Tom Pasco's 42cc Sleeve Valve Radial




Where to start? Well, this is a 42 cc, three cylinder, four-stroke radial engine employing gear and crank driven sleeve valves, similar to the Bristol radial engines of the WWII era. It was scratch built from solid metal by Mr Tom Pascoe of Yarm, England in 2003. The engine design was also conceived by Tom, using a basic layout similar to that depicted in the single cylinder sleeve valve drawing below--an earlier design of his. If you look at the detail long enough, you will start to appreciate just what Tom has accomplished as about the only "bought bits" I can spot are the fastners and the prop! Apart from the obvious, examine the gears, distributor, even the sparking plugs. Each piston and head are fitted with a Dykes ring. The sleeves are articulated by individual crank shafts geared from the main shaft. A ball joint is employed to accomodate the orbital motion of the sleeve around its driving pin.

For the curious, Tom is a retired tool and die maker. His engines are built in his home shop which is NOT CNC equiped. He has a Colchester Chipmaster, a Cincinnati mill, and a small pillar drill, all surplus from the company he owned and ran until retirement.

And finally, if you fancy a 5MB download, here's a video of the piston and sleeve motion as the engine is cranked over. We are indebted to Mr Ken Croft for taking all the pictures, and composing the video. At the time of writing (July, 2003), the engine has been successfully test run. Thanks Ken, I think...




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