Drive Train

Designed and machined by Rob Wallace this supercharger was fitted to the Borgward engined sports coupe, boosting its power significantly, until it finally blew up.

CAD/CAM was not available in the 1960s, so the cycloidal curve profiles of the lobed rotors were calculated from manually derived equations. Neither had calculators become available, so the X-Y coordinates of every point on the curve had to be calculated using 5 figure logarithms.

The aluminium castings were machined on a standard milling machine, the longitudinal and transverse table movements being made manually in small increments, from the calculated co-ordinates. Precision was essential to ensure close clearances, requiring accurate synchronizing of the two rotors rotating in opposite directions, coupled together by helical timing gears. Axial adjustment of one helical gear on its shaft provided a simple method of synchronization.