The pitch refers to the axial distance travelled by a nut or other threaded component during one complete revolution of a spindle, and is measured in millimetres. For a single-start spindle, the pitch corresponds to the distance between two adjacent threads. For multi-start spindles, the pitch is the product of the thread pitch and the number of starts.
A larger lead results in greater axial movement per revolution of the spindle, thereby enabling a faster feed rate. A smaller lead, on the other hand, results in slower movement but offers greater accuracy.
Power transmission is also influenced by the pitch. Smaller pitches allow for a higher mechanical transmission ratio, greater power transmission and are often self-locking. Larger pitches, on the other hand, have a lower power transmission ratio and are generally not self-locking, which allows for back-run in the event of a loss of power.
Efficiency increases with a steeper lead, particularly in ball screws, as the greater lead angle reduces friction losses. Smaller leads allow for finer motion resolution and are therefore particularly suitable for precision applications such as those found in CNC machines or measuring systems.