Which type of thread has a width approximately equal to its depth with equal spacing?

The correct choice is the square thread. A square thread is characterized by its profile, which has a width that is approximately equal to its depth. This design leads to efficient power transmission when used in applications like lead screws. The equal spacing between the threads allows for smooth engagement and disengagement, which is particularly useful in applications requiring minimal friction.

Square threads are often utilized in scenarios where high efficiency is necessary, as the shape reduces the amount of friction compared to other thread types, leading to better load handling and preventing wear. The geometry also allows for higher axial loads without significant deformation or failure.

In contrast, other thread types such as Acme, Buttress, and Whitworth have different profiles and characteristics. Acme threads have a trapezoidal shape that provides a balance of strength and ease of manufacture but do not maintain an equal width-to-depth ratio like square threads. Buttress threads, designed for applications involving mainly axial loads in one direction, have a unique profile tailored for strength in that specific loading direction. Lastly, Whitworth threads have a rounded profile which improves the fit and reduces stress concentrations, but they also deviate from the width-to-depth ratio found in square threads. Each of these thread types is optimized for specific applications, highlighting the advantages