Captive fasteners

When are captive fasteners to apply?

Since the commencement of the machinery directive 2006/42/EC the builder of machines ask the question: When we have to use captive fasteners? Following requirement about the captive fasteners on protections could be found in the machinery directive (appendix No.:

Fixed guards

The attachments of the fixed guards could only detached with tools. The fasteners have to be connected with the safety guards or the machine after detaching the safety guard. Fixed guards may not be in a stow position after detaching of the captive fasteners.

Wing bolt will be introduced in practice – these are absolutely prohibited

Captive fasteners from protections, which could be opened by hand, like thumb nuts, were prohibited also according to the old machinery directive.
Before the machinery directive comes into force, it sufficed, to apply fittings only with help of a tool. But indifferent if it is a wing bolt or a fixed bolt. Again and again the safety guards didn’t get fixxed correct and the bolts disappeared. Workers should get awared concerning by applying the cover, by stay of the fasteners on the machine or the safety guards

All things „captive“, a bolt loose

Cyclic / sudden intervention

The proposals of the „capative“ of fasteners are to perform if the producer provide a cyclic intervention over the safety guard in the machine. For possible sudden intervention, for example repair, remediation or something else, the requirement above doesn’t apply.

Deployment of captive bolts



cleaning lid

Installation of a fence around the danger zone

Cover above a lubricating point

Covers which get only removed when there are repairs or sanitations

strap cover on drives (if a cyclic change of a strap is necessary)


expendable part covers


Table: examples of the necessary of captive bolts.

Include captive bolts only by a cyclic intervention



How to captive fasteners be conducted?

In the EN 953:1997+A1:2009 Safety of machinery - Guards - General requirements for the design and construction of fixed and movable guards, the following example of an captive fastener will be shown:

Picture 11 – Example of an captive fastener

On the internet there were different remarks provided from manufacturers.

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