Abstract: Normally, spring loaded trip mechanisms increase in resistance and pressure as they move rearwardly. This device includes a swing arm above the shank with a roller engaging the upper surface of the shank. The tension springs extend from the swing arm to the upper end of the shank arm near the pivot thereof to the frame and are adjustable so that the initial tripping pressure may be set. Once this pressure is reached, the shank and arm move rearwardly causing the roller and swing arm also to be forced rearwardly thereby extending the springs. The geometry of the swing arm and springs, together with the shank is such that once the tripping pressure is reached and the shank commences to move rearwardly, the resistance drops rapidly instead of increasing thus letting the arm clear the object without any increase of contact force. Once cleared, the springs return the shank to the working position.