Abstract: A trough type solar collector or other body is mounted to rotate about a generally north-south pivotal axis. A balance weight is supported on an elongated heat sensitive beam anchored at its ends to the westerly side of the collector. The beam is adapted to bow away from the collector when it is heated by the sun's rays, thereby causing the balance weight to exert westward rotational force on the collector. A reflector may be positioned behind the beam to concentrate the sun's rays on the beam. A shutter is fixed to the collector to shade the beam when the collector is pointing toward the sun. Biasing means, such as a fixed weight secured to the easterly side of the collector, oppose the torque exerted by the balance weight and urge the collector to rotate eastwardly when the beam is unbowed. Damping means control the speed of westward and eastward rotation of the collector, and a pair of stops limit its westward and eastward travel.

Abstract: A bi-directional fluid flow control valve is provided with a spool-like valve body with a circumferential relief in its periphery bounded by a seal disk and by a reduced-diameter portion of the valve body, with a substantially tubular, elastic membrane stretched over the aforementioned portion and the seal disk, spanning the relieved portion. A flow channel penetrates the valve body centrally from the end closest to the reduced-diameter portion, and communicates with said relief via radial passages. Pressure differentials in either sense across the tubular membrane distort the membrane in such a manner that a flow passage is opened across the valve. When the pressure in the relieved groove is greater than on the outside of the membrane, the latter lifts from the seal disk. When the external pressure is greater, the membrane collapses into the relief groove, allowing flow through channels milled in the inner face of the seal disk.