Select from the Mechanical Trapped Key Range

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Fortress Product Feature - mGard Trapped Key Range

Trapped key interlocking is versatile, robust and can be used to solve complex safety sequences, particularly where multiple energy sources exist. Electrical, pneumatic, hydraulic, and kinetic energy sources can all be interlocked using mGard products, and typically at a fraction of the cost of alternative solutions.


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What is Trapped Key Interlocking?

📜 Fortress mGard products are designed, tested and TUV approved for use in Category 4/PLe safe control systems. A single Fortress interlock does not require additional safety components added to meet PLe.

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Changing the handing on mechanical products is easy

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🔎   Explore the Range

Control Interlocking

Solenoid Controlled Trapped Key Switches to Enforce Run-Down

Mechanical Timer and Voltage Sensing Solenoid Controlled Solutions

Power Interlocking

Intermediate Transfer

Access Control

Keys and Accessories

Contact us and we can help define your trapped key interlock system.

At Fortress we will always look to assist with project delivery and efficiency by supporting on the design of trapped key interlock systems. Our team can be on hand to survey equipment on site, interpret system drawings or discuss concepts early on in project design.

The advantage of trapped key systems is that any number of power sources can be interlocked into any number of access points. Determining part numbers and a bill of materials may initially appear complex but a Fortress representative can assist with this and provide engineering drawings of each component.

Using key engravings and colour coding will also make sequences easy to understand and simple to follow. With 30 characters of text and 9 colours available we can define a coding system for you and record all keys supplied so every key supplied is unique.

Using end user information and project documentation we can coordinate across multiple integrators and equipment suppliers.


All downloadable assets

To have access to the mGard technical information, please login to

  • Select from our range of high-coded compact yet robust interlocks here.
  • Use our Datasheets / drawing generators to create technical files, datasheets, and CAD for your selected product.
  • Convert your unique ITM number into a Fortress part number using our Reference tool
  • Calculate the performance level of your unique safety system using our SISTEMA library
  • Click here for more Fortress Product tools