الفهرس 
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Abstract
This work deals with the application of the theory of externally pre¬irized lubrication to the different types of power screw-nut systems,
fln this application, the sliding surfaces of the screw and nut threads, are seperated by a pressurized fluid film, fed from an external supply :ough a continuos helical recess cut in the thread flank of the nut. is eliminating two of the most defective obstacles countering the idl performance of dry power screws, which are, the ”Bapek-lash” and the creasing wear during operation. Further improvements in the perform-
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a-nce characteristics of power screws, are also resulted from this dev¬,--lopment, such as high efficiency of power transmission.
These valuable advantages make the externally pressurized power screw admirably suitable for applications where accurate positioning and min¬imum frictional resistance, are essential objectives.
The wide scope of application of this type of machine elements, and the great lack of published informations, recommended this study.
Due to the complexity of the helical flank surface, the few previous trials, concerning this problem, were approached either by approximate solution, or by experimental work, and specifically applied to the known traditional types of power screws. Therefore, it was an objective o-Jr-, this work to reveal the exact perfoi-manse characteristics of power sc¬rews, when externally pressurized, in order to present an adequate uil.-- derstanding about their behaviour under such new operating conditions