First find the gear train value that is the ring speed with respect to the sun speed, call it e. The gear sets are referred to as the front and rear gear set. Planet gears rotate around axes that revolve around a sun gear, which spins in place. You could rearrange things again, and this time hold the sun gear stationary, take the output from the planet carrier and hook the input up to the ring gear. Planet gears rotate around axes that revolve around a sun gear.
Calculation of a planetary gear train this tutorial shows the usage of mesys shaft calculation with shaft systems. A planetary gear train is very much like our own solar system, and thats how it gets its name. The epicyclic gear train family in general has a central sun gear which meshes with and is surrounded by planet gears. One of the popular arrangements is called the simpson gear train. Following are the different types of gear trains, depending upon the arrangement of wheels. Planetary gear trains are common in industrial, automotive, and aerospace systems. The outermost gear, the ring gear, meshes with each of the planet gears. As the carrier rotates, planets rotate on planet gear shafts while orbiting the sun. Planetary gears are common in transmission systems, where they provide high gear ratios in compact geometries. Most of the automatic transmissions use this kind of gear train. In many cases, one of these inputs will be zero velocity, i. If the carrier is acting as the output in the planetary gear system, being rotated by the sun gear while the ring gear stays still, divide the number of teeth on the planetary gears the driven gear by the number of teeth on the sun gear the driving gear. The two sun gears are centrally located and separated longitudinally along a common rotation axis. A common use of a planetary gear set is in an automatic transmission where two 2 planetary gear sets are combined.
When the ring d is stationary, the spider a, which carries three planet wheels c of equal size, is to make one revolution in the same sense as the sun wheel b for every five. The center distance of each gear pair of one concept sun planet gear or ring planet gear must be equal using a small number of teeth while also complying with further assembly rules will create a gear set with a number of teeth that meet the desired transmission gear ratio, with only a certain deviation. The most basic form of planetary gearing involves three sets of gears with different degrees of freedom. Selfcentering characteristics of floating sun gear in a startype planetary gear train. Each of these three components can be the input, the output or can be held stationary. Planetary gear trains are one of the main subdivisions of the simple epicyclic gear train family. This gear has an inner hub c which is fixed to b and in mesh with the fixed ring gear r. This arrangement uses a common sun gear shared by both planetary gear sets. The angular velocity of gear 2 relative to the arm in revmin is the velocity of gear 5 relative to the arm is 47 sun gear 2 arm 3. The epicyclic gear train consists of the sun gear a which is in mesh with the planet gear b. Sun gear is located at the center that transmits torque to planet gears orbiting around the sun gear.
Patel institute of engineering, vitthal udyognagar abstract. A planetary train composed of sun gear 2, an arm or carrier 3, and planet gears 4 and 5. The inputand output shaftsare coaxial andthe inputand output 1 torques are assumedto be coaxialwith these shafts. A planetary gear train planetary trains always include a sun gear, a planet carrier or arm, and one or more planet gears. Then sun gear a will rotate times and carrier d times, leading to the reduction ratio of. Ideal planetary gear with sun, ring, and carrier simulink. Planetary epicyclic gear ratios equations and calculators.
A planetary gear train is a little more complex than other types of gear trains. Gear 1 is called a sun gear, gear 2 is a planet, link h is an arm, or planet carrier. In the first three types of gear trains, the axes of the shafts over which the gears are mounted are fixed relative to each other. Introduction to gear trainsintroduction to gear trains. The article will discuss the sun and planet gear arrangement of a typical epicyclic gear train and its applications. Other articles where sun and planet gear is discussed. The sun and planet gear is a method of converting reciprocating motion to rotary motion and was used in the first rotative beam engines it was invented by the scottish engineer william murdoch, an employee of boulton and watt, but was patented by james watt in october 1781. To avoid damage to the motor housing, use the special repair tools designed for the disassembly and assembly of this motor. The planetary gear block implements an ideal planetary gear coupling consisting of a rigidly coupled sun, ring, and carrier gears.
The selected materials had to meet strength requirements while being cost effective. Pdf investigation of materials for shaft and sun gear of. Figure 5 shows the ravigneaux gear train, a combination of one simple and one compound planetary gear set, which has dual sun and planet gear sets with a single ring and common carrier holding two planetary gear sets. Design of machinery an introduction to the synthesis and. This is because the planet carrier circled the sun gear once in the same direction as it was spinning, subtracting one revolution from the sun gear. Typically, the arm and the sun gear will each be driven in some direction at some velocity. A reliabilitymodel is presentedfor planetarygear trains inwhich the ring gear isfixed, the sun gear isthe input,and the planet arm isthe output.
An incredibly odd hydraulic system that controls the clutches and bands. Epicyclic gearing systems also incorporate the use of an outer ring gear or annulus, which. Nov 08, 2018 in this video solve numerical problem related to epicyclic and sun and planet gear train. A large gear pump to move transmission fluid around. Determine the following if the engine drives the input planet carrier at 4000 revmin. This project dealt with the selection of materials for a harmonic planetary gear system. Sun gear p planet gear r ring gear a a r m ex ampl e.
In this video solve numerical problem related to epicyclic and sun and planet gear train. Planetary kinematics note that point 1 on the planet gear is stationary zero velocity due to noslip assumption note that point 2 on the planet gear has the same velocity as point 2 on the sun gear also due to noslip assumption, which is given by. Typically, the planet gears are mounted on a movable arm or carrier, which itself may rotate relative to the sun gear. Planetary gear with two sun gears and two planet gear sets. Pdf selfcentering characteristics of floating sun gear in.
