Appendix I Glossary

APPENDIX I GLOSSARY BLOCK— One or more sheaves fitted in a wood or metal frame supported by a hook or shackle inserted in the strap of the block. BREECH— The part of the block opposite the swallow. BURR— The sharp edge remaining on metal after cutting. CHOKER— A chain or wire rope so fastened that it tightens on its load as it is pulled. COMPRESSION STRESSES— The stresses developed within a material when forces tend to compress or crush the material. COPE—The notch or shape to fit or conform to the shape of another member. DUCTILITY— The property that enables a material to withstand extensive permanent deformation due to tension. ELASTICITY— The ability of a material to return to its original form after deformation. FALL— A line reeved through a pair of blocks to form a tackle. FATIGUE— The tendency of a material to fail after repeated stressing at the same point. FATIGUE STRENGTH— The ability of a material to resist various kinds of rapidly alternating stresses. GUY LINE—The fiber line or wire rope used for holding a structure in position. IMPACT STRENGTH— The ability of a metal to resist suddenly applied loads; measured in foot-pounds of force. LAY— Refers to the direction in which wires are twisted into strands or strands into rope. LAYOUT— The process of measuring and marking materials for cutting, bending, drilling, or welding. MALLEABILITY— The property that enables a material to withstand permanent deformation caused by compression. MOUSING— technique often used to close the open section of a hook to keep slings, straps, and so on, from slipping off the hook. OVERHAUL— To Lenghten a tackle by pulling the two blocks apart. PLASTICITY— The ability of a material to per- manently deform without breaking or rupturing. ROUND IN— To bring the blocks of a tackle toward each other. SCAFFOLD— A temporary elevated platform used to support personnel and materials in the course of any type of construction work. SEIZE— To bind securely the end of a wire rope or strand with seizing wire. SHEARING STRESSES— The stresses developed within a material when external forces are applied along parallel lines in opposite directions. SNATCH BLOCK— A single sheave block made so the shell on one side opens to permit the line to be placed over the sheave. SHELTERING— TO attach a socket to wire rope by pouring hot zinc around it. STRESS— External or internal force applied to an object. SWALLOW— The opening in the block through which the line passes. TACKLE— An assembly of blocks and lines used to gain a mechanical advantage in lifting or pulling. TENSILE STRENGTH— The resistance to being pulled apart. TENSION STRESSES— The stresses developed when a material is subjected to a pulling load. TWO-BLOCKED— Both blocks of a tackle are as close together as they wilI go. ULTIMATE STRENGTH— The maximum strain that a material is capable of withstanding. WHIPPING— The process of securing the ends of a line to prevent the strands from unlaying or separating. AI- 1