Learn about cranes
A boom truck is a telescopic crane mounted on a commercial truck chassis. Its boom is a set of nested steel sections pushed out by hydraulics, its outriggers turn the truck into a wide, stable base, and its load chart says how much it can safely lift at each reach. Below are 30 facts, each with a source.
In the crane trade, a boom truck means a stiff-boom telescopic crane mounted on a flat-bed commercial truck chassis. One person can operate it and drive it to several jobs in the same day. That is the same basic setup as the Skyhook truck: a red telescopic boom on a white Ford work truck.
Source: Crane Briefing: Boom trucks remain all-American machineBecause the crane sits on a regular commercial chassis, a boom truck can legally travel on the road at highway speeds and sets up faster than a bigger crane. That is a big reason they show up for air conditioner installs and commercial roofing jobs. Less time hauling and rigging the crane means more time lifting.
Source: CONEXPO-CON/AGG: Boom truck advancements drive its popularity on job sitesA telescopic boom is a stack of steel sections nested one inside the next, like a giant spyglass. A hydraulic cylinder pushes the sections out and pulls them back in. Some designs use one cylinder plus ropes to move the outer sections, and others use a single cylinder that pins and locks each section in place one at a time.
Source: Liebherr: Telescoping technology for mobile cranesOutriggers are the legs that swing or slide out from the truck and press down on pads. OSHA's crane rule says they must be fully extended, or set the way the load chart allows, and set so the truck's weight comes off its wheels. A wider stance is what lets the crane lift without tipping.
Source: J.J. Keller: Outriggers and stabilizers (OSHA 1926.1404)A crane's load chart lists how much it can lift at each radius, measured from the crane's center pin to the center of the load. The farther out the load goes, the less the crane can handle, and the drop is steep. That is why a crane is always strongest close in and why operators ask exactly where the load has to land.
Source: Bigge: How to read a load chartThink of a crane as a seesaw: the load pulls one way, while the truck's weight and counterweight push back. Safety rules cap the rated load for a crane on fully set outriggers at 85 percent of the load that would actually tip it. That built-in cushion is one more reason never to guess at a weight.
Source: California Code of Regulations, Title 8, Section 4923: Load rating chartA jib is an add-on section that gives a crane extra reach past the end of its main boom. Boom trucks can have them too. One swing-cab boom truck model, for example, offers a 36-foot lattice jib for jobs that need more reach.
Source: CONEXPO-CON/AGG: Boom truck advancements drive its popularity on job sitesOSHA does not let a crane be set up unless the ground is firm, drained and graded well enough to meet the manufacturer's support and level requirements. When the ground needs help, crews use blocking, mats or cribbing under the outrigger pads. Soft dirt, fresh fill or a hidden pool line can all change a setup.
Source: J.J. Keller: OSHA 1926.1402 Ground conditionsOSHA requires telescopic boom cranes built after February 28, 1992 to have a device that automatically prevents damage when the hook block or overhaul ball runs up into the boom tip. It has to work at every point where that could happen. OSHA groups it with the other operational aids that help the operator run the crane safely.
Source: OSHA 29 CFR 1926.1416: Operational aidsWhen a crane swings, its rotating upper section can strike or pinch anyone standing too close. OSHA requires warning lines, railings or similar barriers to mark that zone. If the operator knows someone has stepped inside it, the crane must not swing until that person is confirmed to be in a safe spot.
Source: OSHA 29 CFR 1926.1424: Work area controlUnder OSHA 1926.1427, employers must make sure crane operators on construction work are trained, certified or licensed, and evaluated before they run the equipment. There are exceptions, including derricks, sideboom cranes and equipment rated at 2,000 pounds or less. A certification from an accredited testing organization is good for five years.
Source: OSHA 29 CFR 1926.1427: Operator qualification and certificationThe knuckle-boom cranes on many supply trucks are excluded from OSHA's construction crane rule when they only unload material to the ground, or set packaged building supplies onto a structure with a fork and a working overload device. The carve-out ends when the crane holds material in place or handles prefabricated parts like roof trusses. Then the full crane rule applies.
Source: OSHA 29 CFR 1926.1400: ScopeOSHA requires a signal person whenever the operator can't fully see the spot where the load is being set, or can't see ahead while the equipment travels. One is also required whenever the operator or the person handling the load decides site conditions call for one. On a rooftop lift, the landing spot is often out of the operator's view.
Source: OSHA 29 CFR 1926.1419: Signals, general requirementsNormally only one person signals the crane at a time. But OSHA says anyone who sees a safety problem must alert the operator or signal person with the stop or emergency stop signal, and the operator must obey it. The helper on the roof has just as much right to stop the lift as the foreman.
Source: OSHA 29 CFR 1926.1419: Signals, general requirementsFor lines up to 350,000 volts, a common way to meet the OSHA rule is to keep every part of the crane, the hoist line and the load at least 20 feet from the line. Lines over 350,000 volts need 50 feet under that approach. Crews must treat every line as live unless the utility confirms it is de-energized and grounded.
Source: APS: Cranes and derricks, clearance from overhead linesWind pushes on the boom and on the load, especially big flat loads like a shed. OSHA requires the competent person on site to adjust the equipment or the operation for the effect of wind on stability and rated capacity. Sometimes the safest move is simply to wait for the gusts to pass.
Source: OSHA 29 CFR 1926.1417: OperationOSHA requires a competent person to start a visual inspection of a crane before each shift it will be used. On top of that, a qualified person must do a full inspection at least every 12 months, with functional testing. Think of it as a daily walk-around plus a yearly checkup.
