What is the purpose of outriggers on a mobile crane, and what conditions must be checked before deployment?

• A. Outriggers stabilize the crane during lifts by distributing weight over a larger ground area.
• B. Outriggers stabilize the crane during lifts by distributing weight over a larger ground area; check soil bearing, ensure solid contact pads or cribbing, verify level surface, clear area for deployment, and confirm outriggers are fully extended and correctly positioned.
• C. Outriggers should only be used on paved surfaces.
• D. Outriggers are cosmetic; no checks needed.

Answer: (C)

Outriggers serve to stabilize a mobile crane by spreading the lifting load over a larger ground area. That wider base lowers the pressure under each contact point and counters tipping moments created by the crane's boom and the load being lifted. Proper deployment is essential for safety, because even a strong crane can become unstable if the ground can’t support the forces involved.

Before deploying, you check the conditions that affect stability and load transfer. First, the ground must be suitable to support the crane with the planned lift. Assess the soil bearing capacity and, if needed, place solid contact pads or cribbing to distribute the load more evenly and prevent sinking. The surface should be level and firm to avoid rocking or shifting during the lift. The deployment area must be clear of obstacles, utilities, and personnel, and there must be enough space for the outriggers to extend without striking nearby objects. Finally, ensure the outriggers are fully extended, properly positioned on their pads or cribbing, and that all safety pins or locking devices are engaged, with the crane configured according to the manufacturer’s instructions.