Equipment glossary: ratings, components and operating terms

Use the full measurement label and configuration when reading an equipment term. Bucket volume, lift capacity, vehicle ratings and tiedown working load limit describe different quantities. The definitions below distinguish those meanings and link to the relevant detailed checks.

Aggregate WLL: a connection changes the arithmetic

Under 49 CFR 393.106(d), four direct vehicle-to-cargo tiedowns rated 4700 lb each provide 4 × 4700 × 0.5 = 9400 lb aggregate credit. A 24000 lb article requires at least 12000 lb under that aggregate test, so four are insufficient. Six provide 14100 lb; the applicable count, attachment and other securement requirements still need checking.

Terms A–Z

Aggregate working load limit

The credited sum under the applicable securement rule, not always the full sum of device ratings. Under 49 CFR 393.106(d), direct vehicle-to-cargo and same-side arrangements receive half-WLL credit; a qualifying opposite-side arrangement receives full credit. See tiedown calculations.

Amplitude

The stated magnitude of vibratory drum motion. Check whether the specification uses single or double amplitude and retain the selected setting; amplitude alone does not establish compaction depth or density.

Keep amplitude separate from vibration frequency and the selected operating mode. It describes drum movement rather than the number of cycles. Compare the identified machine settings and the material or layer being compacted; a larger amplitude is not an unconditional improvement for every surface or lift.

Anti-two-block device

A protective device intended to prevent the hook block or another load-handling component contacting the boom tip or upper block. Distinguish a warning aid from a required stopping device in the actual crane configuration.

Identify whether the particular system warns, stops a function or provides another stated response. Its presence does not establish the condition or correct setup of the whole crane. The hook, block and boom arrangement still need the applicable inspection and operating procedure.

Arm tear-out force

The force at the bucket tooth produced by the stick cylinder pulling the stick toward the machine, also called stick digging force. Its measurement method is set out in ISO 6015. See breakout and digging force.

Articulated dump truck

An off-highway haul vehicle with an articulated connection between vehicle sections. Its approved terrain, load and operating limits remain model-specific.

Articulation lock

A mechanical restraint for an articulated joint. Install/remove it under the actual machine’s service/transport procedure; the required arrangement is not universal.

The lock restrains movement between the frames during the operations specified by the machine instructions. Identify its actual installation and retaining parts before work near that joint. It is not a substitute for the other shutdown or support requirements, and it must be handled under the prescribed operating sequence.

Ballast

Weight added to change a machine's balance or traction. It can be carried as fluid in the tires, as cast weights on the wheels, or on the rear hitch, and the three behave differently because they act at different distances from the axles.

Where the added mass acts matters as well as how much it weighs. Wheel weights, tire liquid and a hitch-mounted weight act in different locations. Keep the permitted ballast arrangement with the tractor and attachment instructions rather than treating any added weight as an equivalent change to balance or traction.

Berm

A raised barrier along a roadway or drop-off. Required location and dimensions depend on the applicable rule and site; a berm is not proof that a vehicle cannot cross the edge.

Blade pull

The force a motor grader can drive its blade forward with. It depends on the weight on the drive wheels and on traction, and it rises with machine weight. See motor graders.

Breakout force

The force a loader can generate to prise material loose, usually by curling the bucket. It is not a lifting capacity and a machine can be strong at one and modest at the other.

Read the force definition, measurement location and tool geometry beside the value. A bucket-curl force and a force from another linkage motion need not describe the same test. Neither one independently states the payload that the complete machine may carry or place at a required height.

Breakover angle

The abrupt change of slope where a loading ramp meets the trailer deck. A machine can have ample power and traction to climb the ramp and still ground out crossing this transition.

Bridge formula

A Federal Highway Administration relationship limiting the weight carried on a group of axles according to the distance between them. A short, heavy combination can be inside the gross limit and over the bridge formula.

Category (hitch)

A standardized three-point hitch interface category. Matching category helps establish connection dimensions; it does not by itself establish lift capacity, clearance, usable travel or implement approval.

