Fig. 4 (above) shows the front of the cylinder. The sleeve valve (15) doubles as the guide for the poppet valve stem (12). When the sleeve valve rotates it aligns slot 16 with 3 for exhaust and 16a with 4 for intake. Fig. 5 (below) shows the assembled mechanism. A link rod (36) activating a bell crank (33) engages it with a geared plate (17) fixed to the sleeve valve to rotate the valve in time with a poppet valve, which is mechanically actived on exhaust by a finger (31).
Illustration courtesy Gas Engine Magazine