The U.S. Navy is using a new vibration-proof fastening system designed to dramatically reduce maintenance and improve performance of its Hovercraft, also known as the Landing Craft, Air Cushion (LCAC).
The ship is used by the U.S. Marine Corps to transport supplies, vehicles and troops to the shore from a Wasp class assault ship or other amphibious vessel. They can travel at up to 40 knots (46 mph) and can be mounted with two machine gun emplacements and 40 mm grenade launchers.
They have been slowed in the past by damage to 100 rubber-pleated skirt pieces that fit to their lower portion. The previously used fasteners had to be removed with bolt cutters. Additionally, a 2-ft section had to be replaced even though only front sections were torn. “It is a very time-consuming and laborious task for the Navy personnel and requires them to climb under the Hovercraft,” says Loren J. Ball, CEO of Permanent Technologies of Hauppauge, NY.
In the new design, a replaceable rubber section in the front of the pleat is attached with 22 Tine-Lok fasteners that can be removed with regular tools. “The time savings is huge and they believe that the skirts will be repaired more often since it is not a major production as in the past,” says Ball. Each Hovercraft will use 7,000 to 10,000 Tine-Lok Fasteners.
The Tine-Lok nut has one or more tines that work in conjunction with longitudinal bolt thread channels to prevent counter rotation and loosening. The number of nut tines and the number of bolt channel locks vary based on vendor specifications. They can be made from many different metals, ranging from stainless steel to proprietary alloys. The Navy asked Ball to explore the feasibility of meeting specifications with a molded plastic version.