Some tools have interlocks that protect the operator or other. Foe example, a riding mower has a switch under the operator's seat that shuts off the blades or engine when the operator stands up. This protect the operator from being run over or getting a foot under the mower deck. Riding mower have an interlock switch that stops the blades or engine when the operator selects reverse gear. This prevents the mower from backing over someone with the blades engaged.