| The Frode Rotary Valve |
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| Above is shown the rotary valve for a 125cc racing motorcycle engine, sectioned along its axis. The cylinder for the engine, partly shown, is leant over to the left, and the piston is shown at TDC. This valve was driven at constant speed from the crankshaft, at 1/4 crankshaft speed. Although successful in racing when introduced, its maker and sponsor company NSU failed financially, and the valve type has not been made since. |