Quick answer: an articulating (knuckle) boom changes shape — it reaches up, over and around obstacles. A telescopic (straight/stick) boom extends in one line — faster and often longer for direct, open reaches. Pick by drawing the path from where the machine can park to where the basket must land: if that line bends, you need the knuckle.
Reach profile is the whole decision
Every boom job is a geometry problem with three numbers:
- Working height — where the basket must end up
- Horizontal outreach — how far sideways from the chassis
- Up-and-over clearance — the height of the obstacle the boom must clear on the way
A telescopic boom maximises the first two along a straight line. An articulating boom spends some of its reach on the elbow — buying the third number. Our 34ft LGMG AR11J knuckle boom shows the shape of the trade: 12.75m working height, 6.78m outreach, 5.32m up-and-over clearance, jib articulation for final placement and a 355° turntable.
Where the knuckle boom wins
- Rooftop plant behind parapets — over the parapet, down to the unit
- Signage and facades above awnings — the classic up-and-over
- Working past ducts, pipe racks and structure in plants and warehouses
- Over landscaping, fences and dock edges where the chassis can’t get close
- Tight bases — knuckles typically position closer to the structure because the riser goes up before the boom goes out
Where the telescopic boom wins
- Long, direct, repeated reaches on open elevations — pure horizontal production work
- Maximum outreach per dollar — no elbow means more stick for the money
- Simple positioning on open ground: park, extend, work
- Bridge, tower and steel work with clear sight lines and nothing to clear
Setup and repositioning
On obstacle-rich sites the knuckle repositions less — it can re-shape instead of re-parking. On open faces the telescopic repositions faster — extend and retract beat fold and unfold. Count the number of set-ups your job needs; it often decides the hire.
Ground still rules
Both classes concentrate serious weight (the AR11J is 5,400kg) through a small footprint, and both amplify lean with reach. Diesel RT versions handle slopes and rough ground within their ratings (45% gradeability on the AR11J, oscillating axle) — but fill, trenches and soft edges must be checked first. See Ground Conditions for Access Equipment.
Licence, harness, safety
The WP high risk work licence applies to boom-type EWPs with boom length 11m or more — both articulating and telescopic; our AR11J requires it. Harness clipped to the designated anchor point in either machine; exclusion zones below the work; a ground person trained on the base controls. Details: Do You Need a Licence for an EWP?
FAQs
What is the main difference? The articulating boom bends to reach around obstacles; the telescopic boom is a straight extending stick — faster and longer on direct lines.
Which is better for facades? Telescopic for open elevations; articulating when awnings, setbacks or street furniture block the straight line.
Which is better for rooftop plant? Articulating — parapets and services almost always block the direct path.
Is an articulating boom always more versatile? Around obstacles, yes. On long open reaches a telescopic is more efficient — versatility you don’t need is just cost.
Which has more outreach? Model by model, telescopics usually reach further horizontally for the same class. Our AR11J knuckle gives 6.78m — enough for most over-awning work.
Which is easier to position? Telescopic on open ground; articulating on cluttered sites where re-shaping beats re-parking.
Can both work on rough terrain? Yes — diesel RT versions of both exist. Slope, support and travel path still need assessment before delivery.
Which is better in tight spaces? Compact electric articulating booms are built for it; big telescopics are not. Indoors, also price a 40ft scissor before any boom.
Do both need the same licence? Same rule for both: WP licence at 11m boom length or more (our AR11J needs it); trained competent operators below that.
What’s the most common mistake? Choosing by maximum height alone. The path the basket travels — especially what it must clear — is what actually rules machines in or out.
Specifications quoted are from the current LGMG AR11J spec sheet and vary by model — confirm before you book.