What is Gearing: Definition and 27 Discussions

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. L

    Gears create more torque? Prove it

    Hi guys, I was sizing up a servo motor the other day and started thinking. While we all know gear ratios will effectively "convert" speed into torque. I couldn't help wondering about the initial starting conditions.. The problem below... Lets say I have a motor with a max load of 1Kg...
  2. D

    Question about the efficiency of a generator

    Using a certain kinetic energy, does a generator produce the same amount of electric energy even if I change the rpm by gearing? Also, does a generator produce energy in proportion to the number of rotation? I mean, does a generator create the same amount of energy between when it's rotated 10...
  3. S

    Gearing Backlash Arcsine to Arc minutes

    Working on a project at work for backlash in a gearbox. I need to know the amount of backlash in arc minutes that this particular ratio has. Wondering if my approach is on the right path. So can calculate the loose tolerance by the amount of end play in the input shaft and output shaft, add...
  4. SquidPhysics

    Microstepping, Gearing, and Torque

    So for my current project, I need to hold a crystal on a platform that needs to turn on the scale of microradians. I'm accomplishing this with a 1.8 degree/full step stepper motor that I'll be microstepping by 1/256 full step. To get to microradians, I'll need an additional division of steps...
  5. person123

    Magnetic Gears For Power Transmission

    This thread is an attempt to better understand the pseudo direct drive, or PDD, gear. What I do know is it's made up of a set of magnets which can serve the function of a reducer- a basic diagram of it as well as a video can be seen below. In this mechanism, the inner rotor is the input while...
  6. Eddie714

    I in designing a single speed reduction gearbox

    Hello, i am a junior mechanical engineering student and i was given the task of designing (on paper) a gearbox. I chose to design a worm gear single speed reduction gearbox. I know the basics of what composes it which are the worm, worm gear, input and output shaft bearings and the housing the...
  7. drwly

    Gearing & Torque: Can My Tricycle Motor Get the Job Done?

    I have put together a tricycle, but it only allows for a 4in sprocket on the axel. I have added a motor to the tricycle and do not get enough torque. The motor came with a 6in sprocket, which will not fit on the axil. My idea is to set it up so the chain goes from the motor 1in to the 6in to...
  8. T

    What Determines the Maximum Number of Gears on a Motorized Bike?

    So I have this motorized bike I made and I'm thinking about adding gears on to it over the summer. Anyways, it got me thinking and I'm confusing myself. So say you have an engine with a two speed transmission on it. For take off, you're in the smallest (or, biggest in size actually) gear so you...
  9. thorq

    Parallel string walking between two threaded cylinders?

    Hello, I have a problem that seems to have beaten me. I want to make a cable-driven reduction system between a threaded rod (pinion) and a larger threaded cylinder. Because of string walking, the string between the two has to stay at all times straight, parallel to the ground so that...
  10. K

    Gearing Down A High Speed Input (>10K RPM)

    Hello All, I am trying to find a combination of gearing technologies to satisfy the below design challenge. I don't see a commercially available solution; I am hoping you might be able to help me understand what physical effects make this design problem hard, and propose solutions worth looking...
  11. A

    Designing a Gearing System for an Analog Clock: Need Help!

    This task seems to me like it should be rather menial but I can't seem to wrap my head around it. I've already designed a circuit to run an analog clock with components I have already got sitting around my work bench. When it comes to designing the gearing though, I am struggling. My basic...
  12. A

    Zero backlash worm gearing for pan and tilt

    I am designing a Pan and tilt drive for with stepper motor as prime mover. We need a zero backlash worm drive to transmit 70 Nm. motor torque is 1 Nm. What are the options.. position accuracy is 0.1 deg. thanks
  13. C

    Epicyclic gearing: 3 free axes

    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)...
  14. D

    Tower Clock Gearing and Motor Speed

    Hello all, first post on here. My fathers friend recently died of cancer and he was the person we used to turn to for this question, I've been racking my brain and searching the net for info, found this link (http://www.schsm.org/html/gear_ratio_calculations.html) and have got the ratio down...
  15. L

    How does bicycle gearing affect mechanical advantage?

