For a single-start screw, how do lead and pitch compare?

For a single-start screw, how do lead and pitch compare?

• A. Lead equals pitch
• B. Lead is greater than pitch
• C. Pitch is greater than lead
• D. Lead and pitch are unrelated

Answer: (A)

The main idea is how lead and pitch relate in screw threads. Pitch is the distance between successive threads along the axis, while lead is how far the nut (or screw) moves axially with one full turn. In a single-start screw there is only one thread winding around the shaft, so one complete rotation advances the screw by exactly one pitch. So the lead and the pitch are the same. For example, if the pitch is 2 mm, a full turn moves 2 mm. If there were multiple starts, the lead would be larger than the pitch, since lead = pitch × number of starts.

The main idea is how lead and pitch relate in screw threads. Pitch is the distance between successive threads along the axis, while lead is how far the nut (or screw) moves axially with one full turn. In a single-start screw there is only one thread winding around the shaft, so one complete rotation advances the screw by exactly one pitch. So the lead and the pitch are the same. For example, if the pitch is 2 mm, a full turn moves 2 mm. If there were multiple starts, the lead would be larger than the pitch, since lead = pitch × number of starts.