LOADER, FRONT-END A tractor loader that both
digs and dumps in front.
LOAM A soft easily worked soil, containing sand, silt,
LOOSE YARDS Measurement of soil or rock after it
has been loosened by digging or blasting.
LOW BED A machinery trailer with a low deck.
LUFFING Operation of changing the boom angle in
the vertical plane. See BOOM HOIST.
LUG DOWN To slow down an engine by increasing
its load beyond its capacity.
MASS DIAGRAM A plotting of cumulative cuts and
fills, used for engineering computation of
MINERAL DUST The portion of the fine aggregate
passing the 0.075-mm (No. 200) sieve.
MINERAL FILLER A finely divided mineral
product, at least 70 percent or which will pass a
0.075-mm (No. 200) sieve. Pulverized limestone is
the most commonly manufactured filler, although
other stone dust, hydrated lime, portland cement,
and certain natural deposits of finely divided
mineral matter are also used.
MISFIRE Failure of all or part of an explosive charge
to go off.
MOLDBOARD A curved surface of a plow, dozer
blade, grader blade, or other dirt-moving implement
that gives dirt moving over it a rotary, spiral, or
MUCK Mud rich in humus.
OIL Any fluid lubricant, but not water.
OPEN-GRADED ASPHALT FRICTION
COURSE A pavement surface course that consists
of high-void, asphalt plant mix that permits rapid
drainage of rainwater through the course and out the
shoulder. The mixture is characterized by a large
percentage of one-sized coarse aggregate. This
course prevents tire hydroplaning and provides a
skid-resistant pavement surface.
OSCILLATION Independent movement through a
limited range, usually on a hinge.
OUTRIGGER An outward extension of a frame that
is supported by a jack or block, used to increase
OVERBURDEN Soil or rock lying on top of a pay
PAN A carrying scraper.
PAWL A tooth or set of teeth, designed to lock against
PENETRATION The consistency of a bituminous
material expressed as a distance in tenths of a
millimeter (0.1mm) that a standard needle
penetrates vertically a sample of the material under
specified conditions of loading, time, and
PERCENT OF GRADE Measurement of slope,
expressed as the ratio of the change in vertical
distance (rise) to the change in horizontal distance
(run) multiplied by 100.
PETCOCK A small drain valve.
PILE CAP An adapter between the pile-driving unit
and the upper end of the pile, used to center the pile
under the pile-driving unit and to reduce damage to
the upper end of the pile.
PIONEERING The first working over of rough or
PIONEER ROAD A primitive, temporary road built
along the route of a job to provide means for moving
equipment and men.
POND A small lake.
PORT Left side of a ship or boat.
POTHOLE A small steel-sided hole caused by traffic
POWER EXTRACTOR A unit hanging from the
hoist line or block and attached to the upper end of
the pile and containing within itself a member (ram)
which is caused to reciprocate either by means of
externally supplied air, steam, or hydraulic fluid
under pressure, or by internal combustion within the
unit. Upward pull from the hoisting machinery
supplements the extraction forces.
POWER PLANT The power plant (or plants) includes
the prime power source (which may be an internal
combustion engine or electric motor) and the power
POWER TAKEOFF A place in a transmission or
engine to which a shaft can be so attached as to drive
an outside mechanism. A power takeoff may be
direct drive, friction clutch, fluid coupling,