The Centurion is a positive mode, thumbwheel operated machine guard locking interlock switch that locks the guard closed until the operator manually rotates the thumbwheel, retracting the shaft from the guard door. The action of retracting the shaft initiates two functions, it isolates the power to the machine while the guard is open and, due to the operating principle, gives up to 20 seconds delay before the guard can be opened. Alternative styles with longer shafts can increase the time delay by as much as 50 percent . The Centurion is ideal for use on simple machines with short, constant run down times. It is important that correct installation and operation of the unit are followed to ensure that the retractable shaft cannot be extended when the guard is open. For machines with long or variable run down times or where frequent access is required, solenoid locking switches such as the TLS-GD2 and Atlas 5 should be considered.