In addition to the safety furnished by these containers they are economical in saving time of transportation. Re-handling is unnecessary. The transfer of the entire container from truck to car and from car to truck is very quickly made. The mileage of the flat cars is thus greatly increased--with mail cars it is claimed to be doubled. Expensive packing and crating is avoided and the checking at each rehandling of parcels is eliminated. Mass loading or unloading, whether the whole truck body is swung off by a crane, rolled off, or even if trailers and semi-trailers are left to be worked upon after the truck has gone, save little in the way of manual labor. On the other hand they require the installment at each end of the route of special arrangements to facilitate their use. Another class of devices are those connected with the truck itself. For example it may have a winch on it to draw up an inclined plane at its rear such heavy articles as pianos, safes, and large castings. It may have a crane with a pulley running along a central beam over it to facilitate loading and unloading heavy boxes or other things. A swinging crane is also used with some trucks. On others, hoists are arranged to tip the body backward for unloading building and road materials, grain, and so on. Many of these devices make use of the truck power for their operation. Pumps with suction hoses empty catch basins, cess-pools, stopped-up sewers and flooded cellars, pumping the fluid to a tank body of the truck, whence it can be hauled away and dumped by elevating the front end of the tank and opening a gate in its rear. Devices for lifting and dumping coal truck bodies directly into the bin save much time over hand shoveling. Still another class of devices are entirely separate from the truck and may or may not be connected with the warehouse. For example a chain conveyor which can be rolled up to the back of a truck elevates barrels and boxes, sand and stone, and is operated by a small electric motor the lead wires of which are plugged into a suitable socket, up to the floor at the rear of the truck from which place they can be easily pushed or shoveled to proper position. Elevated bins are utilized to store road materials from which the materials run by gravity into the body of a small motor-car which then goes to the mixer where it is grabbed by a device that empties the body into the mixer, thus saving much handling of material.