US Patent 7628561 Head clamp releasable locking device

A device for positioning and locking a head clamp in a selective position including a first arm, a second arm and a third arm. The third arm having a free end including both a spherical member carried in a socket and including a mounting tube and a gripping device to restrain movement of said spherical member. The head clamp includes a mounting post for insertion to said mounting tube wherein said mounting tube includes a releasable locking device for engaging and holding said mounting post against rotation and withdrawal of said mounting tube to prevent accidental release of the mounting post.