The words you will meet in crane training and on the job, grouped by the part of the work they belong to so you can read one area at a time.
The last block is separate on purpose: it holds the definitions written into OSHA 1926 Subpart CC, the crane and derrick standard, in the regulation's own wording. Those are the ones a written test is most likely to quote at you. Everything above it is the everyday vocabulary the courses use.
Sections: The machine: carrier, upperworks and drives · Booms, jibs and boom geometry · Set-up, ground support and stability · Load charts and capacity · Wire rope, reeving and blocks · Rigging and handling the load · Signals, communication and roles · Power lines and electrical hazards · Inspection and taking a crane out of service · Definitions from OSHA 1926 Subpart CC.
The machine: carrier, upperworks and drives
Carrier. The lower part of a mobile crane: the chassis, axles, wheels or tracks that the crane travels on and that the upperworks turns on top of.
Cab. The operator's station. Which part of the crane it sits on is what separates a swing cab machine from a fixed cab one.
Swing cab. A crane whose operator's station is mounted on the upperworks, so the cab turns with the boom and the operator always faces the load.
Fixed cab. A crane whose operator's station is part of the carrier and does not turn with the boom. Boom trucks and carry-deck cranes are the usual examples. Blind spots are larger, so a signal person is needed more often.
Swing circle (turntable, slewing bearing). The bearing and gear between the carrier and the upperworks that lets the upperworks rotate.
Axis of rotation. The vertical centreline the upperworks turns about. Load radius is measured horizontally from this line.
Boom foot pin (heel pin). The pin at the base of the boom that the boom pivots on. Boom length is measured from here.
Power take-off (PTO). A drive off the engine or transmission that turns the crane's hydraulic pump.
Hydraulic pump. Driven by the engine through the PTO, it supplies the oil flow that works the boom, outriggers, swing and hoists.
Holding valve (check valve, counterbalance valve). A valve at a cylinder port that traps the oil inside if a hose or connection fails, so a boom cannot drop and an outrigger jack cannot collapse. All three names are used for the same device.
Outriggers (stabilizers). Beams that extend from the carrier with jacks that push down on floats, widening the crane's base and lifting the tires clear of the ground.
Outrigger beam. The horizontal member that slides out from the carrier and sets how wide the crane's base is.
Outrigger jack. The vertical cylinder at the end of an outrigger beam that takes the crane's weight down onto the float.
Float (outrigger pad, pontoon). The plate at the bottom of an outrigger jack that spreads the load onto the ground or onto blocking. It must sit square to the jack and be latched to it.
Outrigger spread. The distance across the set outriggers. Charts are written for specific spreads, such as fully retracted, intermediate extended and fully extended, and every beam must be set to the same one.
Crawler tracks. The continuous belts a crawler crane travels and lifts on. They take the place of outriggers as the base for stability.
Gantry (A-frame). The raised frame on a lattice crane that the boom suspension ropes or pendants run over. Raising it changes the angle the boom is supported at.
Boom hoist. The drum or cylinder that raises and lowers the boom, changing the boom angle.
Hoist drum. The drum the hoist rope winds onto. Line pull falls as rope builds up in layers on it.
Main hoist. The primary winch and rope, usually reeved with several parts to a hook block for heavy loads.
Auxiliary hoist. A second winch and rope, usually single part to a ball, for lighter and faster work. It can have a lower rating than the main hoist.
Booms, jibs and boom geometry
Telescopic boom. A boom whose length is changed by sliding powered sections in and out of a base section.
Lattice boom. A boom built from open steel sections pinned together. Its length changes only by adding or removing sections.
Boom sections. The parts a boom is made of. On a telescopic boom, typically a base section with inner mid, outer mid and tip sections that telescope out of it.
Boom mode. A manufacturer's defined pattern for how a telescopic boom's powered sections are extended. The same overall boom length in a different mode can carry a different rating, so the mode selects which capacity table applies.
Boom length. The length of the boom from the boom foot pin to the boom tip sheave pin, as extended.
Boom angle. The angle of the boom above horizontal.
Loaded boom angle. The boom angle once the rated load is on the hook at the rated radius. It is lower than the unloaded angle, because the boom deflects.
Boom deflection. The bending of the boom under load. It increases the radius as the load comes off the ground, which is why a no-load angle or radius cannot be used on its own.
Boom stops. Devices that stop the boom being raised past its maximum angle and pulled over backwards.
