Abstract: A device and method of operating a diaphragm pump having at least three chambers is used in a vapor compression refrigeration system. Each chamber contains a fluid having a different set of pressure and temperature characteristics. Adjacent chambers are separated by movable barriers, such as flexible diaphragms or pistons, that are sequentially moved by pressure changes resulting from heating and cooling the fluids. The fluids are chosen so that driving fluids operate in a substantially narrower temperature range than a working fluid but have the same operating pressure range permitting use of a thermal energy source having a selected temperature to power the pump. Optimal selection of both driving fluids and the working fluid permits use of a low grade heat source for thermal energy.

Abstract: The attachment device is made of two piece separable construction for use in securing flexible films and fabrics, hereafter referred to as material. One element has two longitudinal grooves facing in opposite directions, one groove being larger than the other groove. The other element has two longitudinal beads that positively interlock with the grooves of the first element when the two elements are pushed together by one of said beads and the larger groove acting as a pivot and the other bead and smaller groove being engageable by relative rotational movement of said elements about said pivot. Flexing of one or both elements allows for engagement of the shallower groove and complementary bead. The said interlocking action of the two elements is utilized to capture and secure material placed between the two elements. The shallower groove and complementary bead are disengageable by relative rotational movement of the two elements about said pivot when the two elements are pulled apart.

Abstract: Hinge mechanism for locking the two foldable sections of an extension stepladder in spread-apart position. Each section has a locking pin and slot at its upper end for interlocking with a complementary slot and pin on the other section when the sections are swung apart on one of said pins as a pivot, the pin and slot on one section being disengageable from the slot and pin on the other section by relative longitudinal movement of the sections when the sections are folded together.