15,849. Andrews, T. M. July 13, 1905, [date applied for under Patents Act, 1901]. Fixed-abutment type.- A steam or other rotary engine, in which two piston drums 5, Figs. 1 and 2, are eccentrically mounted in cylinders 2, is provided with a rotary plug valve by means of which the engines may be reversed, or the supply of steam to the cylinders cut off. The drums are provided with piston vanes 6, 7, 8, arranged in diametrical openings 6 and jointed to carriers 12, which move in grooves in the ends of the cylinder and in the partition 2' between the cylinders. The vanes are preferably provided with spring-pressed packing-plates 14. Steam is supplied to each cylinder by an inlet 15, and leaves by an outlet 17, 17', or enters by an inlet 16 and leaves by an outlet 18, 18<1>, according to the direction in which the engine rotates. This direction depends on the position of a rotary plug, formed in two parts 40, 41, which are arranged in a casing 22 preferably lined with a shell, formed in two parts 28, 29 connected by a ring 30, Fig. 3. A series of ports are formed in the plugs 40, 41, and a series of apertures in the shells 28, 29, so that when the plugs are rotated by means of a handle 51 on a packed spindle 50, the steam-chest 26 is either cut off from the inlets of the engines, or is connected to the inlets 15 or 16. In either case, the admittance of steam to the inlets is controlled by reciprocating valves 19, which work in passages 21 connected to the chest 26 and open and close ports 24, 25 leading to the plugs 40, 41. The valves 19 are provided with extensions 20 which enter eccentric grooves 9, 10 in the drums, the maximum depth of each groove being at points equidistant from the vanes. The vanes of the two cylinders are arranged perpendicularly to each other. One valve 19 is open when the other is closed. The parts 40, 41 of the plug are spaced apart by a block held in place by rings which serve also as a packing. When the passage 15 is the inlet, any steam which is carried past the outlet 17 is conveyed to the escape pipes 32 by way of the passage 16 and ports in the plug 41 ; in the same way, when the passage 16 is the inlet the passage 15 also serves as an outlet.