A tether is a cord, fixture, or flexible attachment that characteristically anchors something movable to something fixed; it also maybe used to connect two movable objects, such as an item being towed by its tow. Applications for tethers include:

fall arrest system Fall arrest is the form of fall protection which involves the safe stopping of a person already falling. It is one of several forms of fall protection, forms which also include fall guarding (general protection that prevents persons from enteri ...

lanyards A lanyard is a rope, cord, length of webbing, or strap that may serve any of various functions, which include a means of attachment, restraint, retrieval, and activation and deactivation. A lanyard is also a piece of rigging used to secure or ...

, balloons, kites, airborne wind-power systems,

anchor An anchor is a device, normally made of metal , used to secure a vessel to the bed of a body of water to prevent the craft from drifting due to wind or current. The word derives from Latin ''ancora'', which itself comes from the Greek ἄγ ...

s, floating water power systems, towing, animal constraint,

space walks Extravehicular activity (EVA) is any activity done by an astronaut in outer space outside a spacecraft. In the absence of a breathable atmosphere of Earth, Earthlike atmosphere, the astronaut is completely reliant on a space suit for environmen ...

power kite A power kite or traction kite is a large kite designed to provide significant pull to the user. Types The two most common forms are the foil, and the leading edge inflatable. There are also other less common types of power kite including rig ...

ing, and

anti-theft Anti-theft systems protect valuables such as vehicles and personal property like wallets, phones, and jewelry. They are also used in retail settings to protect merchandise in the form of security tags and labels. Anti-theft systems include devices ...

devices.

Failure

Failure mode Failure causes are defects in design, process, quality, or part application, which are the underlying cause of a failure or which initiate a process which leads to failure. Where failure depends on the user of the product or process, then human er ...

s for tethers are considered in their design. A cord or rope tether may reach its

breaking strength Fracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displa ...

and fail. Outcomes can include an injury or fatal fall, and damage or loss of life to personnel or bystanders caused by backlash of the ruptured segments. Failure-prevention may be designed into a tethering system. Some

safety harness A safety harness is a form of protective equipment Personal protective equipment (PPE) is protective clothing, helmets, goggles, or other garments or equipment designed to protect the wearer's body from injury or infection. The hazards a ...

es are used in combination with a shock-absorbing

lanyard A lanyard is a cord, length of webbing, or strap that may serve any of various functions, which include a means of attachment, restraint, retrieval, and activation and deactivation. A lanyard is also a piece of rigging used to secure or lower ...

, which has break-away stitching designed into it to prevent material failure and regulate

deceleration In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by the ...

, thereby preventing a serious

G-force The gravitational force equivalent, or, more commonly, g-force, is a measurement of the type of force per unit mass – typically acceleration – that causes a perception of weight, with a g-force of 1 g (not gram in mass measure ...

injury to the user when the end of the rope is reached. Designed-to-fail safety links are sometimes used to prevent excessive tension in a tether involved in towing objects, such as

sailplane A glider or sailplane is a type of glider aircraft used in the leisure activity and sport of gliding (also called soaring). This unpowered aircraft can use naturally occurring currents of rising air in the atmosphere to gain altitude. Sailplan ...

s. A signal tether is a system where a constant signal designates a positive condition, and its interruption, whether by discontinuation or jamming, conveys a failure. The signal may be electrically generated, or a physical device such as flying a flag.

References

{{tech-stub Hardware (mechanical)

Failure

See also

References