The screw can be of single start,double starts or multiple starts.The multiple-start worm gear screw jack is widely used in application which requires higher speed. Then how about the difference between the screw pitch and lead in multiple-start screw?  Let’s see the following information.

Pitch
Pitch is the distance between screw grooves and is commonly used with inch sized products and specified as threads per inch.
Lead
Lead is the linear travel the nut makes per one screw revolution and is how ball screws are typically specified.
The pitch and lead are equal with single start screws. For multiple start screws the lead is the pitch divided by the number of starts.

At last let’s see an actual picture of a double start screw.If any need for high speed multiple-start screw jack,please contact Lude Transmission for more.