Abstract: - Gears in the Epicyclic gear trains are one of the most critical components in the mechanical power transmission system in which failure of one gear will affect the whole transmission system, thus it is very necessary to determine the causes of failure in an attempt to reduce them.
The different modes of failure of gears and their possible remedies to avoid the failure are mentioned in J. Kannaiah [18] [20] as bending failure load failure , Pitting contact stresses , scoring and abrasive wear, in any case it is related to the loads acting on the gear and this research deals with the Optimization of the gear design leading to the reduction in the load failure of the gears.
Further, table. This study carried out in this research shows the optimization analysis of the epicyclic gear train in INDIA to reduce load failure. The analysis is restricted to the optimization of gear train through load analysis of the gears, pinions and annulus including the sun and plant gears, and finding out the optimal load conditions for the gear train to perform effectively without leading to load failure.
Epicyclic Gear Trains have been used in Industry for their many advantages which includes high torque capacity, comparatively smaller size, lower weight, improved efficiency and highly compact package, however there has not been a comprehensive study of its load bearing performance with respect to different parameters such as module, material, and power of the epicyclic gear trains [16] [17]. This research paper provides an attempt in filling that gap in aiming to get the epicyclic gear trains load performance on different parameters.
This process helps in finding the optimized design for the epicyclic gear trains in which it has the best performance without any failure and with minimum Loads acting on the gears. The main aim of this research investigation is to optimize the epicyclic gear train through load analysis, to prevent load failure from happening in the future.
Usually, an epicyclical gearing systems are employed to achieve high reduction ratio in a small and power dense package. It is examined that load sharing capability is not equal in the planetary gear train. These Gear Trains are extensively used for the transmission and are the most critical component in a mechanical power transmission system.
They play a very vital role in all the industrial areas, any failure in the gear train leads to a total system failure, thus identifying the causes and optimizing to get the best performance is very necessary. The advantages of epicyclic gear trains are higher torque capacity, lower weight, small size and improved efficiency of the planetary design. Thus the loads have to be minimum to reduce the stresses in the gear train. The epicyclic gear train model is taken from BHEL, and some of its parameters have been modified to optimize its performance.
The gear train consists of five external gears and 4 internal annulus gears, including sun and planet gears forming an epicyclic gear train. The present work on epicyclic gear trains carries out the design of all the gears, Shafts, keys and the loads are calculated for individual gears in the epicyclic gear train system.
The analysis is divided into three parts, in which the first www. As the condition was stated that for preventing Gear failure the Static Tooth Load Ws and the dynamic Tooth Load Wd should be greater than the Wear Tooth Load Ww [15] [19], This condition is analyzed for the entire gear train and optimized for to get the least loads on the gears. As these Gear trains are subjected to high loads during their operation they are subjected to high stresses in the process which may cause failure, thus calculating the loads for different modules and for different power levels will show us the best optimized design of the gear train.
This paper shows the optimization of gear trains with varying the modules and power of the entire gear train. Avinash [ 1 ] Load Sharing behavior in epicyclic gear trains P. Sunyoung [ 17 ] Failure analysis of a planetary gear train A. Yuksel [ 7 ] Dynamis tooth load of planetary gear sets M. Gupta [ 15 ] Contact stress analysis of spur gear A.
Hassan [14 ] Contact stress analysis of spur gear teeth pair II. The Gears, arms, keys and annulus are designed in Solidworks which is shown in Fig. This model of the epicyclic gear train failed due to the high loads acting on the gears. As we know that the gear is one of the most critical components of the power transmission system, failure in the gear will affect the whole transmission system and thus it is necessary to optimize the gear for low load operation and its effective delivery of power transmission.
The modules 1. Systems of Gear Teeth:-The following four systems of gear teeth are commonly used in practice. Gear Material:-The materials which are used for the gears depend upon the service factor and strength like wear or noise conditions etc, and they come in metallic and non-metallic form. For industrial purposes metallic gears are used, commercially can be obtained in steel, cast iron and bronze. The parameters for the gears are mentioned in Tables 2, 3 and 4. As the below calculations are performed, similarly the calculations are done for the rest of the eight gears for modules 3, 4, 5 and 6.
All the results are tabulated for Table. It is the load acting perpendicular to the radial tooth load Wr and normal tooth load Wn [16] [18] as shown in the fig. It depends upon the curvature of tooth profile, elasticity and surface fatigue limit of the gear material. It uses Buckingham equation [18] [16].
Similarly the loads for rest of the eight gears for module 3, 4, 5 and 6 for the power 10 HP, 15 HP and 20 HP respectively can be inferred from Tables 6 to 14 and Graphs 1 to 9. This process is repeated for different modules 3, 4, 5, 6 with all the 9 Gears in the Epicyclic Gear Train. All the results are tabulated and graphs are plotted accordingly from Table. It is observed that in the Sun Gears Z, X, Y , the least loads can be seen at the module 6, but of the plant gears and annuluses the least loads were observed at module 3.
On further examination of the loads for the gears which were plotted from Table 6 to 14 and Graphs 1 to 9, we can notice that the Wear tooth load Ww for all the gears in the gear train is higher than the Dynamic tooth load Wd , and the Dynamic Tooth load Wd is less than Static tooth load Ws for all the gears in the system.
As this condition has to be true for safety against tooth failure, thus we can state that the design is safe. We can observe in Graphs Z, Y and X that the loads are decreasing as the module is increasing and the least load is observed on module 6, as those are the sun gears in the gear train.
Also it is observed that the rest of the gears and annulus in graphs K, R, L, Q, N and P that the loads are increasing as the module increases and the lease load is observed on module 3. Furthermore it is also observed that in Graphs Q, P and R, the wear tooth load is greater than the static tooth load which is why the teeth of the annuls should be of a higher wear resistant www. Thus as the design satisfy the condition that Static Tooth Load Ws should always be greater than the Dynamic Tooth Load Wd also the Wear tooth load Ww should not be less than the Dynamic tooth load Wd , the proposed design is safe and the least load conditions being at the least module 3, in this condition is preferred for the annulus design and the planet gears where as a higher module 6, in this condition is preferred for the sun gears design for all power levels.
It is also known as pitch diameter. Pressure angle is the angle between the common normal at the point of tooth contact and the common tangent to the pitch circle. It is the surface of the imaginary rolling cylinder that the toothed gear may be considered to replace. The base circle of involute gear is the circle from which involute tooth profiles are determined. The circular pitch is the distance measured on the circumference of the pitch circle from a point of one tooth to the corresponding point on the next tooth.
It is denoted by Pc. Clearance is the difference between the dedendum of one gear and the addendum of the mating gear. Total depth is the radial distance between the addendum and the dedendum of a gear. It is equal to the sum of addendum and dedendum. It is the radial distance from the addendum circle to the clearance circle. It is equal to the sum of the addendum of the two meshing gears.
Tooth space is the width of space between the two adjacent teeth measured along the pitch circle. Backlash is the difference between the thickness of a tooth and the width of a tooth space on which it meshes. So now, we hope that we have clear all your doubts about Gear Nomenclature. We have also a Facebook community for you guys. If you want, you can join our community, here is the link to our Facebook group. If you like our article then please share it with your friends.
If you have any questions about any topic you can ask in the comment section. Email Address. Saif M. He completed his engineering studies in and is currently working in a large firm as Mechanical Engineer. He is also an author and editor at www.
Important circle in gear terminology which one Addendum circle Dedendum circle Pitch circle Base circle. All definitions are very easily understand after one time reading any student easily understand to this after the reading. Notify me of follow-up comments by email.
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