For a machine guard safety interlock that offers peak simplicity and essential reliability, use the 440T Prosafe Rotary Trapped Key Safety Interlock Switch by Allen Bradley Guardmaster.

This rugged interlock switch provides sequential access control for machine guard doors. The function of this switch is to help to keep personnel safe by securely locking a machine guard or gate closed and preventing access to dangerous areas. When the guard door is open, power is isolated.

This device is a single key mechanical rotary switch that is panel mounted. It has 4NO contacts and 20 Amp current. It has an operating temperature range of between -10°C and 40°C. It has a rated insulation voltage of 690V. With Prosafe switches the new keys are fully compatible with old style barrels, however old keys do not fit the new barrels. As the key is locked, the switch is ON and when the key is released, the switch is OFF.

This type of robust mechanical trapped key interlocking device is usually used in environments where electrical interlock systems may be unsuitable or expensive to install and maintain, such as areas with explosive atmospheres.

• Robust 316 stainless steel construction for superior durability
• Flush-mount housing
• Direct drive operation—positively opens contacts
• Weatherproof stainless-steel dust cap
• Replaceable code barrel assembly
• Simple and dependable trapped key interlocking

EN292
EN1088
IEC 947-5-1
UL listed
CSA certified
IP20 rated

The Prosafe range of products have been extensively tested for quality and durability, working seamlessly for 100,000 operations. They are also highly tamper-resistant, accepting only the original or equivalent new key for operation. Allen Bradley Guardmaster have one of the broadest portfolios in the industry for machine monitoring and locking products, which ensures that you can create your ideal guarding system and keep your operations running smoothly.

A trapped key interlock is a simple sequential mechanical safety system for machine guards whereby a removable key is trapped in a control device while the power supply is running. Only when the power supply is turned off can the key can be rotated in the lock and withdrawn. While it is removed the power supply is isolated, ensuring that the machine cannot be restarted while the guard door is open. The key can then be used to release the machine guard, allowing access to the machinery. After the guard is closed it can be removed and inserted back into the original control unit, thus allowing the power supply to be activated again. Trapped key interlocks can withstand harsher environments than electrical interlocks and are often used in industrial settings where serious risk of injury can occur to machine operators.