Load capacity is the maximum weight a machine — crane, telehandler, forklift, or loader — can lift or support under defined conditions, expressed in kilograms, metric tons, or pounds. It is never a single fixed number for the whole machine. Instead, it is a variable value that changes with outreach, boom length, boom angle, counterweight configuration, and support conditions such as outriggers extended or retracted.
How Load Capacity Is Determined
Manufacturers establish load capacity through structural and stability calculations, then publish the results as load charts (also called capacity charts or duty charts). These charts cross-reference variables such as radius or outreach against boom angle or extension length, with the intersection giving the maximum permissible load for that specific configuration. Capacity decreases as radius increases, since a load positioned farther from the machine's center of rotation or tipping axis generates a larger overturning moment.
For telehandlers, load capacity is additionally tied to a defined load center — the horizontal distance from the front face of the fork to the load's center of gravity. A common reference load center is 24 in (61 cm) measured from the front vertical face of the fork arm; loads with a load center beyond this reference distance require a reduced capacity value read from a separate zone of the chart. Using the load chart of one machine or one attachment configuration for another is not valid, even within the same model family, because fork length, carriage type, and counterweight all affect the rating.
Factors Affecting Load Capacity
Several conditions alter the rated capacity of a given machine:
Outreach or radius: capacity drops as the load moves farther from the machine's base or pivot point.
Boom configuration: fully extended booms, higher boom angles, or specific jib combinations each carry their own rating.
Support condition: outriggers fully extended, partially extended, or on rubber tires each correspond to a different chart section, since ground bearing area and stability change accordingly.
Ground conditions: load-bearing capacity of the supporting surface affects whether the charted capacity can safely be applied, independent of the machine's structural rating.
Attachment and carriage type: fork carriages, winches, or jibs change the center of gravity and permissible load.
Load Capacity in Different Equipment Categories
In mobile and tower cranes, load capacity is published per radius and boom configuration, and advances in rope technology can shift these values. Fibre-rope systems, for instance, have been used to increase load capacity by around 40 percent over conventional steel-rope equivalents on the same crane model, because the lighter rope reduces the load acting on the hoist system itself.
In telehandlers, load capacity ranges vary widely by model and lift height. Compact models rated for lower lift heights typically carry capacities starting around 1,400 kg, while larger models with lift heights up to roughly 17 m can reach capacities of 4,000 kg or more.
In slewing ring bearings used in cranes and excavators, load capacity is a function of rolling element configuration: single-row ball bearings using a four-point contact arrangement suit light to medium loads, while larger raceway designs with rollers are specified for heavier duty cycles.
Practical Relevance for Planning and Procurement
For planners and equipment buyers, load capacity figures are only meaningful together with the corresponding radius, configuration, and support condition — a single maximum figure without these parameters cannot be used to verify whether a machine suits a given lift. Procurement decisions, particularly for rental equipment, increasingly specify load capacity alongside lift height and emission compliance as core technical parameters rather than relying on brand or model name alone.
Load Capacity in Trade Coverage
Coverage of telehandler load charts has addressed how capacity zones are structured around boom extension length and lift angle, and why fork carriage ratings based on a specific load center cannot be transferred between machines, as detailed in Telehandler Load Chart Interpretation: Capacity Zones and Safe Operation. Model-specific capacity figures for telehandlers, ranging from 1,400 kg to 4,000 kg across different lift height classes, were documented in JCB: How the British Brand Became Synonymous with Backhoe Loaders Worldwide. A case where fibre-rope technology increased crane load capacity by 40 percent over steel-rope equivalents, applied on tower cranes lifting a bridge section in Ulm, was reported in Seven Liebherr Tower Cranes Lift Ulm's New B10 Wallstraßenbrücke Between Active Tracks.