Cetane number

A measure of how readily diesel fuel ignites under compression, specified in ASTM D975. Higher cetane means shorter ignition delay, which generally improves cold starting and reduces combustion noise.

Ignition quality is a different property from the fuel behavior described by cloud point. A fuel can have a stated cetane value while its cold-flow properties still require attention for the actual conditions. Follow the engine and fuel requirements instead of choosing diesel by one specification alone.

Check valve (holding valve)

A valve arrangement that controls flow in a load-supporting circuit. An ordinary one-way check and a purpose-designed load-holding/hose-failure arrangement are not interchangeable descriptions.

Circle (grader)

The large ring under a motor grader that carries the moldboard and rotates it from cutting to spreading positions. Play in its drive shows as slack in the blade and is expensive to correct.

Cloud point

A fuel’s test-defined temperature at which wax crystals become visibly detectable. It is not a universal engine no-start temperature or the same measure as every cold-filter test.

Wax formation can affect cold-flow behavior and filtration. The label does not identify every cause of a cold-weather starting or fuel-supply problem. Keep the actual fuel specification, temperature conditions and prescribed checks together rather than assuming that a tank containing fuel guarantees an adequate supply to the engine.

Cutting edge

A replaceable steel edge on the front of a bucket, blade or moldboard that does the cutting and protects the parent steel. Some can be turned or flipped to use an unworn edge. See wear parts.

Derate

A reduction of permitted engine output by its control/protection system. Engine protection and emissions inducement are different possible reasons; identify the actual warning. See DPF regeneration and DEF: derate diagnosis.

Diesel exhaust fluid (DEF)

A solution of about 32.5 per cent high-purity urea in water, sprayed into the exhaust of a selective catalytic reduction system to reduce nitrogen oxides. Its quality is set by ISO 22241, and it freezes at about 12 degrees Fahrenheit. See storage and quality.

Draft control

Hitch control responding to a measured draft/load signal to adjust implement position. Sensor location, control response and permitted setup depend on the tractor.

Draft response and position control answer different hitch questions. The former responds to the draft demand sensed by its system; the latter concerns the selected linkage position. Identify the fitted controls and the implement instructions before using one mode as a substitute for the other.

Drawbar pull

The force a tractor delivers to a towed implement through the drawbar. It is limited by the weight on the driven wheels and the traction coefficient, not by engine power alone. See drawbar pull and traction.

Elevated sprocket

A dozer undercarriage design that raises the drive sprocket above the track frame, keeping the drive train out of mud and isolating it from ground shock. It is a design choice, not a universal advantage.

Field efficiency

The share of working time spent doing work rather than turning, overlapping, repositioning or stopping. It is the term that separates a theoretical coverage rate from a real one.

Final drive

The final stage of the propulsion drive delivering torque to a wheel or track drive. Identify the actual gearing, lubrication and service requirements rather than assuming every final drive uses the same oil case.

Flat-face coupler

A quick-action hydraulic coupling described in ISO 16028 whose mating faces are flat, so they can be wiped clean and trap very little dirt or air. Common on construction equipment.

Flotation

How well a machine stays on top of soft ground instead of sinking, set by its ground pressure and the ground's bearing capacity. See ground pressure and flotation.

Frequency (vibratory)

The number of vibration cycles per unit time. Hertz means cycles per second; multiply Hz by 60 for cycles per minute. Keep the actual setting and measurement label with the figure.

Read whether the value is expressed as cycles per second or per minute and keep it with the amplitude and operating mode. Frequency alone does not describe the complete compaction action. The material, layer and required verification remain part of choosing the roller setting.

GAWR

Gross axle weight rating: the manufacturer’s axle-system rating. Added axle ratings do not automatically establish vehicle GVWR or an allowable loaded combination.

GCWR

Gross combination weight rating. Compare it with the applicable loaded vehicle/trailer combination; axle, vehicle, towing and connection limits remain separate checks.