Boom tip (boom head, boom point). The top end of the boom, carrying the sheaves the hoist rope runs over.
Auxiliary boom head (aux head). A single sheave added at the boom head for a second line, usually with a ball on it. It is deducted from capacity like any other attachment.
Jib. An extension pinned to the boom tip to gain height or reach. It is rated on its own chart, not on the main boom chart.
Fly. Another name for a jib on a telescopic crane, often stowed along the side of the boom until it is needed.
Boom extension. A general name for a jib or fly: anything pinned on past the boom tip to add length.
Offset. The angle a jib or fly is pinned at relative to the centreline of the main boom. Each offset has its own rating table, and a larger offset rates lower.
Stowed. An extension carried on the boom but not rigged for use. It is still weight on the crane, so it is a deduction from the main boom capacity.
Erected. An extension pinned out into its working position. If you are lifting from it, use its chart; if you are not, check whether the combination is rated at all.
Tip height. How high the boom tip reaches above the ground at a given boom length and angle. Read off the range diagram.
Set-up, ground support and stability
Level. A crane set so the upperworks turns in a horizontal plane. Many manufacturers require within one percent, and being out of level costs capacity because the radius grows as the boom swings toward the low side.
Ground bearing pressure. The pressure a float or track puts into the ground, worked out as the load divided by the supporting area.
Allowable bearing capacity. How much pressure the ground underneath can carry without failing. The supporting area must be large enough that the pressure stays under it.
Mats. Large timber or engineered panels laid under floats or tracks to spread load over weak ground.
Tipping axis. The line the crane would rotate about if it tipped, running through the supports on the side the load is over. Stability is leverage about this line.
Stability. The crane's resistance to tipping, set by the weight of the machine and counterweight working against the load and its radius.
Stability limit. A rating set by how close the crane is to tipping rather than by the strength of its parts. Usually the limit at longer radius.
Structural limit. A rating set by the strength of the boom, hoist or other components. It is usually the limit at short radius, where the crane would break before it tipped, and it is marked on the chart by shading, bold type or an asterisk.
On outriggers. Set up with the outriggers extended, the jacks down and the tires clear of the ground, using the outrigger tables.
On rubber (on tires). Lifting with the crane's weight on its tires rather than its outriggers, using a separate and much lower set of ratings. If the tires still carry any weight, the outrigger chart does not apply.
Working area. The sector the boom is over relative to the carrier, such as over the rear, over the side, over the front, or a full 360 degrees. Each area can carry a different rating.
Over the side. Boom swung out over the side of the carrier. On most mobile cranes this is the weakest and least stable area.
Over the front. Boom swung over the front of the carrier. On a fixed cab crane this is over the truck cab, and it is normally rated lower or not permitted at all.
Over the rear. Boom swung over the back of the carrier, usually the strongest area on a truck-mounted crane.
Pick and carry. Travelling with a suspended load. It is rated lower than a stationary lift and carries its own conditions on speed, boom position and ground.
Load charts and capacity
Load chart. The manufacturer's document giving what the crane may lift in each configuration. It is written for that crane's serial number and must be in the cab.
Configuration. The exact way the crane is set up: outrigger position, counterweight, boom mode, boom length, working area, jib state and reeving. The chart only applies to the configuration it is written for.
Load radius. The horizontal distance from the axis of rotation to the centre of the hook, with the load suspended.
Gross capacity. The rated load in the chart for the crane's exact configuration. It includes the weight of every load-handling device.
Net capacity. Gross capacity minus every deduction. It is the heaviest actual load you may pick.
Deduction. The weight of anything hanging on the crane that is not the load itself: hook block, ball, slings, spreader bars, stowed jib, auxiliary head. Deductions come off gross capacity.
Gross load. The total weight the crane is carrying, including the load, the rigging and all the load-handling equipment.
Net load. The weight of the load by itself, without the rigging and load-handling equipment.
Capacity table. The grid of rated loads, normally with radius down the side and boom length across the top.
Boom angle table. A table giving the boom angle that produces a given radius at a given boom length, or the ratings read by angle rather than radius.
Range diagram (working range diagram). A scale drawing showing what radius and tip height each boom length reaches at each angle. It is also what you estimate rope lengths from.
Working area diagram. A plan view showing the sectors the chart's ratings apply in, and the lines between them.
Shaded values. Chart numbers marked by shading, bold type or an asterisk to show the rating is set by structural strength rather than stability.
Interpolating. Estimating a value part-way between two printed chart numbers. It is not allowed unless the chart's own notes say so.
