Clearance(redirected from occlusal clearance)
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the maximum profile of an object. As applied to transport vehicles and the moving parts of stationary machines, clearance is determined on the basis of their safe movement among other machines and structures. Outside the clearance, which permits the movement of machines in different directions, it is possible to erect structures and set up machines, lathes, and the safety zone for people. For example, the clearance of a moving train is the maximum profile in a plane perpendicular to the axis of the railway track beyond which no part of a locomotive or car should project when in working order. A railway clearance gauge is the maximum profile in a plane perpendicular to the axis of the railway track within which no parts of structures and equipment should extend. Meeting these clearances ensures the safe movement of trains in tunnels, on bridges, and under over-bridges. Underbridge clearance is the profile of the clear opening under a bridge between the bottom of its span structure and the estimated navigable level in height and between the supports of the span in width.
REFERENCESEvgrafov, G. K., and N. N. Bogdanov. Proektirovanie mostov. Moscow, 1966.
Evgrafov, G. K., and N. N. Bogdanov. Zheleznye dorogi. Moscow, 1968.
Evgrafov, G. K., and N. N. Bogdanov. AvtomobiV. Ekspluatatsiia i remont. Entsiklopedicheskii slovar’-spravochnik. Moscow, 1968.
I. A. IVANOV
the distance from ground level (plane of reference) to the lowest structural member of a motor vehicle, excluding the wheels; one of the parameters that determine the operational trafficability of motor vehicles.
The minimum permissible clearances established in the USSR are 200 mm, 240 mm, 260 mm, and 270 mm for fully loaded trucks with carrying capacities of 1.5 tons, 3 tons, 5 tons, and 8-12 tons, respectively, and 240-270 mm for buses, depending on their length and purpose.