Front View	Side View

The Spiral Brake was invented by Lorin Bolinger and is described in the 1963 Speleo Digest. Lorin’s spiral brake was made from 10 gauge mild steel tubing, and he formed the ends to provide a smooth contour for the rope to pass. I used heavier 1-1/2 inch galvanized steel pipe, decided that I wasn't serious about using this device too often, and so just filed the edges enough to live through a few test rappels on a sacrificial rope. I treated the spiral brake to a corrosive salt solution to give it a used look, then took it out to test. As expected, the helical rope path causes me to spin extensively. On the plus side, the large mass, large contact area and low radius of curvature keep the device cool, and except for running over the ends of the pipe, the bending stress on the rope is minimal.

Despite the ease of manufacture, the spiral brake is far to heavy to take seriously.