Does a planetary gear system affect the torque felt by an electric motor?

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Discussion Overview

The discussion centers on the effects of a planetary gear system on the torque experienced by an electric DC motor when connected to a load via a drum. Participants explore the relationship between the motor's torque, the gear ratio, and the load torque applied to the drum.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that the motor will feel the torque T from the load, indicating that the planetary gears increase transmitted torque, resulting in the motor "feeling" less torque due to decreased rotation speed.
  • Another participant questions the type of engine being referred to, seeking clarification on the motor's characteristics.
  • A participant clarifies that the motor is a simple DC motor without a built-in gearbox, which may influence the torque dynamics.
  • One participant believes that the torque felt by the motor will be the load torque divided by the drum's diameter and then divided by the gear ratio, suggesting that the motor will perceive this load as work to do, similar to overcoming drag or incline in a vehicle.
  • Another participant argues that the motor and load will not experience the same torque, emphasizing that the torque difference is determined by the gear ratio and should be considered when analyzing moments in a free body diagram.

Areas of Agreement / Disagreement

Participants express differing views on how the torque is transmitted through the planetary gear system and how it affects the motor. There is no consensus on the exact relationship between the motor torque and the load torque.

Contextual Notes

Participants have not fully resolved the implications of the gear ratio on the torque experienced by the motor and the load, and assumptions about the system's configuration may influence the discussion.

ENgez
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lets say i have an electric dc motor and i connected its shaft to a planetary gear system. this planetary gear systems last stage's ring (outer rim) spins a drum. this drum feels an outer torque T as a consequence of loads. my question is motor will feel torque T, because i read that the planetary gears increase transmitted torque (the engine will "feel" less torque) as result of decreasing rotation speed
 
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What engine are you referring to?
 
a simple dc engine that supplies torque using a shaft .it has no built in gearbox.
 
I thi
 
I think your motor will indeed "Feel" this torque T from load. It will be divide by the diameter of the drum, then divided by the gear ratio to get the final torque on the motor.


I do believe that if the motor and gearing are appropriate this drum load torque will be "seen" by the motor as work to do, nothing special. For example, if this were a car, it would be similar to drag or going up a hill.


drum+torque.jpg
 
Motor and load will not see the same torque. They will be different by a factor equal to the gear ratio. If you are trying to balance the sum of the moments in a free body diagram, then don't forget that the difference on torque is taken out by the gear box case.
 

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