Gradeability

A published grade-performance figure under stated conditions. It is not a slope-stability or braking approval. See speed and gradeability.

Grapple

A gripping attachment for the specified material and carrier. Its own mass and load geometry belong in the carrier-capacity assessment.

Ground pressure

A pressure figure based on a stated load and contact-area method. A nominal average does not describe every local pressure or prove the ground can support the machine.

Grouser

The rib across a track shoe that bites into the ground for traction. A grouser worn nearly flat gives poor traction and is a measure of undercarriage wear.

A worn grouser can reduce the shoe’s ability to engage the surface, but its appearance does not measure the whole undercarriage. Chains, rollers, idlers, sprockets and the applicable wear measurements need their own inspection. Compare the actual shoe design and ground condition when assessing traction.

GVWR

Gross vehicle weight rating: the manufacturer’s rating for the loaded vehicle. Subtracting actual empty weight gives an arithmetic payload margin, subject to all other applicable limits.

Heaped capacity

The volume a bucket holds with material piled above its edges at a defined angle of repose. Struck capacity is the same bucket levelled flush. Both are volumes; neither is a weight.

Hydraulic horsepower

Theoretical fluid power is simultaneous flow multiplied by pressure difference: US gpm × psi ÷ 1714 gives hp; L/min×bar÷600 gives kW, before relevant losses. See hydraulic power.

Hydrostatic transmission

A propulsion arrangement using hydraulic pump/motor displacement and control to transmit power. Speed ranges, reversing method and operating limits depend on the system.

The pump and motor arrangement provides a variable drive relationship. That description does not establish every control response, efficiency or heat condition on a particular machine. Keep the actual drive, operating mode and service instructions with the comparison rather than assuming all hydrostatic models have identical behavior.

Idler

A non-driving track-guiding wheel. Its position and any tension-adjustment function depend on the undercarriage design.

Jib

An auxiliary crane-boom element used in specified configurations to change reach/height. Use its own approved load-chart conditions rather than a main-boom maximum.

Lattice boom

A crane boom built as a steel truss from pinned sections, light for its length, so it gives long reach and high capacity. Its length is set by adding or removing sections; see crawler cranes.

Load center

The specified distance to a load’s center of gravity used in a fork/attachment rating. A different load center requires the applicable chart; proportional arithmetic alone does not approve a derating.

For the fork example, identify the stated reference face and the actual load’s center of gravity. A deep pallet or a heavy component at one end can move that center. The fork-face distance is not automatically the distance from the carrier’s tipping axis, so the complete configured rating still matters.

Load chart

A table or diagram showing the rated load a telehandler, crane or excavator can lift at each reach and height for a stated configuration. See Lift capacity: reading a load chart.

Load chart (crane)

The maker's table of a crane's rated load at each boom length, radius and outrigger position. It, and not the name-plate maximum, is the rating; see reading a crane load chart.

Lowboy

A trailer with a deck lowered between a raised neck and the rear axles, used to carry tall or heavy equipment within the legal height limit. A removable-gooseneck version detaches the neck for drive-on loading. See lowboy and deck types.

MFWD

Mechanical front-wheel drive. Correct tire combinations and rolling-circumference relationship depend on the tractor’s axle/transmission design and approved fitments.

The fitted front and rear tires work with the machine’s prescribed axle and rolling arrangement. A sidewall size or a visually similar tire is not enough to approve a substitution. Check the permitted combination and relevant tire data rather than assuming nominal diameter alone establishes the required match.

Moldboard

The shaped blade surface on equipment such as a grader or plow. Dimensions and working arrangement are equipment-specific.

NLGI grade

A grease-consistency classification. It does not by itself identify base-oil viscosity, thickener compatibility or approval for a particular bearing/joint.

Oil analysis

Testing of a representative lubricant sample for specified properties, contamination and wear evidence. Sampling method, history and other findings affect interpretation; one metal reading does not identify one failed part.