Next larger radius. The rule for a radius that is not printed: move down the chart to the next listed radius. How close you are to the row above makes no difference.
Next longer or next shorter boom length, whichever is smaller. The rule for a boom length that is not printed: read both neighbouring columns, compare the two ratings, and use the smaller one. Deductions then come off that number, and any other by-boom-length figure is taken from that same column.
Wire rope, reeving and blocks
Parts of line. The number of falls of rope carrying the hook block between the boom head and the block. More parts lift more and hoist slower.
Reeving. The way the rope is threaded through the boom head and block sheaves to make up the parts of line.
Excessive reeving. Reeving more parts than the load actually needs. Some charts treat the extra rope as a deduction at a stated weight per foot, so extra parts are not a free safety margin.
Line pull. How hard the winch can pull on the rope. It falls as rope builds up in layers on the drum, so the first layer pulls hardest.
Allowable line pull. The most that may be put on one part of the rope. Multiplied by the parts of line, it gives a limit that can be lower than the chart capacity, in which case the rope governs the lift.
Drum layer. One wrap of rope across the width of the drum. Each added layer increases the drum's effective diameter and reduces line pull.
Two full wraps. The minimum amount of rope that must stay on the drum with the hook at its lowest point, so the rope is never pulled off its anchorage.
Sheave. A grooved wheel the rope runs over. The groove must match the rope size.
Hanger sheave. An extra sheave hung at the boom head to carry the additional falls when reeving to three or four parts. It is load-handling equipment, so it is a deduction.
Hook block. The assembly of sheaves, frame and hook that the rope is reeved through. Its weight is always a deduction.
Overhaul ball (headache ball). A weighted ball on a single part of line, heavy enough to pull the rope down. Its weight is a deduction.
Whip line. A light single-part line, usually off the auxiliary hoist, used for fast handling of light loads.
Load line (hoist line). The rope running from the hoist drum over the boom head to the load.
Rotation-resistant rope. Rope built so a load on a single part will not spin. That construction costs strength, so it has its own lower line pull figures and is not interchangeable with standard rope.
IWRC. Independent wire rope core: a rope whose core is itself a small wire rope, giving more strength and crush resistance than a fibre core.
Breaking strength. The load at which a rope fails. Working limits are a fraction of it.
Design factor (safety factor). The ratio between a rope or fitting's breaking strength and the load it is allowed to carry.
Anti-two-block device. A device that warns of, or prevents, the block being pulled up into the boom tip. Hoisting up, telescoping out and booming down can all cause two-blocking.
Rigging and handling the load
Rigging. The slings, shackles, spreader bars and other hardware between the hook and the load. Its weight is a deduction.
Sling. A wire rope, chain, synthetic web or round sling used to attach a load to the hook.
Shackle. A U-shaped fitting closed with a pin, used to connect slings to a load or to each other.
Spreader bar. A bar that holds sling legs apart so they pull vertically, keeping sling tension down. It is a deduction.
Lifting beam. A beam that carries the load in bending from one or more pick points, used where a spreader will not suit.
Sling angle. The angle a sling leg makes with the horizontal. As the angle drops, the tension in each leg rises sharply.
Certified weight. A load weight from a reliable documented source, such as a shipping document or a weigh ticket, rather than an estimate.
Static load. The load with everything still. Charts are written for static loads in ideal conditions.
Dynamic load. The extra loading created by movement: starting, stopping, swinging, or snatching a load off the ground. It does not appear on the chart, and smooth operation is how you control it.
Side loading. Pulling the boom sideways rather than straight down the line of the boom. Booms are weak sideways, and this is a common way to damage one.
Free fall. Lowering with the drum disengaged from the drive so the load descends under gravity. It is prohibited in several situations, including when people are under or being hoisted by the load.
Land the load. Set the load down and secure it. An operator must do this before leaving the controls.
Signals, communication and roles
Signal person. The person who directs the operator when the operator cannot see the load or its path, or when the equipment is travelling with limited view. They must meet the qualification requirements.
Hand signals. The standard set of arm and hand signals used to direct a crane. The standard chart must be posted at the job site.
Voice signals. Directions given by radio or other voice link. Each one names the function, the direction and the distance, and the operator confirms before acting.
Stop signal. A signal to stop the lift. It must be obeyed whoever gives it, not only the designated signal person.
