Hoisting and Conveying Machines
Hoisting and Conveying Machines
equipment for vertical, horizontal, and inclined movement of freight and passengers. They are the principal means for the mechanization of loading and unloading work and hoisting and conveying operations in industry, construction, transportation, mining, and agriculture. They are also used to move people in high-rise residential, public, and administrative buildings and in mines and subway stations.
Hoisting and conveying machines may be arbitrarily divided into five large groups, depending on their purpose and the nature of the movements performed: (1) load-lifting machines and mechanisms, (2) conveying machines, (3) overhead monorail transport machines, (4) ground transport machines (including trackless transport), and (S) loading and unloading machines. Machines of all groups may operate intermittently or continuously. Among the intermittent-operation machines are the simplest unpowered hoisting devices, such as pulleys and blocks and tackles, as well as hoisting machines (mainly electric cranes, freight and passenger elevators, and hoists). Among the continuous-operation machines are various types of conveyors, including such passenger types as moving sidewalks; elevators; escalators; and paternosters. The monorail transport machines include electric and pneumatic types, overhead electric tractors, electric and other self-propelled trolleys. Ground transport machines include forklift trucks, electric loaders, and electric stackers. Loading and unloading machines may operate intermittently (single-bucket loaders, vehicle unloaders and car dumpers, inertial unloaders, and scraper unloaders) or continuously (mul-tibucket loaders, pneumatic unloaders, and unloader-stackers).
Hoisting and conveying machines may have electric, hydraulic, or pneumatic drive, or they may be powered by an internal-combustion engine. Applications are also being found for linear electric motors, mainly of the induction type, which make possible direct coupling between the motor and the machine, without an intermediate mechanical transmission.
Progress in hoisting and conveying machines is associated with the development of designs that are more reliable and have excellent technical parameters, while at the same time consuming less metal and power. Progress also involves the creation of groups of machines that combine the functions of intermittent-operation and continuous-operation machines, manipulators, and robot machines (machines with programmed control) that perform various operations in areas that are difficult of access or under conditions that are dangerous to human health. An example of a hoisting and conveying complex is an aerial cableway, which includes the mechanical and electrical equipment of the terminal and intermediate stations, as well as rails, the rolling stock (trolleys), the traction and supporting cables, the mechanical equipment of masts, and the structural works (the station buildings, masts, and protective bridges). The installations that form the basis of systems of conveyor (belt and cable-belt conveyors), aerial-cable, monorail and pneumatic-capsule transport are also complexes.
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Aleksandrov, M. P. Pod”emno-transportnye mashiny, 4th ed. Moscow, 1972.
V. S. KONOVALOV