Construction Plant Fitting key terms

Powered machinery and equipment used on construction sites to excavate, lift, compact, mix, or move materials, such as excavators, cranes, rollers, and concrete pumps.

A skilled tradesperson who assembles, installs, maintains, troubleshoots, and repairs construction machinery, working with mechanical, hydraulic, pneumatic, and electrical systems on site or in a workshop.

Heavy machines that dig, load, haul, or level soil and rock, including excavators, bulldozers, wheel loaders, backhoes, and dump trucks used in groundworks.

A tracked or wheeled digging machine powered by a diesel engine driving hydraulic pumps that operate boom, arm, bucket, and travel circuits through control valves.

The lower running gear of a tracked machine, comprising track chains, track shoes, rollers, idlers, sprockets, and track frame, which carries the machine and absorbs ground loads.

The correct slack adjustment of a crawler track chain; too tight accelerates wear on pins and sprockets, while too loose allows derailment, so it is set per the manufacturer's measurement procedure.

The toothed drive wheel at the rear of a crawler undercarriage that engages the track chain and transmits drive torque from the final drive to move the machine.

The last gear reduction assembly, often a planetary hub or hydraulic travel motor, that converts engine or motor speed into high torque at the wheels or track sprockets.

A closed or open loop of pump, valves, actuators, reservoir, filters, and pipework through which pressurized fluid transmits force and motion to machine components.

A device that converts mechanical drive power into fluid flow and pressure; common construction plant types are gear, vane, and variable-displacement axial piston pumps.

A pressure-limiting valve that opens to divert fluid to tank when circuit pressure exceeds a set value, protecting components such as pumps, hoses, and cylinders from overload damage.

A linear actuator in which pressurized fluid acts on a piston to extend or retract a rod, producing the push or pull force used for booms, arms, outriggers, and blades.

A rotary actuator driven by pressurized fluid that produces torque and rotation, used for travel drives, slew drives, winches, and cooling fan drives on plant.

Oil that transmits power, lubricates internal parts, and carries away heat and contaminants in a hydraulic system; its viscosity grade and cleanliness must meet the machine specification.

A component that removes particles from hydraulic oil, protecting pumps, valves, and actuators; it is replaced on schedule and checked for bypass or restriction indicators.

The practices of sealing openings, cleaning around fittings, filtering oil, and monitoring particle counts to keep hydraulic and fuel systems free of dirt, water, and debris.

The process of purging trapped air from a hydraulic circuit or fuel line after assembly or repair, so that components respond correctly and pumps do not cavitate or run dry.

A ring, lip seal, or O-ring that prevents internal and external leakage of hydraulic fluid past pistons, rods, and joints while allowing movement; damaged seals cause loss of pressure.

A network of compressor, receiver, valves, filters, lubricators, and cylinders that uses compressed air to operate brakes, clutches, and tools on construction plant.

A machine that draws in air and compresses it for storage in a receiver or direct use, supplying pneumatic circuits and tools; it requires cooling, filtration, and pressure control.

A compression-ignition internal combustion engine widely used in construction plant, where fuel is injected into highly compressed hot air and ignites without a spark plug.

The metered delivery of diesel fuel under high pressure into the combustion chamber at the correct time and quantity, controlled by a pump, injectors, and electronic unit.

The radiator, water pump, thermostat, fan, and coolant circuit that remove engine heat; overheating is a common plant fault caused by low coolant, blocked radiator, or failed thermostat.

The oil pump, filter, galleries, and sump that supply clean oil to engine and machine bearings and moving parts, reducing friction and wear; oil pressure is a key health indicator.

Scheduled inspection, servicing, lubrication, adjustment, and replacement of wear parts carried out at defined intervals to avoid breakdowns and extend machine service life.

Using measurements such as oil analysis, vibration, temperature, and pressure to track machine health and detect developing faults before they cause failure or unplanned downtime.

Laboratory testing of lubricant samples for wear metals, contaminants, and fluid condition, used to schedule repairs and judge component wear without dismantling the machine.

Measuring and interpreting machine vibration signatures to identify imbalance, misalignment, loose mountings, or bearing defects before they escalate into breakdowns.

A systematic process of gathering symptoms, testing circuits and components, and eliminating causes to identify why a machine or system is not operating correctly.

The practical step-by-step procedure of locating and correcting a malfunction, typically working from the operator report through checks of power, fluid, and control circuits.

A test instrument combining voltmeter, ammeter, and ohmmeter functions, used to check electrical supply, continuity, resistance, and sensor signals on plant electrical systems.

An instrument that displays fluid or gas pressure so a fitter can verify pump output, relief valve settings, and circuit performance against the manufacturer's specified values.

A drawing showing electrical components and their connections by symbol and wire number, used to trace circuits, locate faults, and confirm correct reconnection after repair.

The manufacturer's document giving specifications, torque values, adjustment procedures, and maintenance schedules for a machine; it is the primary reference for correct repair work.

A calibrated wrench that indicates applied turning force, used to tighten fasteners such as cylinder head bolts and structural joints to the specified value and sequence.

A component that supports a rotating shaft and reduces friction, such as a roller, ball, or plain bearing; correct fit, lubrication, and alignment determine its service life.

A large geared bearing that connects the upper structure of an excavator or crane to its undercarriage, allowing it to rotate; it requires lubrication and bolt torque checks.

A retractable hydraulically or mechanically extended leg that stabilizes cranes, concrete pumps, and mobile plant by spreading load to the ground during lifting or operation.

The maximum load a machine, lifting accessory, or sling may safely carry under stated conditions, determined by the manufacturer and marked on the equipment or load chart.

Equipment used between the crane hook and the load, such as slings, shackles, chains, and lifting beams, which must be inspected, rated, and used within their marked capacity.

A planned activity of raising, moving, and lowering a load by crane or hoist, requiring a lift plan, competent personnel, exclusion zones, and inspection of all lifting equipment.

A documented process of identifying hazards, judging the likelihood and severity of harm, and recording control measures before work such as plant repair or lifting begins.

A safety procedure that isolates energy sources, applies locks and warning tags, and verifies zero energy before maintenance so machinery cannot start or release stored pressure unexpectedly.

A formal written authorization controlling high-risk tasks, recording the scope, hazards, isolations, and precautions, and requiring sign-off before work starts and on completion.

Energy held in raised components, compressed springs, pressurized accumulators or hoses, and charged batteries that can cause injury unless released or restrained before work.

Maintenance organized in advance from schedules and inspections, including preventive and predictive work, so that servicing is carried out before failure rather than after breakdown.

The operating hours or calendar period at which specified maintenance tasks, such as oil changes, filter replacement, and inspections, must be performed on a machine.