Types of MEWPs and their safety features

Choosing the right MEWP starts with knowing what each type can and cannot do. The machines look different, but they share the same basic parts: a chassis that carries the weight and provides stability, an extending structure that raises the platform, and a work platform with guardrails and controls. Differences in those three parts decide where each machine can go, how high and far it reaches, how much it can carry and which hazards are most important.

Group A machines

On a Group A machine, the center of the platform stays within the tipping lines, the lines joining the wheels or outriggers that the machine would tip over. Because the load stays above the base, Group A machines are relatively stable in the vertical direction. Their main hazards are overturning on slopes, potholes and curbs; entrapment against overhead structure; and falls when workers climb on guardrails or lean out.

• Vertical mast lifts, sometimes called personnel lifts, carry one person on a small platform raised by a telescoping mast. Push-around versions must be moved with the platform lowered; self-propelled versions may drive elevated. They are used for light maintenance and stock picking in tight indoor spaces.
• Slab scissor lifts run on solid, non-marking tires and are designed for level, hard surfaces such as concrete floors. Most are electric. Platform heights range from about 4 m to about 15 m.
• Rough-terrain scissor lifts have pneumatic or foam-filled tires, more ground clearance and often outriggers or leveling jacks. Many are diesel, dual-fuel or hybrid. They are designed for compacted ground on construction sites, not for mud, soft fill or steep slopes.

Group B machines

On a Group B machine, the platform can move outside the tipping lines. The boom works like a lever: the further out the platform goes, the greater the overturning moment, and the counterweight and chassis must resist it. Group B machines bring reach, which lets workers get over obstacles and out to façades, but they add hazards that Group A machines do not have.

• Telescopic booms (straight booms) extend in a straight line and give the greatest horizontal reach. They are used for steel erection, façade work and work over obstacles.
• Articulating booms (knuckle booms) have two or more sections that fold, often with a short jib at the platform. They can reach up and over obstacles and down into spaces, which makes them useful around building structure and inside plants.
• Trailer-mounted and truck-mounted booms are towed or carried on a vehicle and set on outriggers. Vehicle-mounted aerial devices used by utilities and arborists are designed to their own standards and are often insulated for electrical work.

The extra hazards of Group B machines include the catapult effect, where a jolt at the chassis whips the boom and can throw the occupant out; entrapment against structure as the platform swings; and greater exposure to power lines because the platform can reach toward them. These are the reasons the regulations and manufacturers require occupants of boom lifts to wear a harness with a short lanyard attached to the platform anchorage.

Types 1, 2 and 3

The type describes how a machine travels.

IPAF's incident reports use these categories. In its report on 2025 incidents, Category 3b machines, self-propelled booms, appeared in about a quarter of reports, and Category 3a machines, self-propelled scissors and mast lifts, in about another quarter. Both families need attention.

Safety features built into current machines

Machines built to ANSI A92.20 or the equivalent ISO standard carry safety features that older machines may lack. A supervisor should know what each feature does, so that a crew does not bypass it or treat an older machine as if it had it.

Wind rating is another design feature. Machines rated for outdoor use are designed to remain stable in winds up to a stated speed, typically 12.5 m/s (about 45 km/h or 28 mph) under the current standards. Machines rated for indoor use only have a wind rating of zero: they must not be used outdoors at all, even on a calm day, because a gust can tip them. The rating is on the machine's decals and in the manual. Lesson 9 covers wind in detail.

Reading the specification plate

Every MEWP carries a manufacturer's plate and decals. They are the quickest way to check whether a machine fits the job.

Many scissor lifts have a lower outdoor rating than indoor rating because wind force on people and materials adds to the overturning moment. Crews that work inside most of the time often miss this when they take the same machine outside.

Older machines and rental fleets

Machines built before the current standards took effect may lack load sensing, have different wind ratings or use older terms on their decals. They can still be used if they are maintained, inspected and used according to their manufacturer's instructions and the law, but supervisors should check what features they have rather than assume. Rental companies are a good source of information: they must provide the manual and familiarization information and can advise on which machine suits a task.

The categories are a convenient shorthand. When planning a job, write the group and type of the selected machine in the safe use plan and check them against each operator's training record.

Power sources

MEWPs run on batteries, internal combustion engines or both. The power source affects where a machine can work and what hazards it brings.

Supervisors often meet the power source question when a machine moves from outdoor to indoor work. A diesel boom that was fine in a parking lot can build up dangerous levels of carbon monoxide inside a building within minutes. Choose an electric or hybrid machine for indoor work, or plan ventilation and monitoring.