Editing Zip line (section)

==Operation==
===Mechanism===
[[File:Departure zip SuperFly in Whistler, BC, Canada.jpg|thumb|Departure zip SuperFly in [[Whistler, British Columbia]], Canada]]

A type of pulley with a grooved wheel known as a [[sheave]] is used in zip-lines, and the pulley turns as it travels along, thus reducing [[friction]] and enabling greater speed than would otherwise be possible.<ref name=physics>{{cite web|url=https://adventure.howstuffworks.com/zip-line1.htm|title=How zip lines work: Physics of zip lines|first=Kate|last=Kershner|website=howstuffworks|access-date=23 January 2019|archive-url=https://web.archive.org/web/20180629022228/https://adventure.howstuffworks.com/zip-line1.htm|archive-date=29 June 2018}}</ref>

The zip-line trolley ("zipliner") is the frame or assembly together with the pulley inside that run along the cable.<ref>Some examples can be seen [https://zipline.systems/index.php/zip-line-pulleys-trolleys.html here].</ref> Zip-lines also have some kind of device to allow the cargo or rider to attach to the pulley system. This could include a harness, seat, a cabin or often just a handhold in smaller playground applications, that attaches to the pulley by a pivoting link or [[carabiner]] which secures the load, allowing the person or cargo to travel down the line.

====Braking====
[[File:Zip line spring braking system.jpg|thumb|Zip-line spring braking system]]

To be propelled by gravity, the cable needs to be on a fairly steep slope. Even then, the rider or cargo will often not travel completely to the end (although this will depend on the [[Structural load|load]]), and some means of safely stopping the car at the bottom end is usually needed with the larger zip-lines. Users of zip-lines must have some means of stopping themselves.<ref name=physics/> Typical mechanisms include:<ref>{{cite web|last1=Roper|first1=Aaron|title=Zip Line Braking Methods|url=https://www.ziplinegear.com/pages/howto-braking|website=ZipLineGear Knowledge Base|access-date=2 February 2015}}</ref>

*Friction created from the pulley rubbing against the cable
*Thick, purpose-built leather [[glove]]s
*A [[mat]] or [[net (device)|netting]] at the lower end of the incline
*A passive arrester system composed of [[spring (device)|springs]], pulleys, [[counterweight]]s, [[bungee cord]], [[tire]] or other devices, which slows and then stops the trolley's motion
*A "capture block", which is a block on the cable tethered to a rope controlled by a person who can manually apply friction on the rope to slow the user down
*Gravity stop, exploiting the sag in the cable, where the belly of the cable is always lower than the termination point. The amount of net incline in a zip-line system affects the speed at which the user arrives at the termination point.
*[[brake|Hand brake]] at the end of the zip-line

===Safety===
There are certain precautions that can be taken. Riders are physically attached to the cable by a [[safety harness|harness]] which attaches to a removable trolley. A [[helmet]] is required on almost all courses of any size. All zip-line cables have some degree of sag, so the proper [[Tension (physics)|tensioning]] of a cable is important and allows tuning the ride of a zip-line.