Progressive Cavity Pump

Overview

A progressive cavity pump moves fluid with a single steel helix turning inside a rubber double-helix, a geometry credited to René Moineau. The PCP Rotor (single helix) and the PCP Stator together form a chain of sealed cavities; because the rotor has one fewer lead than the stator, those cavities do not rotate but instead march steadily from suction to discharge as the rotor turns. Each cavity carries the same volume, so the pump delivers a smooth, nearly pulseless flow that is almost independent of pressure, ideal for thick, shear-sensitive, or solids-laden fluids that defeat centrifugal pumps.

Fluid enters through the Suction Housing. Torque reaches the rotor through the Connecting Rod, whose universal joints let the rotor follow its eccentric orbit while the Drive Shaft Assembly keeps the shaft sealed and supported. A Drive Motor and Reduction Gearbox set the low speed the pump runs at, and the Bed Plate holds everything in alignment.

How it works

The single-lead PCP Rotor (single helix) does not spin on a fixed axis; it rolls and orbits inside the two-lead Stator Elastomer Lining, its centerline tracing a small circle. That orbiting motion is why a rigid shaft cannot drive it directly. Instead the Connecting Rod carries torque through two Universal Joint joints, one at the drive end, one at the rotor, each protected by a grease-filled Joint Boot. The rod lets the rotor wander eccentrically while the drive shaft stays on a fixed centerline.

The PCP Stator is the heart of the pump and its main wear part. Its bonded elastomer is sized for a slight interference fit against the rotor, so each cavity is positively sealed; this is what lets the pump build high pressure and self-prime. The elastomer is matched to the fluid, nitrile for oils, EPDM for chemicals, FKM for aggressive media, and it sets the temperature and abrasion limits.

Output rises directly with rotor speed, so flow is set by the Reduction Gearbox ratio and the motor speed rather than by throttling. Running the pump dry burns the stator quickly because the fluid is its only lubricant, so these pumps are protected against dry running and are valued for metering and for transferring sludge, paste, and viscous product gently.