There are two categories: passive braking and active braking. An active brake is one that must be actuated and used by the rider of the zip line. A passive brake is one that engages and brings the rider to a stop without them needing to do anything. Proponents of active brakes often say that giving riders more control over their speed enhances their experience and enjoyment of the ride. Active brakes also tend to be easier to setup and can be used for a broader range of zip line applications than most passive systems. On the other hand passive brakes are generally considered safer, especially for younger or less competent riders who may not have the skills necessary to activate the brake and bring themselves to a stop prior to the end of the zip line.
The most common active zip line brake is a leather glove worn on the participant’s hand and used to push down on the zip line cable and create friction, slowing the rider down. Proper training and practice is necessary for a rider to know how to safely bring themselves to a stop.
The BrakeHawk utilizes a patent-pending design that clips onto the Rogue, Petzl Tandem Speed, Petzl Trac, and Petzl Trac Plus trolleys. This active braking device is great for both backyard and commercial zip lines, as it keeps hands free of the cable and puts the power of braking firmly in the hands of the rider. The rider engages the brake by pulling down on the BrakeHawk and creating friction between the zip line cable and the BrakeHawk brake pad.
Passive zip line brakes are essentially speed-reduction systems that require no input from the rider. In other words, a passive brake will stop a rider even if they are freaking out and unable to stop themselves. There are several types of passive brakes, so we’ll run through a few of the most common and explain how they work.
The bungee brake utilizes a padded block that mounts on the cable near the end of a zip line and slides freely up and down the line. A length of bungee cord (usually 20’ or more) is connected to the block and then strung out to a nearby anchor such as a tree or post. The rider’s trolley will impact the block and push it down the cable, stretching the bungee cord until all of the momentum is absorbed. The bungee will then retract, bringing the rider back to the low point on the cable where they dismount. This method is very common and practical for most backyard zip lines, but the retracting bungee makes it unsuitable for most commercial applications where the dismount is on a platform at the extreme end of the zip line.
A spring brake operates much like a bungee brake, but without the need for an anchor off to the side of the zip line. The spring compresses, absorbing the inertia of the rider, and then pushes the rider back out. Some higher end commercial zip lines utilize multiple springs, and the impact pad has a one-way cam that prevents the spring from pushing back out until the rider has been unclipped. Springs are typically not used in residential settings, due to the higher cost and the shorter braking distance when compared to a bungee brake.
Auto or wheel-barrow tires can be used as a braking method when a zip line has little to no speed at the end. The stopping distance is only as big as the diameter of the tire, so it’s really not as much about slowing you down as it is about protecting your equipment on impact and creating a no-pass barrier on the cable. This is very common for over-water zip lines where riders should not be allowed to pass a certain point and risk landing in shallow water. Tire brakes also provide an effective back-up for a bungee brake, ensuring that the bungee is not over extended and preventing riders from hitting the anchor even if the bungee were to fail. A Cable Clamp should be placed behind the tire to prevent it from sliding.
A capture block operates similarly to a bungee brake, except that instead of bungee cord, a rope is attached to the block, and friction is applied to the rope to absorb the rider’s inertia. No recoil. It is also common for the block to ‘capture’ the trolley to allow for the rider to be towed in the rest of the way in case he or she stopped too soon. This could technically be called an active brake because the friction is applied manually by a guide, but it still acts independently of the participant. This method is used almost exclusively by commercial locations with trained guides, and boasts one of the best through-put rates (riders per hour), lowest number of rescues (people who don’t make it all the way across and have to be retrieved), and most dynamic braking resistance (guides can instinctively apply the necessary amount of friction to match the rider’s weight and momentum).
A gravity brake is basically… no brake at all. A zip line cable can be tuned in such a way that a rider will not have enough momentum to carry them to the end of the zip line. This can be achieved through a large amount of sag (lots of uphill cable at the end), or reducing the overall drop of the cable end-to-end.