Keep the sample location, operating history, fluid changes and sampling method with the laboratory result. A trend is more informative when those conditions are understood. An isolated abnormal value can prompt investigation, but it cannot identify every failed component or replace the applicable inspection and diagnostic procedure.

Operating weight

The weight of a machine in a stated working configuration, commonly with fluids, a full fuel tank and an operator of a stated weight. What else it includes varies by maker, so the footnote matters. See reading a spec sheet.

Read the included operator, fluids, attachments and options in the publication’s footnote. Then identify what differs on the machine being used or moved. Do not add an attachment twice when the quoted basis includes it, or treat the catalog entry as a scale measurement of every delivered unit.

Outrigger

A beam that extends from a mobile crane's carrier and sets a float on the ground, widening the footprint and moving the tipping line outward. See crane setup.

Overrunning clutch

A device allowing relative overrun in one direction without the same drive-torque transfer. Fitted location and protection function must match the actual driveline.

This device addresses torque transmitted back from a coasting implement toward the tractor side. It performs a different function from overload protection provided by a slip clutch or shear device. Its presence does not remove guarding, shutdown or correct driveline-installation requirements for the complete implement.

Parallelogram ripper

A ripper with linkage geometry intended to control shank attitude during movement. Its penetration and force capability still depend on the specific machine and working position.

Percent grade

The rise over the run times 100. A 100 per cent grade is a 45-degree slope, and a 58 per cent grade is about 30 degrees.

Pick and carry

Traveling with a suspended load under an expressly permitted crane duty. Use the applicable traveling-load chart and conditions; a stationary outrigger capacity is not the rating.

Poppet coupler

The general-purpose agricultural quick-action hydraulic coupler described in ISO 5675. It does not mate with the flat-face type used on construction equipment.

Product identification number (PIN)

The machine identifier under the manufacturer’s applicable numbering system. Record it separately from engine/assembly identifiers and use the correct serial range. See Serial numbers and model decoding: equipment identification.

PTO horsepower

Power at the power-take-off output under stated conditions. Retain shaft/engine speed and rating/test identity rather than inferring one universal loss from engine power.

Radius (crane)

The horizontal working radius defined by the load chart, generally from the crane’s rotation axis to the vertical load line. It is not distance along the boom.

Rated operating capacity

A manufacturer’s operating-capacity figure under a stated method/configuration. Retain the tipping-load percentage and other conditions; 35% and 50% figures can both be published for one track loader.

Regeneration

Soot oxidation in a diesel particulate filter under the system’s permitted process. It does not remove all ash or repair every DEF, sensor or engine-protection fault.

The required conditions and controls depend on the identified engine and aftertreatment system. A warning or reduced-power condition needs its prescribed response. More engine load is not a universal remedy, and an emissions label alone cannot establish the fitted filter, available regeneration modes or cause of a warning.

Retarder

A supplementary speed-retarding system using the actual engine, transmission or other mechanism. Its permitted duty and cooling/braking limits are model-specific.

Use the performance information for the identified vehicle and travel conditions. A retarder is a different part of the braking assessment from the service brakes, and the applicable downhill guidance is not a general permission for every speed, payload or road. Keep the complete braking system and configuration in view.

Ripper

Heavy shanks on the rear of a dozer that break hard or compacted ground and weathered rock so the blade can move it.

ROPS

Rollover protective structure. It preserves a survivable volume around the seat during a rollover and works only in combination with the seat belt that keeps the operator inside that volume.

Rotator

A rotating attachment element used to orient a tool such as a grapple. Continuous hydraulic transfer may use a rotary union; an electrical slip ring is a different component.

Scarifier

A toothed or shanked attachment/system used to loosen material. Position, adjustment and permitted surface finish depend on the equipment and work.

Choose depth and pass sequence from the tool instructions and the surface being worked. Teeth can loosen compacted material for later redistribution, but they are not restricted by a universal first-pass-only rule. Inspect their points, mounting and retention before treating a poor cutting result as insufficient tractor power.

