If a hoist machine roped 1:1 is capable of running at 650 fpm, with a capacity of 4500 lbs, what would its capability be if roped 2:1?

When a hoist machine is configured in a 2:1 roping arrangement, the speed and capacity of the elevator are impacted due to the mechanical advantage provided by the rope configuration.

In a 2:1 roping system, the load is shared across two lengths of rope. This effectively doubles the lifting capacity of the hoist machine while simultaneously halving the speed. Therefore, if the original machine can lift 4500 lbs at a speed of 650 feet per minute (fpm) in a 1:1 arrangement, in a 2:1 configuration, the capacity increases to 9000 lbs, while the speed reduces to 325 fpm.

This calculation is derived from the principles of physics involving pulleys and forces. The relationship between capacity and speed in different roping setups shows that doubling the number of rope lengths allows the elevator to handle more weight, but at a lower speed, as it takes longer for the same motor to lift the increased load due to the added mechanical disadvantage.

As such, a 2:1 hoisting machine configuration results in 325 fpm at 9000 lbs, making this the correct choice based on the fundamental principles of mechanical advantage and elevator operation.