... converting motors.II. The electric control system of the tower crane adopts the advanced PLC + frequency converter control mode ... the government for many consecutive years.Our main products are Tower Cranes (3T-25T, stationary, mobile, outside-climbing, inside ... , hammer-head, flat-top, multi-speed, stepless-speed), Construction Elevators(multi-speed, stepless-speed), Concrete Mixers (rotary-drum-type ...