What feature allowed early hydraulic elevators to be used for high-rise applications?

The use of a system of ropes and multiple sheaves enabled early hydraulic elevators to effectively handle the challenges associated with high-rise applications. This system allows for the distribution of the load and improves the efficiency of the lifting mechanism. By employing multiple sheaves, the elevator can take advantage of mechanical advantage, which reduces the force that must be applied by the hydraulic system to lift the elevator car and its load.

This design element was crucial as hydraulic systems inherently face limitations regarding how much weight they can lift and how high they can effectively operate. The introduction of ropes and sheaves in this context enhanced the performance of hydraulic elevators, allowing them to service taller buildings than was previously possible with direct hydraulic systems.

In contrast, while electric motors, counterweight systems, and automatic leveling technology each play vital roles in modern elevator systems, they do not fundamentally relate to the primary feature that gave early hydraulic elevators their heightened usability for high-rise buildings. For instance, electric motors transformed elevator technology overall but were not a unique feature exclusive to hydraulic systems at the time.