets are preferable. A self-contained wagon loader, supplied by Messrs. Winget, Ltd. (Fig. 97), will fill a 3-ton lorry in twelve minutes. It is specially designed for filling trucks and wagons with sand, gravel, crushed stone and similar materials, and is driven by a 2|-h.p. petrol or benzol engine, or, if desired, by electric motor. The belt-conveyor made by the Hepburn Conveyor Co., Ltd., Wakefield, shown in Fig. 87, is equally useful where an elevator of this type can be used. The addition of two rotary discs (as in the loader supplied by the Allied Machinery Co.) (Fig. 96), converts a bucket elevator into a self-feeding machine and so greatly enhances its value in road-making. The two horizontal steel discs set close to the ground revolve inwards towards the conveyor. Transporting the Materials.—The raw materials, consisting of stone or gravel, sand and cement, are usually brought to the roadway in motor-lorries, wagons or carts. Where the materials must be dumped in the roadway, these should preferably be of the self- tipping type, so as to reduce to a minimum the labour required in emptying them. Among the large number of tipping wagons available the “ Constable ” Patent Side-Tipping Wagons (Fig. 100) of Messrs. Tuke & Bell, Ltd., may be mentioned. During the operation of tipping, an angle of 50 degrees is obtained, which is sufficient to eject any class of material. The door on the side of the body automatically remains in its normal position and out of the way of the material being tipped. The load is discharged in 90 seconds. The material tipped on the side may be transported in wagons orcarts; or an automatic feeder and conveyor system, such as the Barber-Greene Loader (Fig. 96) may be employed for this pur- pose,