Source: OSHA 29 CFR 1926.1412: InspectionsTwo-blocking is crane talk for the moment the hook block or ball gets pulled up against the top of the boom. If power keeps being applied, the hoist rope or other parts can fail.
Source: OSHA 29 CFR 1926.1401: DefinitionsThat heavy steel ball above the hook has a real name: an overhaul ball. Its weight keeps the cable taut when nothing is hanging from it. Crews also call it the headache ball, and you can probably guess why nobody wants to stand under one.
Source: Wikipedia: Overhaul ballMany cranes have two hoist lines: the main hoist and an auxiliary hoist, nicknamed the whipline. Riggers even have separate hand signals to pick which one to use. Tap the top of your head for the main hoist, or tap your elbow for the whipline, then give the regular hoist or lower signal.
Source: OSHA 1926 Subpart CC, Appendix A: Standard hand signalsThe lifting machine takes its name from the crane, the tall wading bird. Its long, reaching neck looked a lot like the arm of an early lifting machine. The word for the bird goes back to Old English.
Source: Wikipedia: Crane (machine)Around 1600, "derrick" meant a hangman or a gallows, after the surname of a hangman at London's Tyburn gallows. By the 1720s the word meant a hoisting machine for heavy weights. Later, Americans used it for the tower over an oil well.
Source: Online Etymology Dictionary: derrickCranes for heavy loads go back to ancient Greece in the late sixth century BC. The proof is in the stones: temple blocks have special cuttings made for lifting tongs and lewis irons, special grips used to hoist the blocks into place.
Source: New World Encyclopedia: Crane (machine)A Roman pulley crane called the polyspaston, worked by four men at a winch, could lift about 3,000 kg, roughly 6,600 pounds. Swap the winch for a big treadwheel that workers walked inside, and the load could double with half the crew. Treadwheel cranes were still building castles and cathedrals in the Middle Ages.
Source: Wikipedia: Treadwheel craneWilliam Armstrong's first hydraulic crane was working on the quay at Newcastle, England, before the end of 1846. Early versions ran on water pressure from a reservoir that sat well above the quays, so the town's water pipes did the lifting. Today's boom trucks still lift with hydraulic cylinders.
Source: Grace's Guide: William ArmstrongMilwaukee Hydraulics Corp. launched the H-2 Hydrocrane in 1946. It had a telescopic boom and hydraulic outriggers and could be mounted on any two-ton truck. That is basically the recipe for a modern boom truck.
Source: Construction Equipment: America's first hydraulic craneThe Swedish company Hiab had its HIAB 190 ready for production in 1947, and calls it the world's first hydraulic crane. It was a loader crane built to mount on trucks. It could lift a maximum of one tonne. The founder's motto was "One man should be able to do the job!"
Source: Hiab: HIAB 190, the first of manyRay Pitman, a World War II veteran who ran a utility business, built the first boom truck. Pitman Manufacturing started production in 1950, and National Crane began building boom trucks in 1952. Early models were rated from 5 to 30 tons.
Source: Crane Briefing: Boom trucks remain all-American machineMammoet's SK6000 ring crane is billed as the world's strongest land-based crane. It was tested in 2024 to a load moment of 520,000 tonne-meters and can lift loads of up to 3,000 tonnes to heights of up to 220 meters. It is built for giant energy projects, not backyard spas.
Source: Equipment Journal: Mammoet completes testing of world's strongest land-based craneLiebherr's LTM 11200-9.1 mobile crane rides on nine axles and has a 100-meter telescopic boom, which Liebherr calls the longest telescopic boom in the world. Its maximum capacity is 1,200 tonnes. It works on the same tubes-inside-tubes idea as a boom truck, just scaled way up.
Source: Liebherr: LTM 11200-9.1Want the longer version? See how a crane lift works or our HVAC crane lifts page.
A rooftop change-out is usually a short lift with tight timing. The crew is on the roof, the old unit is disconnected, and everyone is waiting on the crane. A boom truck fits that job because it drives on regular roads at highway speed and sets up faster than a bigger crane, so the lift happens without a long setup.
A boom truck also fits where HVAC work happens: residential driveways, side streets and commercial parking lots. Some cities require a right-of-way or street-use permit to set up in the street, so check with your city. HVAC contractors can learn more on our page for HVAC contractors.
Every lift is different. Call with the weight of the item, how far it needs to go and where the truck can park, and Don will confirm the lift. Call 602-615-0712 or text 623-258-8361 to schedule.
The machine is named after the crane, a tall bird with a long neck. People saw a resemblance between the bird's reaching neck and the long arm of a lifting machine, and the name stuck. The bird's name itself goes back to Old English. A related word, derrick, has a darker story: it came from the surname of a London hangman around 1600.
Outriggers give the truck a wider, more stable base so it can lift without tipping. OSHA's crane rule says they must be fully extended, or set the way the load chart allows, and set so the truck's weight comes off its wheels. The ground under the pads also has to be firm, drained and graded, and crews add blocking or mats when it needs help.
For most construction crane work, yes. OSHA 1926.1427 requires employers to make sure operators are trained, certified or licensed, and evaluated before running covered equipment. Exceptions include derricks, sideboom cranes and equipment rated at 2,000 pounds or less, and some knuckle-boom material delivery work falls outside the crane rule entirely. Certifications from accredited testing organizations are valid for five years.
For lines up to 350,000 volts, a common way to meet OSHA's rule is to keep every part of the crane, the hoist line and the load at least 20 feet away. Lines over 350,000 volts need 50 feet under that approach. Every line is treated as live unless the utility confirms it is de-energized and visibly grounded at the site.
Got something that needs to go over the roof? Call or text Don with the item, its rough weight and where the truck can park.
