Power-transmitting screw threads: best choice when power is transmitted in one direction only Select the thread form that is mechanically best suited for heavy load transmission predominantly in a single direction. Choose the correct option.

Concept
Buttress threads combine the high efficiency of a square thread in the load direction with a stronger tooth form, making them ideal where heavy force acts primarily in one direction (e.g., presses, jacks).

Why others are less suitable
Square is efficient but weaker at the root; Acme is stronger but less efficient; Knuckle is for rough/rolling engagement, not precision power screws.

Final Answer
Buttress threads