3-ring release system
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The 3-ring release system is a parachute component that is widely used by sport parachutists to attach the two risers of a main parachute to the harness that bears the load under the parachute.
Invented by Bill Booth, the three-ring system allows a parachutist to quickly release a malfunctioning main parachute with a single motion. Parachutists usually need to do this quickly during emergencies in which they need to deploy a reserve parachute. The three-ring system is simple, inexpensive, reliable, and requires less physical force than other parachute release systems.
The large bottom ring is securely attached to the harness which bears the parachutist's weight, and is connected directly to the riser by the middle ring and riser cloth, which is in turn held by a small ring & riser cloth. The small ring is secured by a cord loop, through which a cable runs holding the whole assembly in place. Releasing the cord loop by removing the cable with a tug causes the three-ring system to cascade free and quickly disconnect the riser from the harness.
Each ring in the series multiplies the mechanical advantage of the loop of cord that is held in place by the semi-rigid cable (a Lolon-F or Teflon coated steel cable, depending on manufacturer).
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[edit] Variations
There are a few different variations of the 3-ring system. The original 3-ring release from the late 1970s is now known as "large 3-rings". A version using smaller rings("mini rings") was introduced in the 1980s. The reasons for the development of the mini ring system and the associated smaller risers were mostly aesthetic; the mini rings do not increase safety but actually reduce the mechanical advantage inherent in the system thereby increasing the pull force a jumper must apply to cutaway. Tandem systems still use rings that are even larger than the original rings. Other variations have placed the rings under the risers facing back instead of forward of the risers facing front. The latest variation is the "Miniforce" system developed by Aerodyne International. It combines smaller rings with an improvement in mechanical advantage over other mini ring systems using an elongated middle ring. Some tandem rigs use four rings (e.g. Advance Tandem by Basik).
[edit] Safety Concerns
Since the introduction of the 3-ring system, variations in the design have raised safety concerns. For example, the move to mini rings and mini risers caused riser failures on some designs until riser strength was improved. The failure of some manufacturers to include stiff riser inserts to allow the free movement of the cutaway cable when risers are twisted has caused difficulty in cutting away from malfunctions with riser twists. The tolerance in the manufacture of the fabric risers and their connection to the rings is critical in maintaining the mechanical advantage of the 3-ring system and this has been compromised in some designs. Reversed risers placing the rings under the risers has prevented the rings moving freely and releasing under some cutaway scenarios.
[edit] Maintenance
Regular maintenance of the 3-ring system and risers is essential. Manufacturers recommend that the risers be disconnected from the harness and flexed, the rings should be checked for cracks or corrosion and the cable should be removed from the housing, cleaned and lubricated, typically with silicone based lubricant.
[edit] External links
- Relative Workshop 3-Ring Page — Relative Workshop's guide on correct 3-ring configuration.
