Self Retracting Lifelines

Also called an SRL or yo-yo, the self retracting lifeline is a piece of fall protection equipment that is commonly used in the construction industry. In the event of a fall, an SRL senses the speed of movement, and stops the fall within as little as a few inches.

The self retracting lifeline is attached between the anchor point, which may be an overhead beam for instance, and the back d-ring of the workers full body harness. The SRL then allows the cable or webbing to play out in response to worker movements.

The best way to describe it may be to think of a seat belt. As we move or lean forward, the seat belt webbing moves more or less freely, with a gentle spring tension at all times. In response to a quick tug or sudden stop we have all felt the seat belt jerk taut. This is essentially what an SRL does.

As a further refinement, and also similar to a seat belt, there is a built in shock absorbing feature. Even though there might be a lot of force, or energy, involved in a sudden stop, we generally do not feel the brunt of it.

This is because some controlled amount of stretch absorbs a portion of the impact energy. In fact, OSHA requires that we keep this impact force to 900 lbs. or less. That may sound like a lot, but without this braking action, that force may easily be 4 or more times that figure.

In general, a ‘straight’ fall that involves the use of an SRL is not really uncomfortable. We wouldn’t go so far as to say gentle, but a lot less harrowing than you might imagine. Indeed it is important to pay attention to the ‘straight fall’ aspect just mentioned. The common way we see workers misuse an SRL is to venture sideways relative to the overhead anchor point. So instead of gravity taking you straight down, the result is what is referred to as a ‘swing fall’. That is, when you fall, your body acts like a pendulum and may strike an object of some sort, thereby causing an injury.

The self retracting lifeline is an alternative to the standard fall protection Shock Absorbing Lanyard. These two items are not really equal, and they have applications where one or the other is best suited. Shock absorbing lanyards generally come in fixed lengths, with 6 foot being by far the most common. As the name implies, this type of lanyard incorporates a stretch capability to absorb or dissipate some portion of the direct impact forces. This is an OSHA requirement, and really are the only lanyards we sell for applications that may involve a fall.

A properly situated SRL (overhead) will arrest your fall in as little as 14 inches. By contrast, a shock absorbing lanyard (with its fixed length) must become taut before the fall arrest can begin. If the anchor point being used happens to be at or near your feet, you may have traveled up to 12 feet before the lanyard comes taut. The braking action (stretch) is allowed to be up to 42 inches further than that. You have now traveled almost 16 feet; How far away was the ground?

As you may be able to see, there are practical and mechanical differences between an SRL and a shock absorbing lanyard. Recognizing and understanding these differences should allow you to make better decisions about which fall protection connector to use.

We welcome your questions or suggestions, and if this explanation helped or hindered your understanding of What is a Self Retracting Lifeline?, we would love to hear about it. pks-store@pksafety.com