Hydraulic boom stop

Abstract

A hydraulic boom stop for a crane that permits operation at angles greater than the normal maximum operating boom angle of the crane boom. The hydraulic boom stop has at least one hydraulic cylinder and a hydraulic control system that is user controlled. The user controls the hydraulic fluid pressure to a boom control valve that in turn regulates the movement of the boom. As the hydraulic cylinder ram moves, the hydraulic fluid displaced by the ram provides a back pressure in the boom control valve that opposes and slows the continued upward or downward movement of the boom. The back pressure bleeds off through restricting valves in the communication lines. A relief valve in communication with the line associated with the inward movement of the ram releases the pressure in that line when it attains a predetermined value. In this way, the ram movement is less rigid and the hydraulic cylinder acts as an effective damper of impact forces. The user also controls the outward movement of the ram. Thus, the hydraulic boom stop acts as a kick-out device. Indicating devices, such as a horn, are included to indicate operation of the crane above the normal maximum operating boom angle of the boom.

Dependencies are inferred from the claim text.