What is a Sleeve Valve?

The sleeve valve was a popular alternative to poppet valves in internal combustion engines in the early to mid 1900s. The system utilized a ported, moving sleeve located between the piston and cylinder wall and rotated or moved up and down by a gear or camshaft driven actuators. The ports cut into the sleeve corresponded with inlet and outlet ports in the cylinder wall. The movement of the sleeve either aligned the sleeve and cylinder ports to allow for gas or fuel flow or blocked them off to seal the cylinder for compression and combustion. Notwithstanding this valve system's tendency to consume large quantities of engine oil, it did offer several noteworthy benefits over poppet valve systems of that era.

The sleeve valve was born in 1904 of dissatisfaction on the part of one Charles Yale Knight with the noisy poppet valve engines of the day. He set about inventing an internal combustion engine which featured a pair of sliding sleeves inside the cylinder which contained the piston. The sleeves were driven by camshaft operated connecting rods and slid up and down to align or close the sleeve and cylinder ports. Fuel and exhaust gasses were drawn in and forced out of the engine via these ports at the appropriate points in the combustion cycle. The “Silent Knight” engine proved to be quiet and efficient even if it was a prodigious consumer of engine oil.

Other engineers before long began to copy and improve on the sleeve valve design. The Burt McCollum design departed from the original in that it featured a single sleeve which combined the up and down action with a partial rotation of the sleeve. This design relied on a gear driven eccentric cam to provide the sleeve motion. Not only did the single sleeve setup improve the performance of the design as a whole but also largely cured the excessive oil consumption problem. The single sleeve valve was extensively used in large radial aircraft engines until the introduction of jet engines in the 1950s.

The sleeve valve system offered several distinct advantages over poppet valve equipped engines of the time. Volumetric efficiency was far higher due to the large valve ports which resulted in improved overall output and efficiency. The size of the combined port openings was also fairly easy to control at different engine speeds which made the engine more efficient across a wider revolutions per minute (RPM) range. The aerodynamic characteristics of the fuel/air entry and exhaust gas exit paths were also improved, thereby leading to additional improvements in performance. The lack of overhead tappets and cam assemblies also streamlined the engine's head design and thus making the whole assembly lighter and more compact.