The calculated and experimental axial forces on the screws of the EVNOP 5-16-1200 and EVNOP 5-30-1200 high-pressure single-screw single-flow pumps are compared. The pumps are used in oil-extraction systems. On the basis of test results for single-flow pumps with a bearing, the actual axial force may be measured. This permits correction of the formula for the axial force on the screw in production conditions.