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When I originally posted this question 2021-04-08, I was inspired by pulley physics, especially after viewing these videos at this link and this link and this link. It is not necessary to go to these links. Just to bear in mind the concept that inspired my question which is that less kinetic force on one end is needed through a series of simple machinery to lift more weight at the other end. I began to wonder if there is an equivalent method in physics to do something similarly in axial gear machinery so that the force applied on one end of the axle is amplified to move more weight, cause more torque, and increase the rotational speed on the other end of the axle.

enter image description here

I began to conceptualize something along the lines of the above planetary gear set (epicyclic gear train), where input force/energy on one end of the axial is amplified through a series of transmission gears so that the output side has more speed and torque. The machine I envision is a simple compact machine that converts in line axial rotational motion into mechanical advantage so that the same work can be done with less applied force.

The question then becomes this: How can rotational kinetic energy be amplified, and does anything already exist that accomplishes this?

Conceptually, what I am after is the mechanical analog of what the electrical transformer/inverter does when input electrical energy goes into the system. However, in this present question, it is not electrical energy, but kinetic energy that is being transformed/inverted/amplified. So a related physics question would be: how can kinetic energy be amplified in rotational machinery and applied to the simple compact machine described in this present post?

These are my questions which I will be most grateful to know. Any suggestions or insights would be most helpful.

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  • $\begingroup$ Please provide detailed information on your question. I won't expect people to watch the video or the linked material to frame out the problem for me. You need to show your own works. $\endgroup$
    – r13
    Apr 9 at 3:18
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    $\begingroup$ Not sure what the question is, but is this what you're looking for? en.wikipedia.org/wiki/Gear_train $\endgroup$ Apr 9 at 9:31
  • $\begingroup$ you cannot increase rotational speed and torque at the same time. Regarding the concept of kinetic energy, it is not applicable in this case (at least not in the way I understand you are using it). $\endgroup$
    – NMech
    May 9 at 6:30
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A simple machine is what you're referring to. A simple machine turns motion into mechanical advantage. Examples include:

  • lever
  • inclined plane
  • pulleys
  • wheel & axle
  • gears
  • inclined plane/wedge/screw

These machines convert extra motion or rotation into mechanical advantage so that the same work can be done with less applied force.

As for this:

How can rotational kinetic energy be amplified, and does anything already exist that accomplishes this?

It's generally called a motor.

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No.

You cannot increase both torque and speed without adding more energy to a system. In a gear train/belt & pulley combo, you have one member rotating slower but with higher torque and the other faster but with lower torque. You would need an outside power source to further increase the speed or torque beyond what you input, per the conservation of energy.

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Planetary gear? Both shafts will rotate at a different speed / transmit a different torque, depending on what you're after.

Electric drills often use these gearboxes if they have multiple speeds.

enter image description here

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    $\begingroup$ Harmonic drives is another one. $\endgroup$
    – DKNguyen
    Apr 13 at 2:44

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