Abstract: A self-propelled grass mower machine has a laterally projecting helically bladed cutter, a driving motor for effecting propulsion of the machine and driving of the cutter reel and transmission means for driving the cutter reel from the motor, the transmission means including a driven member, a transversely disposed driven shaft and universal couplings connecting respective opposite ends of the driven shaft to the reel and, adjacent the side of the machine remote from the reel to said driven member of the transmission means, the axes of the shaft and the reel being mutually inclined at a large obtuse angle.