Crane Types, Configurations, Capacities and Load Charts
What 'non-slewing' means
A non-slewing mobile crane cannot slew (rotate) its boom while carrying a load; it travels and lifts with a fixed orientation, typically a pick-and-carry or articulated/rough-terrain configuration. Capacity is therefore governed by the load chart for the specific boom configuration, boom length, radius and outrigger or tyre condition. Key variables: boom length and angle, counterweight, outrigger spread (fully extended, part extended, or on tyres), tyre pressure, and travel path condition.
Reading a load chart
Every chart has a structure: rows for radius, columns for boom length or configuration, and separate sections for on-tyres versus outrigger use. Deductions must be made for lifting gear (slings, shackles, spreader beams) to get net capacity, and for any attached attachments. The chart capacity is a maximum under ideal conditions - it does not account for wind, ground slope, dynamic effects, or side loading.
Traps
Common traps: using the chart for the wrong configuration (e.g. on-tyres figures when outriggers are deployed); forgetting to deduct rigging mass; assuming capacity is constant across the boom length; and ignoring that the chart applies to a level, firm surface. Another trap is confusing rated capacity with tipping capacity.
Worked rule of thumb
Always calculate: net capacity = chart capacity − mass of all lifting gear − mass of attachments. Then compare to the load plus a margin. If the load is at or near the chart limit, the lift needs a documented plan and a competent person's sign-off.