Screw - distance ratio
A screw is a mechanism that converts rotational motion to linear motion, and a torque (rotational force) to a linear force. It is one of the six classical simple machines. The most common form consists of a cylindrical shaft with helical grooves or ridges called threads around the outside.
The distance ratio of a simple machine is defined as the ratio of the distance the applied force moves to the distance the load moves. For a screw it is the ratio of the circular distance din a point on the edge of the shaft moves to the linear distance dout the shaft moves. If r is the radius of the shaft, in one turn a point on the screw’s rim moves a distance of 2πr, while its shaft moves linearly by the lead distance l. So the distance ratio is given by the shown formula.Related formulas
|DR||distance ratio (dimensionless)|
|r||radius of the shaft (m)|
|l||lead of the screw (m)|