The use of a Drag Spring at the bottom of the test string will prevent the lower half of the Inflate Pump from rotating while pumping. With the lower section locked, the upper half of the Inflate Pump rotates on roller bearings and roller thrust bearings to carry the drill string weight below. This action engages the drive and camshaft assembly which in turn activates four pistons, arranged radially in connected pairs.
The pumping action of the pistons pulls drilling fluid into the bottom of the pump through
a Suction Screen which filters out cuttings that could impact pump and packer operational performance. Suction valves have been designed to sense discharge pressure and will stop the pumping action when a desired preset pressure is achieved (usually 1,500 psi or 10,340 kPa).