transport machines which move without using rail tracks. Trackless transport includes vehicles equipped with rubberized wheels (for the most part, pneumatic tires) that carry out the periodic transport of freight according to a fixed cycle. In-shop trackless transport moves freight (stock, raw material, semifinished goods, and finished products) within shops and warehouses, as well as in loading-unloading areas. In-plant trackless transport hauls freight between the main and auxiliary shops, warehouses, and loading and unloading points within the territory of enterprises. In the mining industry trackless transport moves freight through underground mines as well as on the surface of shafts and mines. The rolling stock of trackless transport includes hand trucks and self-powered trucks, freight motor scooters, tractor-trailers, and other carriers. Such trucks are employed for relatively light freight flows with a complicated route, when other types of transport would be uneconomical; they are suitable for use in narrow corridors and passageways. Hand trucks haul lightweight loads over short distances (usually up to 30–50 m); in order to faciliate the loading and unloading of materials, they may have lifting platforms. Depending on their type of motor, self-powered trucks are divided into those powered by electricity (storage battery, trolley, and high frequency [trucks with electromechanical converters providing a high-frequency supply for an AC motor]), by pneumatic means, and by internal combustion engines; this last category includes automobiles and motorcycles. The load capacity of such trucks is as high as 5 tons, and their speed ranges up to 20 km per hour; their body or platform may be equipped with a lifting apparatus. Widely used in industry are battery-powered electric trucks, which are quiet, simple to drive, and economical, as well as automotive and motorcycle trucks, which are more independent than the electric trucks and do not require time for recharging or changing batteries. The use of automotive and motorcycle trucks in closed areas is limited because of their noise and emission of harmful gases. To transport mail, baggage, and other goods at ports, railroad stations, and airports, self-powered trackless trucks are used, as well as freight motor scooters with a load capacity ranging from 150 to 1,000 kg, forklift trucks, and electric lift trucks.
For heavy-duty freight flows, tractors are employed to haul one or more unpowered trucks (trailers). The speed of various tractor models ranges from 2 to 40 km per hr, and their tractive force from 0.8 to 30 kilonewtons (80 to 3,000 kg). Their small dimensions, good maneuverability, and high tractive force allow tractors to be used within plant shops as well as at open-pit mining excavations (for example, in the form of trackless [motor-vehicle] trains), as well as in agriculture (tractors), at railroad stations, and at ports.
Specialized trackless transport is used in industry and construction for hauling unit and bulk freight.
At ore mines and coal mines, in earth moving, and for other operations, great amounts of various materials are hauled by dump trucks, earthmovers, and diesel-trolley trucks. The freight-hauling capacity of dump trucks may reach as high as 100–110 tons, and that of trailers up to 200 tons. Diesel-trolley trucks operating on permanent roads are powered from contact networks; on temporary routes they are powered from their own diesel generators.
In a number of countries (the USSR, Great Britain, the USA, West Germany) remote-control systems and automation of trackless transport operations have been developed. For example, electric tractors have been created with electronic control, which with the aid of a programming apparatus can carry out a practically limitless number of routes and stops.