... the whole operation, reduce the noise, conserve the energy;c. There are 4 cutting edges in each rotary blade, revolve 90 °, it can ... be reused after damaged;d. There are 2 cutting edges in each stationary blade, revolve 180 °, it ... , operation smooth, low noise, high pulling torque;f. Materials are pushing by the hydraulic, independent motor system, stable structure, operation ...