① Twin shafts mixer: Due to the twin shafs mixer’s mixing arm is short with lubrication system, it is assembled with a hydrostatic starter, so it can start the main motor when full loading materials. During working, usually it requires the mixer to start up under abnormal conditions . The twin shafts mixer has low noise and has good overload protection design, which is good for maintenance .② Single shafts mixer: The single-shaft mixer can also be started when full loading materials. The single shafts mixer adopts chain transmission structure which increases the wearing parts and generates additional vibration . Because of the existence of wearing parts , the maintenance cost is very high .