NCCER Heavy Equipment key terms

An individual designated by the employer who, through training and experience, can identify existing and predictable hazards in the work area and has authority to take prompt corrective action to eliminate them.

A worker assigned to guide an operator who cannot see the full path of travel or the load, using hand signals or radio to keep people and property clear of the machine.

A climbing technique for mounting or leaving equipment in which two hands and one foot, or two feet and one hand, stay in contact with the machine at all times to prevent falls.

A procedure for isolating energy sources on a machine before repair or maintenance, using locks and warning tags so the equipment cannot be started or released unexpectedly.

Rollover Protective Structure: a reinforced frame or cab built into a machine that protects the operator in a rollover, and which works only when the seat belt is worn.

A systematic visual inspection performed before each shift, checking fluid levels, leaks, tires or tracks, guards, lights, and safety devices, with defects corrected before the machine is operated.

A gauge that records total engine-running time; it is used to schedule maintenance intervals and track machine use instead of relying on calendar dates or road mileage.

Scheduled servicing, including lubrication, filter and fluid changes, and inspections at set intervals, done to keep equipment reliable, catch wear early, and avoid unexpected breakdowns on the job.

A standard agreed motion of the hand or arm used to direct an operator when voice or radio communication is not possible; only one designated signal person should direct the machine.

The circular area swept by the upper structure, counterweight, or attachment of a rotating machine; it must be barricaded or kept clear because the operator's rear and side view is limited.

The point at which a machine's weight is balanced; raising a load, extending the boom, or working on a slope shifts it and can cause tipping if it moves outside the machine's stability base.

A hydraulically extended leg with a pad that widens a machine's support base and transfers weight into the ground so it stays stable while lifting, digging, or working over the side.

A cubic yard of soil measured in its natural, undisturbed condition in the ground before loosening; it is the basis for comparing cut quantities with hauled and compacted volumes.

The percentage increase in volume when soil is excavated and broken up; loosened material takes more space than it did in place, so haul volumes are larger than cut volumes.

The reduction in volume that occurs when loose soil is placed and compacted into a fill; compacted fill occupies less space than the same soil did in its loose state.

The steepest slope at which a given loose material will stand without sliding; it varies with moisture and particle shape and governs how high spoil piles and slopes can safely be built.

The grouping of soil by particle size, strength, and stability, such as cohesive clay, granular sand, or rock, which determines the protective system and slope allowed in an excavation.

The water content at which a given soil reaches its greatest density under a specific compactive effort; soil that is too wet or too dry will not compact to the required density.

Mechanical densification of soil by rolling, vibrating, or tamping to remove air voids; it increases bearing strength and reduces settling and is checked against a required percentage of maximum density.

Any man-made cut, cavity, trench, or depression in the earth's surface formed by removing soil or rock; a trench is a specialized narrow excavation deeper than it is wide.

A narrow excavation below the ground surface that is deeper than it is wide, generally no wider than fifteen feet at the bottom, and one of the most hazardous excavations because of cave-in risk.

Excavated material temporarily piled beside a cut; it must be set back at least two feet from the edge of an excavation so its weight does not surcharge the wall and cause a collapse.

A support system of posts, beams, and sheeting installed inside an excavation to hold the walls in place and prevent soil from moving or caving in on workers.

A prefabricated shield of steel or aluminum plates joined by spreader bars that is lowered into a trench to protect workers from wall collapse and moved forward as the trench advances.

Cutting the sides of an excavation back at an angle shallow enough to prevent collapse; the required angle depends on the soil classification and is measured from the horizontal.

Cutting the sides of an excavation into a series of stepped horizontal levels, each with a vertical face, so soil is prevented from sliding into the work area below.

The process of having underground utilities marked by the one-call service and then verified before digging, so buried gas, electric, water, and communication lines are not struck.

A fixed point of known elevation, often a brass disk or permanent marker, from which all other elevations on a project are measured and checked during construction.

The vertical distance of a point above or below a stated reference plane, usually mean sea level or a project datum, expressed in feet or meters.

The earthwork balance of removing soil from high areas (cut) and placing it in low areas (fill) to reach the planned grade, ideally with the two volumes matching on site.

The native or compacted soil layer beneath a road, slab, or fill that supports the structure above; it must be prepared, drained, and compacted to the specified density.

A marker set beyond the edge of construction that shows the cut or fill needed to bring the ground to the planned slope or grade at that location.

A tracked machine with a front-mounted blade used to push soil, clear vegetation, and spread fill; it works best on short pushes and can rip hard ground when fitted with a rear ripper.

A heavy shank with a replaceable tooth mounted on the rear of a dozer or drawn behind a machine, used to break up rock, hardpan, or compacted layers before excavation.

A machine with a front bucket on lift arms used to dig, scoop, and carry loose material and to load trucks; wheel loaders travel faster, while track loaders work better in soft ground.

A machine with a bowl that cuts, loads, hauls, and dumps soil in a single cycle; self-propelled scrapers are efficient for moving large volumes moderate distances over prepared haul roads.

A wheeled machine with a long adjustable blade used to shape and level subgrade, cut ditches, and maintain haul roads; the blade can be angled, tilted, and offset.

A tracked or wheeled machine with a boom, stick, and bucket that digs by pulling toward itself and swings to dump; it is the most versatile machine for trenching and mass excavation.

A machine with a digging arm mounted on the rear of a tractor or loader that digs toward the operator and dumps by swinging, while the front bucket handles loading and backfilling.