Abstract: The poppet trip device of the present invention is adapted for hydraulic cylinder units having a poppet axially movable within a poppet sleeve extended through the piston of the hydraulic cylinder unit. A head end of the poppet extends outwardly from the piston for engaging the head end of the cylinder in response to movement of the piston to the cylinder head end whereby the poppet is unseated and fluid communication is established through the poppet sleeve. Since the piston is spaced from the free end of the piston rod, however, engagement of the piston rod with the base end of the cylinder leaves the base end of the poppet spaced from the cylinder base end. The trip device or contact member of the present invention therefore is supported between the cylinder base end and piston for engaging the base end of the poppet in response to movement of the piston rod to the cylinder base end whereby the poppet is unseated and fluid communication is established through the poppet sleeve.

Abstract: An oscillating fluid-driven actuator for a shaft, such as a ship rudder shaft, a butterfly valve spindle or the like. The actuator comprises (i) a stationary actuator housing defining an annular chamber coaxial with the shaft and having a suitable cross section, and (ii) an annular piston arranged coaxially with the shaft in the chamber and connected fixedly with the shaft by means of an arm mounted intermediate the ends of the annular piston by means of a central piston hub. The piston hub is made with a coaxial bearing surface or surfaces of convex spherical shape and the actuator housing has a central lower hollow hub defining an inner concave spherical bearing surface to support the piston hub by engagement with the spherical surface thereof. A corresponding concave spherical bearing surface is arranged in the upper portion of the housing to cooperate with the corresponding spherical surface of the upper portion of the hub.