Abstract: A cylinder deactivating device for diesel engines includes a rotary valve assembly operatively connected selectively to half of the cylinders so that half of the cylinders can be cutout when desired. The preferred embodiment includes a pair of separate rotary elements in the valve assembly which can be operated individually so that in an eight cylinder engine for example, it may be selectively adjusted to run on four, six or eight cylinders.

Abstract: A manual or automatically operated valve assembly is situated between one of the carburettor barrels and the intake manifold leading to four of the cylinders in an 8-cylinder engine or three of the cylinders in a V-6 engine. When open, the engine functions normally, but when closed, four of the cylinders are cut off from the carburettor so that the engine operates on only four cylinders. At the same time air intake ports open up so that a controlled amount of air is drawn into the inoperative four cylinders and exhausted through the exhaust valves so that these four cylinders will operate against a relatively low compression as well as acting as a vacuum breaker in order to stop oil pumping passed the piston rings. Control of the amount of air is by varying the size of these air intake ports.

Abstract: Each pair of piston and cylinders is twinned so that one acts as a primary or master piston and cylinder and the other as a secondary piston and cylinder. The pistons move in unison through the conventional four strokes of the Otto cycle. A transfer valve assembly is fitted into the head of the master cylinder and is ported to the secondary cylinder. It is adjustable so that it opens only when the power stroke is initiated and the pressure rises well above the compression pressure. When the transfer valve opens, the expansion takes place in both cylinders under any one of three conditions. (a) Inlet valve of the secondary cylinder is closed and sealed so that a vacuum is present as the piston descends.