# Working Principle of Twin‑Screw Pump The twin‑screw pump is a rotary positive displacement pump. Its working principle is based on the volume change and axial delivery of closed chambers formed by the meshing of two screws. The core is that two intermeshing screws rotate to complete the suction, transfer and discharge of the medium. The specific working process can be divided into three stages: ## Suction Stage The two screws are driven by a motor and rotate synchronously in a predetermined direction (usually counter‑rotating). As the meshing teeth disengage gradually at the suction end of the pump, a partial vacuum is formed in the meshing space. Driven by external atmospheric pressure, the medium is drawn into the suction chamber of the pump. ## Transfer Stage As the screws continue to rotate, the sucked medium is trapped in multiple closed chambers formed between the screw grooves and the pump liner. These closed chambers do not leak due to the extremely small meshing clearance, and move smoothly and axially from the suction end to the discharge end as the screws rotate. During this process, the chamber volume remains unchanged, so the medium is not compressed and the delivery flow is stable. ## Discharge Stage When the closed chambers reach the discharge end of the pump, the meshing teeth re‑engage, the chamber volume is gradually compressed, and the medium is forced out of the pump body, completing one delivery cycle. ## Supplementary Key Features The two screws of a twin‑screw pump are the **drive screw** and the **driven screw**. The drive screw is directly driven by the motor, and the driven screw rotates synchronously through meshing with the drive screw, without the need for an additional gear transmission. The delivery process is smooth and **pulse‑free**, with low shear force on the medium. It is suitable for conveying high‑viscosity media (such as crude oil, lubricating oil, syrup), media containing micro‑particles, and shear‑sensitive fluids.