Shear bolt

A specified fastener forming an overload-protection element. Use the prescribed grade, dimensions and assembly; arbitrary substitution changes protection behavior.

The specified dimensions and material grade belong with the protection arrangement. A stronger replacement can change the overload response and transfer damaging force elsewhere. Repeated failure calls for the applicable diagnosis.

Keep the specified protection in place; physical fit alone cannot identify the correct replacement hardware.

Slew ring (swing bearing)

A large bearing supporting relative rotation of an upper structure and carrier; a geared arrangement may also transmit swing drive. Condition and service limits need the actual design.

Slip (wheel slip)

The difference between reference wheel travel and actual vehicle travel under the stated calculation method. A useful operating target depends on tires, drive, ground and work; it is not one universal percentage.

Slip clutch

A friction torque limiter in a driveline. Use its specified inspection, service and setting procedure; do not loosen or deliberately slip every design by a generic seasonal rule.

Follow the identified clutch’s inspection, adjustment and service procedure. Its ability to slip under the prescribed conditions matters; simply seeing the assembly on the shaft cannot establish that it is functioning correctly. Do not transfer a setting from another implement or tighten it until every interruption disappears.

SMV emblem

A fluorescent/retroreflective slow-moving-vehicle identification emblem. Apply the governing road rules and required condition/placement; it does not replace every other required lamp or marking.

Static linear load

The stated static load assigned to a roller drum divided by its width. Identify the drum load and units; it is not the whole machine’s mass divided by any convenient width.

Struck capacity

The volume a bucket holds when the material is levelled flush with the top edge. Heaped capacity adds a pile above it at a stated slope.

Stump jumper

A blade-carrier design used on certain rotary cutters to reduce some obstruction interactions. It does not make striking obstacles harmless or replace the prescribed operating clearances.

A protective pan or carrier beneath a cutter changes how the assembly meets an obstruction. It does not make every strike harmless or establish the condition of the blades, fasteners and driveline protection. Check the actual cutter design and its permitted application before relying on the name.

Tail swing

How far an excavator's counterweight overhangs its tracks when the upper structure rotates. Conventional, reduced and zero tail swing describe how much, and it decides which sites a machine can work.

Thumb

A jaw mounted on an excavator stick that closes against the bucket, turning it into a grab for brush, rock and logs. See couplers and thumbs.

Tilt rotator

An attachment interface providing specified rotation and tilt. Its added mass, geometry, connections and approved tool combination belong in the carrier-capacity assessment.

Tipping load

A load determined by the applicable tipping criterion and test/calculation method. Retain machine configuration, turning position, attachment and any tire-deflection assumptions.

Tongue weight

The vertical trailer load carried at the hitch under the specified loading condition. Use the actual trailer/tow-vehicle/connection requirements rather than a universal percentage.

Traction coefficient

The ratio of the greatest pull a machine can develop to the weight on its driving wheels or tracks. It is high on firm dry ground and low on loose sand, wet clay or ice.

Undercarriage

The track-support and running-gear system, including the fitted track, rollers, idlers, drive components and frame. Inspect component condition and compatibility; hours alone do not establish remaining life.

Universal mounting plate

A commonly used attachment-interface description, not proof of universal compatibility. Confirm the actual dimensions, locks, carrier approval and hydraulic/control requirements.

Working load limit

The stated maximum service load rating under the component’s prescribed conditions. It is not breaking strength; assembly rating can be limited by its weakest applicable component.

Identify the component or assembly to which the marking applies and the stated loading conditions. Breaking strength and permitted service load are different quantities. The complete connection includes its other components and configuration; a large figure on one item cannot establish the rating or restraint of the whole system.

Use the complete rating definition

A quoted maximum without the measurement point, operating condition or configuration can answer a different question from the one being asked. Use specification meanings for measurement examples, Equipment standards and regulations: attachment interfaces for connection requirements and equipment decision routes for the next practical check.