Epicyclic Definition and 13 Threads

An epicyclic gear train (also known as a planetary gearset) consists of two gears mounted so that the center of one gear revolves around the center of the other. A carrier connects the centers of the two gears and rotates to carry one gear, called the planet gear or planet pinion, around the other, called the sun gear or sun wheel. The planet and sun gears mesh so that their pitch circles roll without slip. A point on the pitch circle of the planet gear traces an epicycloid curve. In this simplified case, the sun gear is fixed and the planetary gear(s) roll around the sun gear.
An epicyclic gear train can be assembled so the planet gear rolls on the inside of the pitch circle of a fixed, outer gear ring, or ring gear, sometimes called an annular gear. In this case, the curve traced by a point on the pitch circle of the planet is a hypocycloid.
The combination of epicycle gear trains with a planet engaging both a sun gear and a ring gear is called a planetary gear train. In this case, the ring gear is usually fixed and the sun gear is driven.

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  1. M

    Engineering Two Stage Epicyclic Gear-box - Finding the Gear ratio

    Hi, Just have a question about the method in attempting this two-stage epicyclic gear-box. We are given the following information about the number of teeth: S1 = 48, P1 = 28, S2 = 96, and P2 = 48 My attempt: 1. Work out the number of teeth for the two ring/annulus gears From geometry, we can...
  2. X

    Planetary gearbox speed calculation - Simultaneous equations

    I'm looking to calculate the ratio of a planetary gear train. With the ultimate goal of producing a spreadsheet/calculator to show the state of the gearbox (i.e. all shaft speeds) based on applied constraints. A gear set consists of Ring Gear, Planet Gear, Sun Gear. The sick diagram is the...
  3. S

    Magic of Mechanics - Epicyclic (planetary) gears

    All About Epicyclic gearing This Video illustrates : - How does Epicyclic gear Work - some Application of Epicyclic gear - How to make Epicyclic gear calculation
  4. A

    Mathematical relation between dipole moment and frequency?

    how can we relate innermost stable circular orbits, keplerian, epicyclic, frame dragging precession frequency with dipole moment.
  5. C

    Can Epicyclic Gearing Operate with No Fixed Axis?

    Homework Statement The teacher said it is possible to use an epicyclic gearing with no axis fixed but nobody use the gearing like that. I watched this video: at time 42s it's possible to watch it. I have 2 questions: 1) Is it possible to used the epicycloidal train with no axis fixed ? 2)...
  6. W

    Epicyclic motion and precession

    Imagine I am standing but not moving forward/backward, but I am rotating my body about my own axis. Now imagine if I moved in a circular path as I was spinning on my own axis. Is this considered to be precessing (assuming the axis of rotations are always in the z direction)? My friend...
  7. L

    Calculating Gear Ratio for Epicyclic Gear Train

    Homework Statement Here the gear B is fixed and C and D are on the same drive. If C has 100 teeth, B has 50, D has 50 and E has 200. Calculate the ratio of the gearbox. Homework Equations The Attempt at a Solution My attempt is uploaded as an attachment as putting tables in...
  8. marellasunny

    Epicyclic gear:modules for the sun,planet and ring gear

    Is the module(M) of the sun,planet and ring gear in a 'planetary gear set' equal to each other always? Is it possible for M to be different for each of the gears in the set?[-Applications of this?] $$PCD_{Ring}=PCD_{Sun}+2*PCD_{Planet}\Rightarrow N_{Ring}=N_{Sun}+2*N_{Planet}$$ is valid only...
  9. M

    Is Epicyclic an Accurate Term for the Moon's Orbit Around the Sun?

    Hi, A quick clarification question. Is epicyclic a correct description for our moons path around the sun. I can only find references to epicycles in a historical context. Thanks.
  10. S

    Epicyclic gear train- finding teeth

    Homework Statement A gear ratio is req from A/D of 1:100 and that it will be necessary to redesign D so that it has 100 teeth. Determine: a)number of teeth on c b)number of teeth on planet gears. This followed on from another question. An epicyclic gear c is the annulus and is fixed. The...
  11. D

    How Do You Solve a Complex Epicyclic Gearbox Assignment?

    Hi all, I'm Chris, a first time poster! Currently stuck on an assignment question for my mechanical engineering course. The question is shown in the picture below. The capital T refers to 'teeth', as in 20T is 20 teeth on that particular gear. Ignore the little arrows with P and S - that is...
  12. G

    What is the output speed at 100 rpm arm rotation in an epicyclic gear box?

    Hi, Cant understand this at all, even modeled the set up with lego but still can't fathom it! I can't see how the arm can rotate with locking something. Cheers
  13. B

    Epicyclic Gear Train Homework: Why Does $\omega_3=\omega_6$?

    Homework Statement http://img8.imageshack.us/img8/2393/geartain.jpg The Attempt at a Solution I got the right answer, by assuming that \omega_3=\omega_6 , but i don't know why this has to be so. Here's my working: \frac{\omega_2-\omega_3}{\omega_4-\omega_3}=-\frac{N_4}{N_2}...
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