National Commission for the Certification of Crane Operators (NCCCO) Mobile Crane Practice Exam

Which area do truck cranes without a 5th outrigger generally have no lifting capacity unless the manufacturer states otherwise?

1. The side

2. The rear

3. The front

4. The outriggers

The correct answer is: The front

Truck cranes without a 5th outrigger typically have significantly reduced lifting capacity at the front. This is due to the inherent design and stability limitations of the crane when utilized without the additional support that a 5th outrigger would provide. The main function of outriggers is to extend the base of the crane, enhancing its stability during lifting operations. Without a 5th outrigger, the crane's ability to support loads at the front is compromised, leading to potential tipping or imbalance issues. The manufacturer may specify certain limitations regarding lifting capacities, but the general understanding is that the front area remains a critical zone where lifting capabilities are minimal or non-existent. In contrast, the side and rear lifting capacities may still be somewhat functional depending on the configuration and design of the crane, but front lifting without the stabilization of a 5th outrigger poses significant risks. Thus, understanding these limitations is essential for safe operation and adherence to manufacturer specifications.