GANTRY— (1) An overhead structure that supports
machines or operating parts. (2) An upward
extension of the revolving frame of a crane that
holds the boom line sheaves.
GEAR— A toothed wheel, cone, or bar.
GOOSENECK— An arched connection, usually
between a tractor and a trailer.
GRADE— (1) Usually the elevation of a real or planned
surface. (2) Also means surface slope.
GRADER— A machine with a centrally located blade
that can be angled to cast to either side with an
independent hoist control on each side.
GRADE STAKE— A stake indicating the amount of cut
or fill required to bring the ground to a specified
level.
GRAVEL— (1) Rock fragments from 2mm to 64 mm
(.08 to 2.5 inches) in diameter. (2) A mixture of such
gravel with sand, cobbles, boulders, and not over 15
percent fines.
GRIEF STEM— See “KELLY.”
GRIZZLY— (1) A coarse screen used to remove oversize
pieces from earth or blasted rock. (Maybe spelled
“grizzlie.”) (2) A gate or closure on a chute.
GROUND PRESSURE— The weight of a machine,
divided by the area in square inches of the ground
directly supporting it.
GROUSER— Projecting lug(s) attached to or integral
with the ma chine track shoes to provide additional
tract ion.
GRUBBING— Digging out roots.
HAND LEVEL— A sighting level that does not have a
tripod, base, or telescope.
HARDPAN— (1) Hard, tight soil. (2) A hard layer that
may form just below plow depth on cultivated land.
HAUL DISTANCE— (1) Is the distance measured along
the center line or most direct practical route between
the center of the mass of excavation and the center
of mass of the fill as finally placed. (2) It is the
distance the material is moved.
HOLDING LINE— The cable reeved from a hoist drum
for holding a clamshell bucket or grapple suspended
during dumping and lowering operations.
HOOK, PINTLE— A towing bracket, having a fixed
lower part and a hinged upper one, which, when
locked together, makes a round opening.
HOPPER— A storage bin or a funnel that is loaded from
the top and discharges through a door or chute in the
bottom.
HORSEPOWER— (1) A measurement of power that
includes the factors of force and speed. (2) The force
required to lift 33,000 pounds 1 foot in 1 minute.
HORSEPOWER, DRAWBAR— Horsepower available
to move a tractor and its load after deducting losses
in the power train.
HOLDING LINE— The hoist cable for a clamshell
bucket.
IDLER— Large end roller of a track assembly at the
opposite end from the drive sprocket; the roller is
not power-driven.
INJECTOR— In a diesel engine, the unit that sprays fuel
into the combustion chamber.
JACK— (1) A mechanical or hydraulic lifting device. (2)
A hydraulic ram or cylinder.
JACKKNIFE— A tractor and trailer in such an angle that
the tractor cannot move forward.
JAW— (1) In a clutch, one of a pair of toothed rings, the
teeth of which face each other. (2) In a crusher, one
of a pair of nearly flat faces separated by a
wedge-shaped opening.
JIB BOOM— An extension piece, hinged to the upper
end of a crane boom.
KELLY— A square or fluted pipe which is turned by a
drill rotary table, while it is free to move up and
down in the table. Also called a “GRIEF STEM.”
LAGGINGS— Removable and interchangeable drum
spool shells for changing the hoist drum diameter to
provide variation in rope speeds and line pulls.
LAY— The direction of twist in wires and strands in wire
rope.
LAY, REGULAR— A wire rope construction in which
the direction of twist of the wires in the strands is
opposite to that of the strands in the rope.
LEVEL— To make level or to cause to conform to a
specified grade.
LIFT— A layer or course of paving material, applied to
a base or a previous layer.
LIP— The cutting edge of a bucket. Applied chiefly to
edges including tooth sockets.
LOAD BINDER— A lever that pulls two grab hooks
together and holds them by locking over the center.
AI-5
