Tree climbing and arborist work are fields which have their own jargon and technical terms. Books, catalogs, and web sites having to do with tree climbing and tree climbing gear will use many terms and abbreviations, the most common of which we will define here. These definitions are not meant to provide instruction in any way, but merely to be used as a reference. If there are terms you would like to see added here, please contact WesSpur.
Average Breaking Strength. Some manufacturers of rope or hardware supply an Average Breaking Strength (ABS) for their products, which is the average applied force at which the rope or device fails. Factors such as shock loading will exert many times the weight of the load in force on the tree gear in question. If you know the Average Breaking Strength for the gear in your system, you can calculate a Working Load Limit (WLL) appropriate for your gear.
Example: Samson Stable Braid 1/2" Rope has an average breaking strength of 10,400 lb.
See the definition for ABS above.
See the definition for Friction Saver below.
This term describes the doubling of force exerted on the suspension point in a rigging or climbing system (tree limb, block, etc.) when a load is suspended on a rope running over a suspension point. An equal amount of force must be applied to the other end of the rope to keep the load from moving. The suspension point carries double the weight of the load on one end of the rope. This applies to rigging systems and also SRT climbing systems.
A suspension point in a tree other than a natural crotch created with the use of slings, pulleys, friction savers or other devices. The use of a false crotch has advantages for both tree rigging and tree climbing systems. False crotches can be installed on any structurally sound portion of the tree, freeing the tree climber from being dependent on the natural limbs or crotches of the tree for use as the suspension point. Running climbing or rigging ropes through hardware protects both the rope and tree. The use of a false crotch is necessary in negative blocking.
A flipline is a type of work positioning safety lanyard which gets its name from the way it is "flipped" up the tree while spur climbing. Sometimes also called a "scare strap" or "safety". Fliplines are used to secure the climber to the trunk of the tree while climbing with spurs. Fliplines may have a wire-core for added protection from a chainsaw. ANSI standards for safety in arboriculture require the use of two connections to the tree while cutting, of which a flipline is often one.
Also called Cambium Savers or Rope Savers. The Friction Saver is a device which wraps around the limb or crotch in the tree where a rope will run. The rope then runs either through rings at the end of the friction saver, or through the center of the rope saver depending on the style of device. This protects the rope from abrasion and also protects the tree from the friction of the running rope. Friction savers are used to create a false crotch in tree climbing.
Natural Crotch is the term used for the crotches in trees where branches meet the trunk. These can be useful places to install a climbing or rigging line, though both the rope and tree will experience more abrasion and wear, and they may not be located in ideal places. Compare to to a False Crotch.
This term is used to describe rigging in which the arborist block is installed below the trunk or limb to be removed, such as in butt-hitching during removals.
See the definition for Friction Saver above.
Shock loading is the term used when a rope system or rigging device has a sudden load applied to it, usually by catching a falling object. When a device is shock loaded, a much greater force is applied to it than the weight of the object being caught. The farther the object falls, the greater the force applied. This force is many times the weight of the object. This is why it is important to stay within the Working Load Limit of the tree equipment being used.
Example: Butt hitching is an application where the rigging system will experience shock loading.
SRT stands for Single Rope Technique and describes a rope climbing system in which the climber ascends a single leg of the rope, while the other leg is anchored.
Spurs is one of the most common terms for the spiked climbing tools worn on the leg by tree or pole climbers. Also sometimes called "Climbers", "Hooks", "Gaffs", "Irons", or "spikes". Tree climbing spurs are typically fastened at the ankle with a synthetic strap and around the calf with a second strap which runs through a pad. "Gaff" is the appropriate term for the spike portion of the climbing spur. A set of climbing spurs is used with a tree climbing harness and a flipline.
Working Load Limit. See Working Load Limit below.
Working Load Limit (WLL) is the maximum weight that the product is intended to handle safely. This is a percentage of the product's Average or Max Breaking Strength. The ANSI Z133 standards for arboriculture outline Working Load Limits at 10% of ABS for Textile products and 20% for hardware.
Example: An arborist block with 40,000 lb. breaking strength will have a working load limit of 8,000 lb. at 20% of the breaking strength.