What mechanical advantage ratio is created on the top fixed sheave in a two-block hoisting system?

What mechanical advantage ratio is created on the top fixed sheave in a two-block hoisting system?

• A. 2:1
• B. 3:1
• C. None
• D. 4:1

Answer: (C)

The amount of force you gain (mechanical advantage) comes from how many rope segments are supporting the load, not from a pulley that’s fixed in place. A fixed pulley like the top sheave in a two-block hoist simply changes the rope’s direction; it doesn’t multiply the input force. The multiplying comes from the moving block and how many rope parts actually support the load. In a two-block setup, the moving block is the part attached to the load, and the number of rope segments bearing that load determines the MA (for example, two segments give 2:1, four segments give 4:1, etc.). The top fixed sheave guides the rope but does not itself create a mechanical advantage. So there’s no MA created specifically by the top fixed sheave, and the appropriate answer is None.

The amount of force you gain (mechanical advantage) comes from how many rope segments are supporting the load, not from a pulley that’s fixed in place. A fixed pulley like the top sheave in a two-block hoist simply changes the rope’s direction; it doesn’t multiply the input force. The multiplying comes from the moving block and how many rope parts actually support the load.

In a two-block setup, the moving block is the part attached to the load, and the number of rope segments bearing that load determines the MA (for example, two segments give 2:1, four segments give 4:1, etc.). The top fixed sheave guides the rope but does not itself create a mechanical advantage. So there’s no MA created specifically by the top fixed sheave, and the appropriate answer is None.