How Power Screws Work - Explained with Illustrations

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SUMMARY

The discussion centers on the mechanics of power screws, particularly in relation to their function in linear actuators and ship propellers. A power screw operates on the principle of a wedge, where an inclined plane interacts with water to generate thrust. The conversation highlights the importance of understanding the forces at play, including thrust loads and potential stall angles, which affect the efficiency of power screws in various applications. Additionally, the mention of Machine Design notes suggests a wealth of technical information available for deeper exploration.

PREREQUISITES
  • Understanding of basic mechanical principles, including force and motion.
  • Familiarity with linear actuators and their applications.
  • Knowledge of the mechanics of screws and wedges.
  • Basic concepts of fluid dynamics, particularly in relation to thrust generation.
NEXT STEPS
  • Research the mechanics of linear actuators and their design considerations.
  • Study the principles of fluid dynamics as they apply to propeller and screw design.
  • Explore the concept of stall angles in power screws and their impact on performance.
  • Review Machine Design resources focusing on power screws and their applications in engineering.
USEFUL FOR

Mechanical engineers, students of machine design, and professionals involved in the design and application of linear actuators and propulsion systems will benefit from this discussion.

stan
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hi

does anyone knows how a power screw works, illustrations would be helpful..
thanks


ss
 
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It's the same principle as a regular screw...a wedge. What are you looking for?
 
If you're talking about say the propeller of a ship, then imagine an inclined plane sitting in a body of water. Then, just move it straight up through the water. The water will exert a force on the plane perpendicular to the plane. There will be two components of that force, one being in the x direction, a thurst load wanting to push the plane horizontally through the water.

Just note that this is very simplified, I'm sure there are other effects, and there is probably a "stall" angle where for a given rpm, and angle, the screw won't want to produce any axial force (although I would think you could go with a higher angle on a screw than just a straight propeller). Anyways...
 
I think Stan is referring to a linear actuator type of power screw.
 
Last edited:
OOOOoooo, power SCREW, haha. I have like a week and halfs worth of Machine Design notes on Power Screws somewhere at home. I'll look later for them
 

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