Tie down with automatic strap tension adjustment
View Patent ↗A tie down apparatus wherein a center leg of each of a pair of load springs is mounted in the space between a pair of drum pins, which space receives and holds a tied down strap. Each load spring is fixedly attached to a respective one of first and second ratchet wheels and a circular plate is positioned within each ratchet wheel and configured to rotate through a selected arc with respect to each ratchet wheel to limit the pre-load applied to the load springs.
1. A method of providing strap tension adjustment for a tie down apparatus comprising:
providing a rotatable drum surface configured to wind up a tie down strap and having a slot therein configured to receive the tie down strap;
providing a ratchet wheel comprising a plurality of ratchet teeth and having an interior opening with at least one inwardly protruding nub positioned thereon;
mounting a spiral load spring having an outer tab and an inner leg adjacent the ratchet wheel;
causing the inner leg of the spiral load spring to rotate in unison with said rotatable drum surface;
causing the outer tab of said spiral load spring to rotate in unison with said ratchet wheel so as to load said spiral load spring;
causing a nub engaging surface to rotate in unison with said rotatable drum surface within said interior opening of said ratchet wheel so as to come into engagement with said inwardly protruding nub as said ratchet wheel rotates such that the engagement between the inwardly protruding nub and the nub engaging surface terminates loading of said spiral load spring.
2. The method of claim 1 wherein termination of loading of said spiral load spring limits an amount of pre-load force applied to said spiral load spring.
3. The method of claim 1 wherein the interior opening of the ratchet wheel comprises a circular surface on which said nub is formed.
4. The method of claim 3 wherein said plurality of ratchet teeth are circumferentially disposed around an outer surface of said ratchet wheel.