Dry screw vacuum pumps operate with two screw rotors rotating in opposite directions. This traps the medium to be pumped between the cylinder and the screw chambers and Transports it to be the gas discharge. Vacuum is formed by the principal of suction, Compression and discharging through passing regular intervals of two small pitches. Hybrid Combined Variable Pitch is a screw type to remedy the disadvantage of Single pitch and adjustable-pitch compare to conventional single pitch.