a mechanical percussion-type hand tool used to separate soft rock from a mass, to loosen frozen soil, and to break up concrete foundations and asphalt and concrete paving.
The working member of a mechanical pick may be a slice bar, chisel, or shovel, depending on the type of work to be done and the characteristics of the mass to be broken up. The hammer head, which moves in the pick housing at a rate of 1,000–1,500 impacts per minute, delivers blows to the tail part of the tool; the energy of the impacts is used to perform work. Mechanical picks may be pneumatic, electric, or gasoline-powered (driven by a gasoline internal-combustion engine). Pneumatic energy (compressed air) is supplied to the mechanical pick from an air-supply system through a flexible hose; 127–220-volt electric power is supplied through a flexible cable from the mains through a step-down transformer or from a portable electric power unit. Internal-combustion engines (motors) and fuel tanks are usually built into the housing of the mechanical pick.
Pneumatic picks are most widely used, because of their small size and weight, considerable power, simplicity of design, and high dependability. Electric and gasoline-powered picks are almost never used in the USSR because of their great weight and low reliability.
Lightweight vibration-proofed mechanical picks, in which the harmful effect of the vibrations generated during their operation and transmitted to the hands of the worker is reduced to a level specified by health standards, were developed in the USSR in 1973.
Pneumatic pick hammers weigh about 7 kg without the working tool; the impact energy of a single blow is 38–45 joules (3.8–4.5 kg · m), and the flow rate of compressed air is 1.14–1.22 cu m per min.
V. G. ZHADAEV