Abstract: A locking mechanism for the elbow swivel joint of a support arm for selectively locking the lower arm section and upper arm section of the support arm relative to each other, in which the lower arm section has a swivel head positioned between the end flanges of the upper arm section. A carriage bolt runs through centrally-located coplanar screw holes in the swivel head and end flanges for completing the live hinge of the swivel joint elbow. The locking mechanism preferably includes three spring-biased locking pins that sit in three open-ended guide channels in the relevant end flange of the upper arm section, and there are also a plurality of corresponding locking pin receiving notches on the engagement surface of the swivel head, and a locking knob for compelling the three spring biased locking pins into mating engagement with the corresponding locking pin receiving notches on the engagement surface of the swivel head and holding them in place.

Abstract: A locking mechanism for the elbow swivel joint of a support arm for selectively locking the lower arm section and upper arm section of the support arm relative to each other, in which the lower arm section has a swivel head positioned between the end flanges of the upper arm section. A carriage bolt runs through centrally-located coplanar screw holes in the swivel head and end flanges for completing the live hinge of the swivel joint elbow. The locking mechanism preferably includes three spring-biased locking pins that sit in three open-ended guide channels in the relevant end flange of the upper arm section, and there are also a plurality of corresponding locking pin receiving notches on the engagement surface of the swivel head, and a locking knob for compelling the three spring biased locking pins into mating engagement with the corresponding locking pin receiving notches on the engagement surface of the swivel head and holding them in place.