Glossary Updates12 new terms added to the glossaries · October 2, 2026, 22:44 CEST
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Glossary · Guards and machine motion

Interlocking guard

German: Verriegelte trennende Schutzeinrichtung

In machine safety, an interlocking guard is a guard associated with an interlocking device so that hazardous machine functions are controlled by guard position: they cannot run until the guard is closed, and opening the guard issues a stop command.

  • Machine safety
  • EU

In one sentence

An interlocking guard links a movable guard to the control system so hazardous functions stop when it opens; closing it must not restart the machine.

Example

Opening the hinged door of a robot cell actuates a coded interlock switch, and the safety PLC stops the robot before anyone can reach it.

How it applies

  • Machine safety: An interlocking guard without guard locking is only suitable if the hazardous motion stops before a person can reach it. Compare the stopping time with the time needed to open the guard and reach in, or add guard locking.
  • Functional safety: The guard position monitoring is a safety function. Its interlocking device and logic must meet the required Performance Level or SIL; ISO 14119 covers the selection of interlocking devices.
  • Design: Closing the guard must not by itself start hazardous functions. A separate start command is required (restart prevention).
  • Technical documentation: Describe what happens when the guard is opened in each operating mode, how to check the interlock and the test interval.

Interlocking guard vs. interlocking guard with guard locking

A plain interlocking guard can be opened at any time and stops the machine when opened. An interlocking guard with guard locking stays locked until the hazard has ceased.

By knowledge.aitechdoc.world · Published September 25, 2026 · Last reviewed

Source: ISO 12100:2010, Safety of machinery — General principles for design — Risk assessment and risk reduction

Definitions follow the cited standards and specifications. Where a source is a copyrighted publication, such as an ISO, IEC or EN standard, the definition is a close paraphrase, not a verbatim quotation, so as not to infringe copyright. We recommend reading the original publication. The sections “How it applies” are editorial commentary by AI TechDoc Blog and are not part of any standard.

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