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2. Steel erector’s life line

When working at height, steel erectors use a life line that holds them in case of a fall.

The problem is that if the life line is long enough, there is a strong jerk that can hurt a worker. Of course, the life line can be made elastic to soften the jerk. In this case, however, the effect of a ball on a rubber band will occur so a worker can hit himself against the construction elements.

Questions: How to protect a steel erector against a strong jerk of a life line without using an elastic cord?  

        • Stopped steel erector

        • A steel erector is stopped by a life line attached to his belt.

        • The steel erector is injured.

        • Construction elements, hook, belt, life line

        • Structural components hold a hook. The hook holds a life line. The life line transmits force to a belt. The belt stops a steel erector.

        • The belt stops a steel erector.

        • The life line pulls the belt strongly due to a backward jerk. A harmful product occurs – the injured waist of the steel erector.


        • Near the steel erector’s waist.

        • Immediately after the full stop of the falling worker.

        • Why does the belt strongly pull the steel erector?


          1. High falling speed before stop.
          2. The belt is rigid.
          3. The life line is rigid.
          1. Reduce the falling height.
          2. Make a soft harness like that of a parachute.
          3. Make the life line elastic.

          To implement the first two hypotheses, the device needs substantial transformation. Therefore, this can only be done on a new life line.

          Formulate the problem on the basis of the third hypothesis.

        • An elastic life line stops the steel erector falling. However, a backward jerk and the worker swinging occur, which should be eliminated.

          Question: How to eliminate the backward jerk of the elastic life line?

      • Selecting a problem model

        Model selection criteria: 

        1. If it is clear what conditions should be obtained in the conflict zone, choose the “Conditions in OZ” model; 
        2. If the condition is formulated as an action, choose the “Actions in OZ” model;
        3. If a technical contradiction is formulated, choose the “TC” model;
        4. If a physical contradiction is already formulated, choose the “PhC” model.

        “Physical Contradiction” model

            • The life line should be elastic not to cause a strong jerk.

              The life line should be rigid to hold the falling steel erector.


              • Around the hook, belt and life line

              • The time from the beginning of the life line stretching till the full stop of the steel erector.

              • 1.Hook 2. Life line 3. Belt 4. Steel erector’s body 5. Construction elements 6. 

                Readily available substance resources.

              • 1. Steel erector’s falling energy 2. Readily available field resources

            • Conflicting requirements can be separated in time.

              First, let an elastic line act. It will softly hold the worker and decelerate him during the fall.

              After softening the impact energy, the elastic life line should become rigid and strong to finally hold the worker.

            • Find such a design for a life line that would keep it elastic until a certain load is reached and make it rigid after the load is exceeded.

              1. Distort elastically under the weight of a steel erector until a certain limit is reached.
              2. Become rigid after reaching a certain load threshold.
              3. Not produce a backward jerk.
              4. Be lightweight. 

            • The life line or its portion is made from an easily deformable metal such as aluminum or soft steel. When the worker falls, the chain deforms, stretches with resistance and absorbs the impact energy. The stretched chain will finally hold the falling person.

            • The device is simple in design and application, works reliably and does not cause any additional manufacture- or use-relating problems.

              The disadvantage is that it is necessary to  attract resources from the supersystem.

              Continue problem solving using another model.

        “Actions in Operational Zone” model

            • An elastic life line smoothly stops a steel erector, but a backward jerk occurs.

              The disadvantage type: a too strong backward action.

              Imagine that the elastic life line is a model composed of small creatures.

              The small creatures are arranged in chain and each of them holds another one’s feet with its arms.

              They are strong enough, but keep their hands bent at the elbows to provide a smooth stopping of the falling worker. After the first jerk, they reflexively bend the hands and produce a backward jerk.


            • The disadvantage can be eliminated if the life line is weak and breaks under the load of a falling person.

              Use modeling with smart little creatures. Find out how they can help us.

              Let us draw a chain – a life line, let the creatures be weak and just release their hands at a certain load, thereby breaking the chain. In parallel, let us arrange another chain composed of strong creatures that in no case will release their hands.

              This is what we have:

              It won’t get you anywhere yet, the life line working conditions will not change. It seems that the functions of the two chains are different. The weak creatures should be first to operate, they hold the worker’s weight up to a certain limit and then release their hands and break the chain. Only after that do the strong creatures come into play.

              It may look as follows:

            • Introduce an X-component into the system that is arranged in parallel to the life line and breaks under a certain load.

              1. Hold the load until a certain value is reached and then break.
              2. Be lightweight.
              3. Be inexpensive and readily available (made from the belt, life line or hook).

            • The X-component is a thin breaking line, cord.

              The main line is folded and stitched with a thin breaking cord. When a worker is falling, the cord breaks and smoothly reduces the worker’s falling speed.


            • The device is simple in design and application, works reliably and does not create any additional manufacture- or use-related problems.

      • The main line is folded and stitched with a thin breaking cord. When a steel erector is falling, the cord breaks and smoothly reduces the worker’s falling speed.