Which type of screw thread is characterized by sloped sides that engage smoothly?

The Acme screw thread is characterized by its trapezoidal shape, which features sloped sides that engage smoothly. This design allows for efficient transfer of linear motion and reduced friction during operation, making it ideal for applications such as lead screws in machinery. The sloped sides facilitate smoother engagement and disengagement, resulting in less wear and improved durability compared to other thread types.

While V-thread screws also have angled sides, they are designed primarily for precision and fastening rather than smooth engagement. Buttress screw threads have a more complex profile tailored for applications that require significant force in one direction, and square screw threads are designed for high efficiency and load-bearing in linear motion applications, but they do not have sloped sides like the Acme thread. The unique design of the Acme thread makes it particularly well-suited for applications where smooth interaction and durability are critical.