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
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.
COPEThe 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
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
GUY LINEThe 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
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
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
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.