False: A power screw is used not only to convert rotary motion into linear motion but also to transmit power.

A power screw is a simple machine that consists of a threaded shaft (also known as the screw) and a nut. The screw has a helical thread on its surface, while the nut has a corresponding thread that meshes with the screw. When the screw is rotated, the nut moves linearly along the length of the screw.

The primary purpose of a power screw is indeed to convert rotary motion into linear motion. This makes it a very useful mechanism in various applications where linear motion is required. For example, power screws are commonly used in machinery, automotive systems, and industrial equipment to provide precise linear movement.

However, in addition to converting rotary motion into linear motion, power screws are also designed to transmit power. This means that they can transfer torque from a rotating input source (such as a motor or an engine) to the nut, which in turn can be used to perform work or drive other components. The power transmission capability of a power screw is achieved through the frictional forces between the screw and the nut.

The power transmission capability of a power screw is determined by various factors, including the thread profile, pitch, lead, and the coefficient of friction between the screw and the nut. By adjusting these parameters, engineers can optimize the power transmission efficiency and load-carrying capacity of the power screw for a given application.

In summary, a power screw is not only used to convert rotary motion into linear motion but also to transmit power. Its ability to convert rotary motion into linear motion makes it a versatile mechanism in many mechanical systems, while its power transmission capability allows it to transfer torque and perform work.