Patent ID: 8881566

Claim:
An apparatus comprising: a first disc and a second disc aligned with the first disc, a pivoting component configured to rotate about a pivot point, and a biasing member configured to urge the pivoting component toward the first and second discs; the first and second discs each comprising a generally circular circumferential surface and a recess configured to receive a locking bar; the first disc further including a first radial extension component forming a hook between a radially distant extent of the first radial extension component and the circumferential surface of the first disc; the second disc including a second radial extension component of a generally uniform width; the pivoting component including an arced surface that substantially mimics the radius of the circumferential surfaces of the first and second discs, a generally linear edge aligned with the first disc, and an extension aligned with the second disc; wherein the pivoting component is configured to prevent rotation of the first disc when the linear edge is engaged with the hook, and the second radial extension component is configured to interact with the extension to release the linear edge from the hook upon rotation of the second disc.