This past summer was debatably the worst period of my life. I have had my fair share of rough patches in life with parents divorcing (multiple times), a chronic kidney disease, and a seeming magnetism of sports balls to my face. Despite all that, I honestly never felt more lost, hopeless, or, quite frankly, apathetic. However, there is always a silver lining to these sorts of things. I picked up a new hobby! Technically, a friend of mine introduced me to climbing about three years ago, but I never got too into it because life, primarily school, got in the way. So, this July I picked it back up again as a way of getting my mind off of things and keeping me in shape, a two-for-one deal! I have found I have a natural affinity for climbing in a couple of ways. Despite being short, I have got lanky arms. I am a hopeful guy, which helps with the literal leaps of faith sometimes involved. Lastly, I don’t do terribly well with letting go. That one is sort of self-explanatory.
With the personal exposition out of the way, I’d like to introduce the Baffling Bob of the week: the auto belay. Traditionally, a belayer is not a machine but a person. For safety purposes, a climber will wear a harness that is hooked up to a rope that is wrapped around a pulley at the top of a climb. The belayer takes up the slack of the rope as the climber ascends and is ready to pull the rope taut if the climber falls off the wall. But what if you don’t have any friends or want to climb solo? That is where the auto belay comes in.
You can think of an auto belay as a huge tape measure with some added features. Auto belays are situated at the top of a climb and automatically take up the slack of the rope as the climber ascends using a coiled spring, the same way that a tape measure does. But this spring isn’t nearly enough to stop you from careening down to your doom in the event of a skill issue. There are two main types of auto belay on the market today. One is purely mechanical and uses a drum brake system, and the other uses magnets. Since we have already discussed DC motors before, I am going to elaborate further on the magnetic type.
The magnetic auto belay contains a non-magnetic metal disk that the rope is attached to. This metal disk is surrounded by magnets. When there is no velocity caused by pulling on the rope, there is no interaction between the metal disk and the magnets. However, when a climber falls, the disk rapidly speeds up since the rope rotates the disk. When the disk rotates and passes through the magnetic field of the magnets, circular currents of electricity are generated in the disk called Eddy currents. Circular currents of electricity generate their own magnetic fields. These magnetic fields oppose the magnetic field of the magnets. This creates a “magnetic friction” without the need for contacting parts. Cooler still, the braking force generated is directly proportional to the velocity of the metal disk, so the braking effect will be experienced the same for a full-grown adult or a child, regardless of weight. This is the same principle used in modern roller coaster braking systems. While there is no substitute for a trusty belaying partner anywhere outside of a climbing gym, auto belays are a great solution for many recreational climbers. Regardless of how you climb your way through life, safeguards like these remind us that sometimes the best option is letting go. You can always try again!
“The auto belay moments away from preventing my ass going to grass.” Kevin Castner Jr. for The Stute