The angular speed of the planet carrier can be found since we. Pinion gear 8 pitch diameter 4 planet carrier 11 planetary gear set 11 power transfer unit 16 rearwheel drive rwd ring gear 11 spiral bevel gear 6 spur gear 5 sun gear 11 torque 2 torque converter 11 transaxle transfer case 16 transmission 8 universal joint ujoint 14 worm gear 6 key terms after studying this chapter, the reader should. In a planetary train at least one of the gears must revolve around another gear in the gear train. Use these instructions along with the tool parts page or manual. The sun and planet gear converted the vertical motion of a beam, driven by a steam engine, into circular motion using a planet, a cogwheel fixed at the end of the connecting rod connected to the beam of the engine.
The sun and planetary gear arrangement, sometimes also called as epicyclic gear train, is a gear train, where typically few smaller gears rotate and revolve by meshing around a bigger sun gear. Then consider the mechanism is used in the automatic transmission of a car. Pdf investigation of materials for shaft and sun gear of a. The ravigneaux gear block represents a planetary gear train with dual sun and planet gear sets. In the solar system the planets revolve around the sun. The block calculates the dynamic response to the sun, carrier, and ring input torques.
The input shaft was modelled as a cantilever beam carrying the weight of the. The input gear has 20 teeth and the output gear has 100 teeth. From our study of normal 2 gear interactions we know that the amount of traversal is determined by the number of teeth on each gear. Epicyclic gearing or planetary gearing is a gear system consisting of one or more outer, or planet, gears or pinions, revolving about a central sun gear or sun wheel. Sun gear planet gear outer ring planet carrier figure 3. Usually the sun gear has a metal shell cup shaped attached to it in order to allow the gear to be utilized. Article pdf available july 1997 with 346 reads how we measure reads.
In the toothed formation sun and planet gears are externally mesh and ring gear internally meshes. In this case, the planet gears have 12 teeth, the sun gear has 18 and the ring gear has 42 teeth. Working out planetary gear turns ratios working out the gear ratio of a planetary gear train can be. Ring, sun and arm are sequentially fixed in some order. How to derive and calculate epicyclic gear ratio equations in. Now, industrial applications demands high torque in compact a high. This block models a gear train with sun, planet, and ring gears.
This has become an epicyclic train with a sun gear and a planet gear orbiting around the sun, held in orbit by the arm. These gear arrangements give different speed ratio options. Lightweight design for planetary gear transmissions. Introduction planetary gear systems normally consist of a centrally pivoted sun gear, a ring gear, and several planet gears found between the sun gear and ring gear. Planetary gear system is an assembly of gears where one or more planet gears revolve around a gear placed at centre named sun gear and a ring gear encircles the. The sun gear is located at the center, and transmits torque to the planet gears that orbit around it. Murdock also experimented with compressed air and in 1803 constructed a steam gun. In this case, planet gear b will rotate only for transmitting the motive power as a nonvital gear. A twostage planetary gear stage is defined using the program. The smaller of these gears engages an inner planet gear set, which in turn engages an outer planet gear set.
The planet gear in figure 23 rotates about a fixed bevel gear at the center of which is the driven shaft. Planetary gear design a planetary gear system, also referred to as epicyclic gearing, consists of three elements a sun gear, one or more planet gears, and a ring gear. We know that for each turn of the planet tp the planet will travel around the sun npns times taking the carrier with it in the process where np planet gear teeth and ns sun gear teeth. A typical application is the automatic transmission system of car. Planetary gears, gear train, is 4460, torque density. Understanding to compute the speeds of gears in an epicyclic sun and planet gear train by tabular method. Their can be either three 3 or four 4 planet gears in the planet. Choosing which piece plays which role determines the gear ratio for the gearset.
Gear train with sun, planet, and ring gears matlab. From a kinematic point of view, what sets this mechanism apart is the kinematic constraint set between gear pairs. Planet gear for each planet gear, we can write nslr as follows. In a compound epicyclic gear train as shown pdfinancialcorp com in the figure, has gears. Next, suppose carrier d is fixed, the input axis is connected to sun gear a, and the output axis planet internal gear c. With the motion of the beam, this revolved around, and turned, the sun, a second rotating cog fixed to the drive shaft, thus generating rotary motion. A carrier connected to a drive shaft holds the planet gears. Please start with the tutorial for shaft calculation to see how to introduce geometry and supports for single shafts. All the components are modelled in catia to check the assembly and the. Since the sun gear the largest gear is fixed, the dof of the above mechanism is one. In a planetary gear train the sun gear is at the center. Given a planetary gear train, with ring, sun, planet, and arm, where teeth numbers are shown in the figure. The sun is the center gear, meshing with the planets, while the carrier houses the planet gear shaft.
The planet gears are held to a cage or carrier that fixes the planets in orbit relative to each other. A gear train is two or more gear working together by meshing their teeth and. Other uses for gears how gear ratios work howstuffworks. Planetary or epicyclic gear train gear train mechanical. Given a planetary gear train, with ring, sun, plan. That is to say, the number of teeth in the ring gear is equal to the number of teeth in the middle sun gear plus twice the number of teeth in the planet gears. Two forms of planetary gears of the bevel type are shown in figures 23 and 24. Example 2 a compound epicyclic gear train overdrive has sun, small planet and large planet gears with 21, 15 and 24 teeth respectively. About the size of a cantaloupe, this one part creates all of the different gear ratios that the transmission can produce. When there are three or more planets, as is the usual case, care must be made to make sure the teeth of both planets can engage.
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