1, the overall structure of the pump Roots vacuum pump pump body structure determines the structure of the overall structure of the pump. At present, Roots vacuum pump at home and abroad generally has three types of overall structure: (1) Vertical structure of the inlet and outlet level settings, assembly and connection of the pipeline are more convenient. However, the high center of gravity of the pump, poor stability at high speed, so this type is mostly used for small pumps. (2) horizontal pump inlet on the exhaust port in the next. Sometimes in order to vacuum system piping installation and easy connection, the outlet can be taken out from the horizontal direction, that is, the exhaust direction is perpendicular to each other. At this point, the exhaust port can open from both left and right directions, except the exhaust pipe connected to one end, the other end is blocked or access bypass valve. The pump structure of low center of gravity, high speed stability is good. Generally large, medium-sized pump more use of this structure. (3) The pump's two rotor shafts are mounted perpendicular to the horizontal. This structure is easy to control the gap assembly, rotor assembly convenient, small pump footprint. However, high pump center of gravity and gear disassembly inconvenience, lubricating mechanism is relatively complex. Only seen in foreign products. 2, pump drive Roots vacuum pump rotor is achieved through a pair of high-precision gear to achieve its relative synchronization. The drive shaft is connected to the motor via a coupling. In the transmission structure layout are the following two: One is the motor and gear on the same side of the rotor as shown. Driven rotor directly by the motor end gear to drive past, so that active rotor shaft torsion deformation is small, the gap between the two rotors will not change due to torsion and deformation of the drive shaft, so the gap between the rotor in operation The process of uniform. The biggest drawback of this transmission is: a. There are three bearings on the drive shaft, increasing the pump processing and assembly difficulties, disassembly and adjustment of the gear is also inconvenient; b. The overall structure is uneven, the pump center of gravity bias motor and gear Side of the box. The other is the motor and gear are mounted on both sides of the rotor. This form of the overall structure of the pump symmetry, but the drive shaft torsion deformation larger. In order to ensure uniform rotor clearance during operation, it is required that the shaft should have sufficient rigidity, and the coupling between the shaft and the rotor should be fastened (currently there is a structure in which the rotor and the shaft are welded or cast into one body). This structure disassembly are very convenient, it is widely used.