    Hey guys, I read through the other two bicycle gearing threads and to be quite frank I'm not sure if my question was answered. So to put it in it's most basic element, let's assume there's only one change, the gearing. Same bike, same crank length, pedal input, wheelsize, chain length. And...
  16. B

    Gear Geometry & Applied Theory: Intro Maths Needed?

    Folks, I have a book Gear Geometry and Applied Theory by Litvin. It looks pretty hairy and the diagrams/schematics of the kinematic relations etc are difficult to understand. What branch of mathematics does this fall under, diferential geometry and topology? I think I may need to get...
  17. Y

    RE: vehicle weight, HP, and gearing comparison between vehicles

    Hello all. I am now enrolled at VRI at WWU! I am working on a sort of independent study project. I am making a V12 out of a pair of motorcycle engines to go into a VW based kit car. I have run the IHP formula and come out with 250hp, and 220 lb/ft of torque. The car weighs 1800 pounds...
  18. L

    Studying Gearing Up For Calculus 2: Need Advice!

    Hi, you guys. I am going to take Calculus 2 next semester... And I would not say I am a math genius or anything... :/ So do you know of anything helpful to understand Calculus 2 very well? I want to study some over the break to have a head-start. Thank you! :)
  19. 0

    Firt time postjust a quick question about magnetic gearing

    just a quick question . I'm thinking about building myself a vertical axis wind turbine and using the turbine to power a few lights around the house . my question is about using a magnetic gearing system . and will it work (produce more power than just using the base of the turbine with...
  20. K

    Calculate gearing changes based on windspeed?

    Hi All, I'm looking for a set of equations to allow me to calculate gearing changes based on a known tail/head wind speed, anyone got any starting points? 4 speed transmission and a fixed engine output. Cheers,
  21. S

    Drive Motor Requirements for Gearing/Torque Transfer

    I have a question regarding gearing and torque transfer. If I had a receiving stator that requires 3600rpm/26 lb ft torque, and needed to get a drive motor to turn it at those parameters using an 18:1 ratio, what would the drive motor need to be capable of, performance-wise? This will be a real...
  22. K

    Is a Toroidal Engine a More Powerful Alternative to Reciprocating Engines?

    Does anyone know of any gearing assemply like what I am looking for - - - sort of the opposite of a Geneva Mechanism. It would have a drive that, during the first four 90 degree increments of the input, the output also increments in 90 degree intervals. In the fifth and sixth 90 degree...
  23. L

    Thanksgiving Dinner Debate About GoPed Gearing

    Ok my friend and I are having a disagreement about gearing on a GoPed. I am stating that if you change the tire size of a California GoPed the speed of the GoPed will not change. This is all theory so am not taking into account friction, mass or the like. For those of you who do not how a...
  24. A

    Gearing Mechanics: Torque/HP & Gear Ratio Explained

    anybody know the mechanics of gearing, like on a bicycle, motorcycle, or car? what is the relationship between gear ratio and torque/hp? i mean we all know that starting the car in higher gears isn't as easy as first, same goes for a bicycle...anybody know the details?
  25. zoobyshoe

    Gearing Up For Projects That Fizzle

    Ever got everything assembled for a project only to have you interest fizzle before you actually got started on it? Im my case there seems, sometimes, to only be enough interest to get me through the gathering of materials stage, and then my interest is "used up". One biography of Edison...
  26. W

    Can you create a limited slip differential using only gearing?

    I'm not educated in mechanics, and there is one nagging idea I can't get answered that's related to limited slip differentials. I understand all types of diffs, and while learning them and requirements for best traction came to one idea about possibly good LSD, but, I can't imagine how it...
  27. J

    X-Prize Competitor gearing up for test

    http://story.news.yahoo.com/news?tmpl=story2&cid=96&ncid=96&e=6&u=/space/20030403/sc_space/x_prize_competitor_unveils_manned_space_capsule Hope that long link worked, if not you can read about it at http://www.space.com/ Basically a group is going to be testing a small version of their...