Most wheeled cranes (boom trucks, AT cranes, knuckle boom cranes) are strongest in which quadrant?

• A. Over the front
• B. Over the rear
• C. Over the left
• D. Over the right

Answer: (B)

The main idea is stability when lifting on a wheeled crane comes from how the weight is distributed and where the counterweight sits. On most wheeled cranes the counterweight and engine are at the rear, so when you swing the load toward the rear of the truck, the pulling force of the load is countered by that heavy weight at the back. That rearward load pushes the tipping tendency toward the front edge of the base, which the rear counterweight and rear stabilizers resist more effectively. In practical terms, the crane can handle a larger load when the hook and load are over the rear quadrant because the balance is favorable and the base is better resisting tipping.

Lifting over the front is harder to stabilize because the front end is more prone to lift and the available counterbalancing moment is reduced, which lowers the capacity for that direction. Side-to-side directions are typically similar in strength due to symmetrical design, so they don’t offer the same advantage as the rear quadrant.

So, the strongest quadrant for most wheeled cranes is over the rear.