17,358. Lean, C. Oct. 1. Valves and valve gear.- Relates to steam engines, compressed-air engines, and the like, and has for its object the provision of means whereby the cut-off of the motive fluid may take place suddenly and certainly at high as well as at low speeds. According to the invention the cutoff valves are actuated by pistons subjected to the differential action of the pressures on opposite sides of the main piston, the moment of closure being determined by a trip or releasing mechanism under the control of the engine governor. Figs. 1 and 2 show in side elevation and plan respectively one form of the invention. In this, the four spindles 18 of the separate admission and exhaust valves at each end of the cylinder 1 are rocked invariably through connecting-rods 20 by the wrist-plate 17, which is worked by a rod 16 connected to a fixed eccentric on the engine crank shaft. Immediately beneath each admission valve is disposed one of the cut-off valves, which are operated by arms 44 connected by rods 42 to a sliding rod 31. On this rod are mounted two pistons to work in cylinders 29, 30, the outer ends of which are connected with the ends of the engine cylinder 1 by pipes 36, 37. It follows that, when one end of the engine cylinder is exhausting and steam is admitted to the other, the action of the cylinders 29, 30 is to tend to close the cut-off valves at once. This is prevented by latches or detents 45, 46, by which a block 49 fixed on the rod 31 is held until the release is allowed to take place under the control of the engine governor. When this takes place the cut-off valves close forcibly and suddenly, cushioning being effected in the cylinders 29, 30 by air enclosed in the inner ends which are open to the atmosphere through restricted passages. The cylinders 29, 30 may in other cases be made to cushion otherwise, as by the motive fluid acting on a differential piston. The release of the rod 31, and consequent closure of the cut-off valves, are effected by a reciprocating-rod 62 operated by a variable-throw cut-off eccentric combined with a shaft governor. The detents 45, 46 are pivoted in a fixed bracket 55 and are each furnished with a tail, the two tails being drawn together by a spring 58. The rod 62 carries a pin or tappet whereby it acts first on one tail and then on the other, thus releasing the detents alternately. The main and cut-off valves may be variously disposed with respect to each other in different modifications. The cut-off valve, for example, may be placed alongside of a combined admission and exhaust valve, or concentrically to such a valve, or to a separate admission valve. These modifications are each illustrated in the Specification.