Which drive groove configuration requires a double-wrapped secondary sheave?

The correct configuration that requires a double-wrapped secondary sheave is the U-groove design. U-grooves are typically utilized in elevator systems where the cable or belt must maintain a certain degree of engagement to ensure efficient power transfer and movement. The U-shape allows for a larger surface area of contact and improved grip, which is crucial in applications with significant load requirements.

Double-wrapping occurs to enhance the friction and minimize slip between the drive and the sheave, providing greater traction and stability for the system. This design is particularly adept at accommodating the dynamics of elevator systems where consistent performance and safety are paramount.

In contrast, other groove types, such as V-grooves, round grooves, and flat grooves, have different contact characteristics and are not designed to necessitate a double-wrapped setup. Their geometries influence the way belts or cables interact with the sheave, focusing on either maximizing surface area contact or allowing for easier alignment, rather than providing the specific traction benefits offered by U-grooves with a double-wrap configuration.