15,433. Ennis, J. G. July 4. Gas and like engines, reversing. The invention relates to reversing four-stroke-cycle road vehicle and marine engines and consists in utilizing the initial reverse rotation of the crank-shaft to ad just both the valve-gear and the ignition mechanism automatically to suit the altered conditions of running. The engine is first slowed down by cutting out the ignition ; failing to pass the dead-centre on the final compression stroke, it recoils and completes an auxiliary ignition circuit which fires the compressed charge and gives the piston its initial impulse in the opposite direction. The reverse rotation of the crank-shaft having adjusted the valve-gear, normal running is established. The distributing-valves 6, 7, Figs. 1 and 7, are operated by cams 8, 9 and act either as admission or exhaust valves in accordance with the direction of running. The chambers 22, 23 have each three controlling- valves, those shown in the chamber 22 at 6, 24, and 26 regulating the cylinder port 14, the mixture inlet passage 16, and the exhaust port respectively. With the engine running in the direction shown in Fig. 1, the products of combustion exhaust through the chamber 22 while the adjoining chamber 23, with its closed exhaust valve 27, admits explosive mixture through the inlet valve 25 and the cylinder admission valve 7. The normally stationary mixture-admission and exhaust valves 24, 26 and 25, 27 are operated in pairs so that the admission valve of one chamber opens simultaneously with the exhaust valve of the other. The valves are permanently adjusted by levers which receive motion from the shaft 45, through rods 40, 41 and the wrist plate 39. The shaft 45 is adjusted, when starting, by the hand lever 49, and when reversing by the backward movement of the crank-shaft. The wrist plate 39 which is mounted on the shaft 45 is engaged by a pin carried by a crank 69, Fig. 2, on the end of a shaft 56. Carried by the shaft 56 is a pair of longitudinally adjustable trip levers 57, 58 the movements of which to reverse the valve gear are controlled by cams 50, 51 driven from the cam shaft 53. The hand-lever 65, Fig. 2, which throws the trip-levers into the path of the cams 50, 51 also closes the ignition circuits shown diagrammatically in Fig. 4. The auxiliary circuit 97, 98, 99, 96, Fig. 4, is completed by the end of the trip-lever 57 engaging with the contact-strip 96. This circuit is broken and the normal circuit established when the lever 57 reaches the contact 92.