Abstract: A lock system for releasably locking a first component, pivotally coupled along a pivot axis to a second component, in a plurality of positions fixed relative to the second component. The system includes a first engaging mechanism fixed to the first component and aligned with the pivot axis such that it rotates in a rotation plane substantially perpendicular to the pivot axis when the first component is pivoted relative to the second component. The system also includes a second engaging mechanism pivotally mounted to the second component and movable between a first engaged position in which the second engaging mechanism fixedly engages with the first engaging mechanism, preventing the first component from pivoting relative to the second component, and a second disengaged position removed from the first engaging mechanism wherein the first component is free to pivot relative to the second component.