Abstract: A gyroscopic apparatus (100), having application as a prime mover, comprises a pair of discs (102) disposed opposite one another with arms (104) rotatably supporting the discs (102) connected at a pivot point, the pivot axis thereof lying in a plane midway between the discs (102). A drive arrangement (124, 126, 180) operates to spin the discs (102) in opposite directions while simultaneously rotating the whole assembly of discs (102) and arms (104) about a second axis in the same plane as, but perpendicular to, the pivot axis. A camming arrangement (144, 146, 152) working in conjunction with the rotation about the second axis periodically forces the spinning discs (102) to pivot about the pivot axis to thereby generate a force along the second axis which can be used to perform useful work.