There are cases where a moving machine part requires a pit in a floor and to achieve maximum safety, this pit can be covered with the motion of the machine. In such cases a pit cover is the perfect protection. Even better is being able to utilise the pit cover is a floor surface.
In most cases, a pit cover is driven by an electric motor and in those cases where the moving machine part pulls out the pit cover, the motor is used to keep the pit cover taut and to roll it back. In some cases, the motor is used for moving the pit cover in both directions.
A spring motor might also be used to roll out and roll back the pit cover.