What effect does the jib angle offset have on the crane capacity?

What effect does the jib angle offset have on the crane capacity?

• A. Capacity will be increased
• B. Capacity will be decreased
• C. No effect
• D. Capacity depends on load

Answer: (B)

When the jib is offset from the crane’s centerline, the load’s line of action isn’t aligned with the base. This creates a larger horizontal force and a bigger overturning moment on the crane as you lift. To keep the crane stable and within safe limits, the capacity is reduced as the offset increases. In other words, more offset means derating the lifting capacity, so the safe load you can lift becomes smaller. The exact amount of derating depends on the radius and the specific crane model, which is why load charts show lower capacities at different offsets. If the jib were not offset, the horizontal component would be smaller and the capacity would be higher.

When the jib is offset from the crane’s centerline, the load’s line of action isn’t aligned with the base. This creates a larger horizontal force and a bigger overturning moment on the crane as you lift. To keep the crane stable and within safe limits, the capacity is reduced as the offset increases. In other words, more offset means derating the lifting capacity, so the safe load you can lift becomes smaller. The exact amount of derating depends on the radius and the specific crane model, which is why load charts show lower capacities at different offsets. If the jib were not offset, the horizontal component would be smaller and the capacity would be higher.