Tree Climbing & Equipment Terms
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 equipment 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 add here, please contact WesSpur.
Breaking Strength -
The load rating at which a device will fail. Some manufacturer's of rope or hardware supply an Average Breaking Strength (ABS) for their products, which is the average load at which the rope or device fails. Others will provide a Maximum Breaking Strength (MBS). Keep in mind that factors such as shock loading will exert many times the weight of the load in force on the product. Example:
Samson Stable Braid 1/2" Rope has an average breaking strength of 10,400 lbs.
Compounding of Forces at the Suspension Point -
This term refers to the fact that if a load is suspended from a rope running over a suspenion point (limb of a tree, pulley, etc.), then an equal amount of force must be applied to the other end of the rope to keep the load from moving. This means that the suspension point carries double the weight of the load on one end of the rope.
False Crotch -
False Crotch is the term used to describe the creation of a suspension point for a climbing or rigging rope somwhere other than in a natural crotch. This practice protects both the rope and the tree. Example:
The False Crotch Rigging Kits can be used to create a false crotch rigging system.
Natural Crotch -
Natural Crotch is the term used for the crotches in trees where branches meet the trunk. These can be usefull places to install a climbing or rigging line, though both the rope and tree will experience more abrasion and wear, in comparison to a False Crotch. Example:
Tree Master 5/8" rope is a good natural crotch rigging line because of its ability to stand up to increased abrasion.
Shock Loading -
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.
Working Load Limit (WLL) -
Working Load Limit 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. Typical working load limits are often 10% or 20% of the breaking strength. Example:
A pulley with 20,000 lbs. breaking strength will have a working load limit of 2,000 lbs. at 10% of the breaking strength.
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