Generalize: Roots vacuum pump has a pair of tri-lobe rotors driven by a pair of high precision synchro-gears. The tri-lobe rotors finish one cycle of suction and discharge during 120 degrees. The tri-lobe rotors of involute profile rotate without contact and keep a constant gap in-between. It can be worked with various fore pumps by using air or water cooling mode and different sealing types in order to meet the various processing requirements and working conditions. Due to this patented design, our Roots vacuum pumps have obvious advantages over the traditional roots pumps of two-lobe rotors in the key performance indicators such as the pumping efficiency, maximum pressure differential, temperature rise, vibration and noise.