Planet Gear System: Sun Gear Input, Same Torque in Ring & Carrier?

In summary, a planetary gear system consists of a sun gear, planet gear, ring gear, and carrier. The sun gear delivers the input torque and there are two torques that can result: one from the ring gear and one from the carrier. However, these torques are different due to the number of teeth. It is not possible for a standard planetary gear system to have the carrier and ring deliver the same torque, as different gear ratios imply different torques. However, an unusual planetary differential can provide equal torque to two axles by driving the carrier with two suns.
  • #1
Trying2Learn
373
57
TL;DR Summary
Output torque
Hello all,

In a planetary gear system, there is:

  1. sun gear
  2. planet gear
  3. Ring gear
  4. Carrier
Suppose the SUN gear delivers the input torque to the system.

(I do not care about the planet gears in this system.=

There are two torques that can result.
  1. The ring can deliver a torque and
  2. the carrier can deliver a torque.

However, the torques are different due to the number of teeth.

Has anyone ever heard of a design system in which the carrier and ring deliver the SAME torque?
 
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  • #2
Seems like an easy thing to do. Connect each to a constant-torque load and let 'er rip.

The constant-torque load could be a friction brake, for instance. Speeds, of course, would differ.
 
  • #3
Trying2Learn said:
Has anyone ever heard of a design system in which the carrier and ring deliver the SAME torque?
Power = torque * RPM, so different gear ratios imply different torques.
When you lock the carrier, the ring is effectively driven backwards by the sun.
When you lock the ring, the carrier moves forwards at half that speed.
So I don't think it is possible for a standard planar planetary gear to offer equal torque.

The unusual planetary differential does provide equal torque to two axles, but in that case the carrier is driven, without a ring, but with two suns.
https://en.wikipedia.org/wiki/Differential_(mechanical_device)https://en.wikipedia.org/wiki/Differential_(mechanical_device)#Spur-gear_differential
 

1. What is a planet gear system?

A planet gear system is a type of gear system that consists of a central sun gear, a ring gear, and multiple planet gears that rotate around the sun gear and mesh with the ring gear. This system is commonly used in automotive transmissions and other machinery to transfer torque and power.

2. How does a sun gear input affect the system?

A sun gear input is when the power and torque is applied to the central sun gear. This causes the planet gears to rotate around the sun gear, which in turn rotates the ring gear. The direction of rotation of the ring gear will depend on the number of teeth on the sun gear and the planet gears.

3. Why is it important for the ring and carrier to have the same torque in a planet gear system?

In a planet gear system, the torque is distributed among the planet gears, ring gear, and carrier. If the torque is not equal in the ring and carrier, it can cause uneven wear and tear on the gears and lead to premature failure of the system. Therefore, it is important for the torque to be balanced to ensure the longevity and efficiency of the system.

4. What factors affect the torque in a planet gear system?

The torque in a planet gear system is affected by several factors, including the number of teeth on the sun gear and planet gears, the gear ratio, the size and shape of the gears, and the material and quality of the gears. Additionally, the input speed and power also play a role in determining the torque in the system.

5. How does the planet gear system achieve speed reduction?

The planet gear system can achieve speed reduction by using a gear ratio between the sun gear and the ring gear. The number of teeth on the sun gear is typically smaller than the number of teeth on the ring gear, which results in a lower output speed compared to the input speed. This allows for the system to transfer power and torque at a reduced speed, which is useful in various applications such as automobiles and industrial machinery.

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