Slide valve seal mechanical pump (referred to as the spool valve pump) with the same vortex pump, but also a varactor gas transmission pump. Its scope and conditions of use and rotary vane pump is basically the same. Because of its structural features, spool valve pumps are much larger than rotary vane pumps and are therefore often used in large vacuum equipment. Slide valve pump has a single-stage and two-stage two types. Single-stage pump pressure on the small pump ≤ 0.6Pa, on the large pump ≤ 1.3Pa (both off the town), two-stage pump ultimate pressure ≤ 0.06Pa (off gas town). Pumping speed greater than 150L / s spool valve to use more single-stage type. Due to the greater eccentricity of the spool pump's rotating mass, a large vibration can occur during operation if the slide is well balanced in mass. However, the motion trajectory of the pump rotating center of mass is a complicated closed curve, so it is very difficult to achieve a complete balance of the inertia force of the spool pump. To do a good balance of slide valve quality, reducing pump vibration has been an important issue to be solved by the slide valve pump.