How do you choose the right crane size (tonnage)?

The three numbers the operator needs

• Total weight on the hook: the heaviest piece plus slings, shackles and any spreader bar. Use the spec sheet, submittal or bill of lading. Federal rules (29 CFR 1926.1417(o)) require the load weight to be verified before the lift.
• Radius: the horizontal distance from the crane's center pin to the pick point and to the set point. The longest radius usually decides the crane.
• Height: the roof, wall or platform height, plus room for rigging and clearance over parapets and equipment.

Why the number on the crane is misleading

A crane reaches its top rating only at a short radius, with outriggers fully extended and the specified counterweight on. Out at 60 or 80 feet of reach the same machine lifts far less. That's normal, and it's the reason operators ask for distances, not just weights.

Setup space and ground

• Outriggers need room to extend, often fully, for the crane to use its full chart.
• Sandy or recently backfilled ground, irrigation lines, septic systems and buried utilities can call for mats or a different setup spot.
• Canals, trees, carports and power lines can push the crane farther from the load, and more reach usually means a bigger crane.

A rough pattern, not a rule

Light trusses, panels and small condensers often go up with a boom truck or small hydraulic crane. Package units, steel, tanks and farm equipment often need a mid-size mobile crane. Heavy or long-reach work needs bigger cranes. See crane vs. boom truck vs. telehandler for how the machines differ.