AutomationDirect has added Dold trapped key systems to its line of safety products. A trapped key system uses a series of mechanical locks and keys to control the access of gates or doors to running equipment or machines, ensuring safe access to those machines. Available in either standard (SX) or solenoid-locking (ZRH) versions, all keys and their corresponding receivers and modules are unique within a set. The SX-series of standard gate sets are 316L stainless steel body interlock safety switches with one normally-closed and two forced opening normally-open/normally-closed changeover contacts. The ZRH-series solenoid gate sets are interlocking safety switches with 24 VAC/DC solenoid power to unlock, one normally-closed and two forced opening normally-open/normally-closed changeover contacts for actuator tongue (key) status and two normally-closed and one forced opening normally-open/normally-closed changeover contacts for solenoid status.