adapted to straddle the keel bone k of the poultry carcass the swivelling cutting assembly 150 is sized and positioned so that the rotary cutting blades 173 and 175 are positioned adjacent and below the tunnel assembly 96 as the lower flight 15 of the conveyor system moves in the lower direction as depicted by arrow 177 the rotatable shaft 154 is driven as follows see fig3 teeth 178 mounted to the conveyor system 12 engage sprockets 179 and 180 mounted on a power takeoff shaft 182 thereby causing the sprockets and the power takeoff shaft to rotate shaft 182 drives a large sprocket 183 which in turn drives a first power transmission chain 184 as the lower flight 15 of the conveyor system moves in the forward direction of the arrow 177 the sprocket 183 and chain 184 are driven in the clockwise direction of arrow 186 the clockwise motion of chain 184 is used to drive a small sprocket 187 in a clockwise direction the small sprocket 187 is rigidly mounted to the axle 153 which also carries a second small sprocket 189 the small sprocket 189 drives a second power transmission chain 191 which in turn drives a driven.