A/D director. The person who supervises assembly and disassembly. They must meet the criteria for both a competent person and a qualified person, or be a competent person assisted by one.
Controlling entity. The employer, owner or contractor with overall responsibility for the project, including ground conditions being adequate for the crane.
Pre-lift meeting. The briefing before the lift where the plan, the weights, the path, the hazards and everybody's role are agreed. Anyone present can call a stop.
Trainee. An operator in training, who must be continuously monitored on site by their trainer.
Power lines and electrical hazards
Minimum approach distance. The closest any part of the crane, the load line or the load may come to an energized power line, set by the line's voltage.
Encroachment. Any part of the crane, rigging or load breaching the minimum approach distance to a power line.
Energized. Carrying electrical current. A line is assumed energized at its maximum voltage until the utility owner confirms it is de-energized and visibly grounded.
De-energized and grounded. The line switched off and visibly earthed by the utility owner. Only then does the power line rule change.
Step potential. The voltage difference between the ground under one foot and the other when current is spreading through the earth from a contact. It is why you keep your feet together.
Touch potential. The voltage difference between an energized object and the ground, which is why nobody touches a crane that is in contact with a line.
Stay in the cab. The rule for an operator whose crane contacts a power line: remain in the cab, try to break contact by moving the crane clear, and if you must leave, jump clear without touching crane and ground at once, landing with feet together and shuffling or hopping away.
Inspection and taking a crane out of service
Shift inspection. A visual check by a competent person before or during each shift, covering the items the standard lists. It is not normally recorded.
Monthly inspection. The same scope as the shift inspection, but documented, with the findings and the inspector kept on file.
Annual (comprehensive) inspection. A yearly inspection by a qualified person covering the whole machine, including items that need disassembly to see. It is documented and kept.
Out of service. A crane taken out of use because a deficiency is a safety hazard. It stays out until the deficiency is corrected.
Lockout / tagout. Isolating and marking equipment so it cannot be started while somebody is working on it.
Operator's manual. The manufacturer's instructions for that machine. Where it is stricter than a general rule, it governs.
Definitions from OSHA 1926 Subpart CC
These are the crane and derrick standard's own definitions, in the regulation's wording. Definitions that only apply to marine, tower and diving work are left out.
Articulating crane. A crane whose boom consists of a series of folding, pin-connected structural members, typically manipulated to extend or retract by power from hydraulic cylinders.
Assembly/Disassembly. The assembly and/or disassembly of equipment covered under the crane standard.
Assist crane. A crane used to assist in assembling or disassembling a crane.
Attachments. Any device that expands the range of tasks that can be done by the equipment. Examples include an auger, drill, magnet, piledriver and boom-attached personnel platform.
Audible signal. A signal made by a distinct sound or series of sounds, such as those made by a bell, horn or whistle.
Blocking (also called cribbing). Wood or other material used to support equipment or a component and distribute loads to the ground. It is typically used to support lattice boom sections during assembly/disassembly and under outrigger and stabilizer floats.
Boom. An inclined spar, strut or other long structural member which supports the upper hoisting tackle on a crane or derrick. The length and vertical angle of the boom can usually be varied to achieve increased height or reach. Booms are grouped into hydraulically extendible, cantilevered, latticed section, cable-supported and articulating types.
Boom angle indicator. A device which measures the angle of the boom relative to horizontal.
Boom length indicator. Indicates the length of the permanent part of the boom (such as ruled markings on the boom) or, in some computerized systems, the length of the boom with extensions or attachments.
Center of gravity. The point in an object around which its weight is evenly distributed. If you could put a support under that point, you could balance the object on it.
Competent person. One who is capable of identifying existing and predictable hazards in the surroundings or working conditions which are unsanitary, hazardous or dangerous to employees, and who has authorization to take prompt corrective measures to eliminate them.
Counterweight. A weight used to supplement the weight of equipment in providing stability for lifting loads by counterbalancing those loads.
Crawler crane. Equipment that has a type of base mounting which incorporates a continuous belt of sprocket-driven track.
Dedicated channel. A line of communication assigned by the employer who controls the communication system to only one signal person and crane/derrick, or to a coordinated group of cranes/derricks/signal persons.
Dedicated spotter (power lines). A person who meets the signal person qualification requirements and whose sole responsibility is to watch the separation between the power line and the equipment, load line and load (including rigging and lifting accessories), and ensure through communication with the operator that the applicable minimum approach distance is not breached.
Drum rotation indicator. A device on a crane or hoist which indicates in which direction and at what relative speed a particular hoist drum is turning.
