Which statement describes buttress thread properties?

• A. It has two types: a lead screw form and a hydraulic sealing form.
• B. It has a 60-degree thread angle.
• C. It is identical to a square thread.
• D. It is used only for decorative fixtures.

Answer: (A)

Buttress threads are designed with an asymmetric profile so they can handle high thrust in one direction while limiting strength in the opposite direction. This makes them especially useful in power screws and hydraulic applications where one-way load carrying is important. The statement about two forms reflects how practitioners tailor the buttress shape for different jobs: a lead screw form, optimized for converting rotation to linear motion under heavy axial load, and a hydraulic sealing form, designed to help create and maintain a seal under pressure.

The other ideas don’t fit the typical use or geometry of buttress threads. They aren’t defined by a fixed 60-degree angle like some symmetric thread types, they aren’t identical to square threads, and they aren’t used purely for decoration.