A linear actuator takes energy input in a rotary form and converts it to a straight-line output to perform motion functions. The simplest example of a linear actuator is a common automotive scissors jack. Cranking the rotary handle clockwise turns a screw that pushes a drive nut, expanding the scissors and causing the jack to rise in an upwards linear direction. Cranking counter-clockwise moves it straight back down. Linear actuators may operate from simple mechanical input, like a jack, or electro-mechanical input from a precision stepper motor for accuracy. They can also be driven by hydraulic or pneumatic pressure for applications requiring substantial actuation force.