Installation of a hydraulic kiln drive to eliminate a resonant vibration problem

Large dual electromechanical drive systems have been shown to often experience vibration problems due to both the high inertia of the components of these systems, and the large number of resonant frequencies experienced by these drives. Hydraulic drives, by comparison, are extremely low inertia drives, that have fewer resonant frequencies and benefit from the damping characteristic of the hydraulic oil used to transmit power. Additional benefits include the ability to isolate components while operating the drive and smooth speed control starting at extremely low speeds and full rated torque. This paper outlines the vibration problems that were experienced in a dual drive of a 655' long with 22' and 19' diameter section rotary cement kiln between 1979 and 1993. A number of analytical and empirical studies were performed and various modifications were made or considered to reduce the vibration in the drive train. Finally, in 1994 when the existing drive reached the end of its life, it was replaced with a hydraulic system. The methods both used and considered to reduce the vibration are discussed, as well as the critical elements in deciding on a hydraulic drive and the design issues encountered including questions of drive efficiency, reliability, maintenance and control. Results to date of the hydraulic drive are discussed, including the elimination of the vibration problem and added flexibility in speed control.