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Do your pull rope emergency stops conform?

A Rockwell Automation (Allen-Bradley Guardmaster ) product story
Edited by the Manufacturingtalk editorial team Apr 12, 2001

The correct installation of a rope operated Emergency Stop system is vitally important. Does your safety system conform with safety standards? Now is the time to check, says Guardmaster.

The correct installation of a rope operated Emergency Stop system is vitally important.

If installed correctly, the system offers a lifeline to any person requiring its function.

However, recent research by safety equipment manufacturer, Guardmaster, into the use and installation of rope systems has revealed that some installations utilise a fixed / immovable point at one end of the ropes length and a rope operated safety device at the other.

This is a type of installation, which does not conform to usual Safety Standards, and one, which Guardmaster believes, could result in a loss of the basic safety function.

Guardmaster has for many years promoted the use of two rope operated safety devices, one installed at each end of the rope's length.

This gives the optimum safety function when operating the rope.

With installations of less than 2m, the use of a tensioner spring at one end, and a rope operated safety device at the other, may be used.

This is, however, dependent on the application and associated risk present.

The problem with installing a rope operated system with one fixed point can be understood with reference to Fig 1 below.

To ensure optimum levels of safety protection the switching device must be able to be tripped via a pull on the rope from any direction.

However, with the fixed point system, as shown, a horizontal pull on the rope against the fixed point does not fulfil this requirement.

What this means to users with these type of systems is that their installations do not meet the requirements of BS 5304.

The standard states that: "The arrangement of the pull-chord system should be such that it operates the associated switching device if either the chord is pulled in any direction, or the chord breaks".

In contrast the approach that Guardmaster advocates, namely two switching devices or one device and a tensioner spring (Fig 2) does meet the requirements of the standard fully.

Guardmaster has many years experience of manufacturing and applying rope systems, including the company's Lifeline 4 product, which with its unique LRTS tensioner, provides safeguarding up to 75 metres.

Guardmaster is happy to give customers the benefit of this experience by offering advice for the correct installation and use of rope operated emergency grab wire systems.

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A Pro-talk Publication

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