The margin of stability values (85% on outriggers and 75% on tires) apply to which type of crane?

The margin of stability values (85% on outriggers and 75% on tires) apply to which type of crane?

• A. Mobile Tower Cranes
• B. Wheeled Truck Cranes
• C. Crawler Cranes
• D. Floating Cranes

Answer: (B)

Margin of stability for mobile cranes depends on how the crane is supported. When outriggers are set, the base becomes wide and stable, so a higher portion of the rated load can be handled safely—85%. If the crane is operating on its tires without outriggers, the base is narrower and tipping risk is higher, so the allowable load drops to 75% of the rated load. These values are the standard MOS guidance for wheeled truck cranes. Other crane types—such as crawlers or floating cranes—rely on different stability setups and do not use these exact margins.

Margin of stability for mobile cranes depends on how the crane is supported. When outriggers are set, the base becomes wide and stable, so a higher portion of the rated load can be handled safely—85%. If the crane is operating on its tires without outriggers, the base is narrower and tipping risk is higher, so the allowable load drops to 75% of the rated load. These values are the standard MOS guidance for wheeled truck cranes. Other crane types—such as crawlers or floating cranes—rely on different stability setups and do not use these exact margins.