MOTOR TRUCK, a heavy type of auto mobile developed for carrying truck or freight. At first they were called auto-trucks, and were simply stout automobiles, with wagon bodies, suiting them to carry goods. Because of the great weight on the rear tires these were doubled literally, two tires being placed on each rear wheel. For a few years truck-builders gave their attention mainly to bodies, building them to suit all sorts of trades, but employing a cheap heavy automobile chassis and motor. As the automobile proper was improved for speed, it became less suited to use for a truck, where slow speed and large carrying capacity were demanded. Heavy, slow-running motors were then designed, but the old chain-drive for the rear wheels was adhered to. Though this chain was called °silent° it was a noisy affair, and the entire motor truck of that date (about 1910) looks very crude now. In 1914 and 1915 the war demand for motor trucks aroused American builders to construct more efficient models, and the result is that in 1918 there are on the American market well over 100 makes of motor trucks, that wholly outclass the older types. The great majority run from one to six tons. A light delivery wagon sells for $885; stout PA-ton trucks from $1.400 up; 2 to 3-ton trucks for from $1 775 to $3,250; 5- to 6-ton trucks for $3,750 to $5,500. These figures are taken from the listings at the automobile show in New York city in 1918. A few 7- to 10-ton trucks are being built. For motors the four-cylinder is most common, though many six-cylinders are employed. There is no de mand for a large number of cylinders, as in automobile and aviation motors. The typical motor-truck motor is often called an ((engine by the trade, because its design resembles small stationary and marine engines. Practice as to clutches varies, but the disc type predominates, this being well adapted to the slow speeds and heavy power transmission of the truck, though poorly adapted to a racing automobile. Roller bearings are universal, Tinkum and Hyatt being the familiar types. The chain drive has almost wholly given way to the improved worm drive, described and illustrated under automobile (q.v.). The four-wheel drive is increasing in
Popularity and numbers. Wheel bases tend to grow greater. The shortest seen on any 1918 truck was 124 inches on a small truck and 135 on a 6-ton truck, while the larger trucks of the best makes ran up to 163 to 180 inches wheel base.
The number of motor trucks in use in the United States in January 1918 was estimated by the editor of Motor to be 435,00U. The number of commercial cars built in 1917 was 181,348, but these are not all properly desig nated as motor trucks, for many of them are light wagons for city express work. The light traffic is being taken care of in large measure by an attachment to the Ford car. A truck frame and rear wheels are arranged to be hitched on to the fore-wheels and motor of a Ford car; any sort of a wagon body can be placed on top. This combination has a carry ing capacity of PA tons, utilizes heavy artillery wheels, 34 x including solid tires. The wheel base is 128, the loading space over nine feet long, and it sells for only $390 ready to attach to any Ford. This cheap truck is rap idly driving out the horse, and the estimate is that 2,000,000 horses have at this date (1918) been released from servitude in the United States by the near half-million of motor trucks in use.
The wonderful tests to which motor trucks were subjected in the Great World War have been a prominent factor in the development of superior machines. Manufacturers have met the strain and built better than they ever built before, producing machines that stood amazing rough usage, on broken ground, in the rear of the Allied armies. The demands of the Brit ish and American governments for certain types developed the artillery type of truck, adapted to army conditions. Thousands of these machines were built in the West, and made their way to the Atlantic seaboard for shipment under their own power. On several occasions the great Lincoln highway witnessed processions of them miles in length, all going over to help win the war.