Electrical contact. Occurs when a person, object or equipment makes contact or comes in close proximity with an energized conductor or equipment that allows the passage of current.
Fall zone. The area (including the area directly beneath the load) in which it is reasonably foreseeable that partially or completely suspended materials could fall in the event of an accident.
Hoist. A mechanical device for lifting and lowering loads by winding a line onto or off a drum.
Hoisting. The act of raising, lowering or otherwise moving a load in the air with equipment covered by the crane standard.
Insulating link/device. An insulating device listed, labeled or accepted by a Nationally Recognized Testing Laboratory.
Jib stop (jib backstop). The same type of device as a boom stop, but for a fixed or luffing jib.
Land crane/derrick. Equipment not originally designed by the manufacturer for marine use by permanent attachment to barges, pontoons, vessels or other means of flotation.
Load. The object(s) being hoisted, or the weight of the object(s). Both uses include the load-attaching equipment, such as the load block, ropes, slings, shackles and any other ancillary attachment.
Load moment (rated capacity) indicator. A system which aids the operator by sensing (directly or indirectly) the overturning moment on the equipment (load multiplied by radius). It compares this lifting condition to the rated capacity, and indicates the percentage of capacity at which the equipment is working. Lights, bells or buzzers may warn of an approaching overload.
Load moment (rated capacity) limiter. A system which senses the overturning moment and compares it to the rated capacity. When the rated capacity is reached, it shuts off power to the functions that can increase the severity of loading, such as hoisting, telescoping out or luffing out. Functions that decrease the loading, such as lowering, telescoping in or luffing in, typically stay operational.
Luffing jib. A jib that can change its radius independent of the main boom.
Mobile crane. A lifting device incorporating a cable-suspended latticed boom or hydraulic telescopic boom designed to be moved between operating locations by transport over the road.
Nonconductive. Because of the nature and condition of the materials used, and the conditions of use, the object has the property of not becoming energized: it has high dielectric properties offering a high resistance to the passage of current.
Operational aids. Devices that assist the operator in the safe operation of the crane by providing information or automatically taking control of a crane function.
Operational controls. Levers, switches, pedals and other devices for controlling equipment operation.
Operator. A person who is operating the equipment.
Pendants. Fixed-length wire rope (with fittings at both ends) or bars used to pin segments of a boom suspension system together. Typically used on lattice boom cranes to change the length of the suspension when the boom length changes, without changing the rope on the drum.
Power lines. Electric transmission and distribution lines.
Proximity alarm. A device that warns of proximity to a power line and has been listed, labeled or accepted by a Nationally Recognized Testing Laboratory.
Qualified person. A person who, by possession of a recognized degree, certificate or professional standing, or by extensive knowledge, training and experience, has successfully demonstrated the ability to solve or resolve problems relating to the subject matter, the work or the project.
Qualified rigger. A rigger who meets the criteria for a qualified person.
Range control limit device. A device that can be set by an operator to limit movement of the boom or jib tip to a plane or multiple planes.
Range control warning device. A device that can be set by an operator to warn that the boom or jib tip is at a plane or multiple planes.
Rated capacity. The maximum working load permitted by the manufacturer under specified working conditions. These typically include a specific combination of equipment configuration, radius, boom length and other parameters of use.
Repetitive pickup points. When operating on a short cycle operation, the rope is used on a single layer and spooled repetitively over a short portion of the drum.
Running wire rope. A wire rope that moves over sheaves or drums.
Special hazard warnings. Warnings of site-specific hazards, for example the proximity of power lines.
Tagline. A rope (usually fiber) attached to a lifted load to control load spinning and pendular motions, or used to stabilize a bucket or magnet during material handling.
Tilt up or tilt down operation. Raising or lowering a load from horizontal to vertical, or vertical to horizontal.
Two blocking. A condition in which the component uppermost on the hoist line, such as the load block, hook block or overhaul ball, comes in contact with the boom tip, fixed upper block or similar component. This binds the system, and continued application of power can cause failure of the hoist rope or another component.
Upperworks / Superstructure / Upperstructure. The revolving frame of the equipment on which the operating machinery (and in many cases the engine) is mounted, along with the operator's cab. The counterweight is typically supported on the rear, and the boom or other front-end attachment is mounted on the front.
Wire rope. A flexible rope constructed by laying steel wires into various patterns of multi-wired strands around a core system to produce a helically wound rope.