Planetary Gear Trains are extensively used for power transmission and are the most critical component. This report focuses on the designing and analysis of a planetary gearbox for an SAE BAJA All-Terrain Vehicle (ATV). The conventional two-stage speed reduction gearbox is bulkier and has a high volume to power ratio. A planetary gearbox gives the best balance between weight and power to be transmitted. For the design procedure standard method is utilized. Based on conventional equations gear calculations are performed and subsequently, CAD modeling for various parts is done. The analysis for each component is performed and checked for its stresses. The transmission shafts and bearings are designed using the standard force equations. In addition, the design and analysis of gearbox casing is performed and the complete assembly is checked for interferences. This report also presents the advantages and limitations of planetary gear train over other transmission systems. The comparison of planetary gear system with compound spur gear system is done on the basis of volume and weight, ease in manufacturing, assembly and disassembly and aesthetical viewpoint.
Planetary gear Train also referred to as epicyclic gear Train consists of three elements sun gear, planet gear, and ring gear. Sun gear is located at the centre that transmits torque to planet gears orbiting around the sun gear. Both systems are located inside the ring gear. In the toothed formation, sun and planet gears are in external meshing while planet gears and ring gear are internally meshed. The planetary gear train is found in many variations and arrangements to meet a broad range of speed-ratio in the design requirements. Now, industrial applications demand high torque in a compact (a high torque/volume) and light (a high torque/weight ratio) package. In a planetary gear train, torque density can be increased by adding more planets through multiple gear mesh points. This means a planetary gear with say three planets can transfer three times the torque of a similar-sized fixed axis standard spur gear system. The applied load to planetary gears is distributed onto multiple gear mesh points means the load is supported by N contacts (where N = the number of planet gears) increasing the torsional stiffness of the gear train by factor N. Hence it lowers the lost motion compared to similar size standard gear trains. Planetary gears with deep groove ball bearings are frequently used in applications in which high radial loads occur. Hence, they are used to develop a hub drive system for an automobile. Automated Guided Vehicles and Mobile Satellite Receivers are other applications of a planetary gearbox.
II. DESIGN OF GEAR BOX
A. Determination of Speed Reduction Ratio For Planetary Gearbox
For proposed application, a four-stroke cycle, air-cooled engine would serve the purpose. This segment has considered Briggs & Stratton (B&S) 10 HP overhead valve engine (OHV) intake Engine as a prime mover/Powertrain. This engine develops a maximum torque of 18.98 N-m at 2800rpm and a peak power of 10 HP at 3800 rpm.
The main objective of the transmission is to provide to the drive more than enough torque to the wheels from the engine. Enough torque means torque required to pull the driving wheels against the road loads.
To choose the transmission capable of producing enough torque to propel the All-Terrain Vehicle (ATV), it is necessary to determine the total tractive effort (TTE) requirement of the vehicle.
Following are the design parameters selected for the vehicle
Gross vehicle weight (car + driver) 170+70 = 240 kg
Weight distribution ratio =0.6
Maximum engine torque 18.98 N-m
1) The purpose of this project was to design a planetary gear train suitable for All-Terrain Vehicle (ATV) where space and weight constraints were the prime objectives.
2) In the designed planetary gearbox reduction ratio of 5:1 is achieved in a single stage rather than two stage in the compound spur gearbox for the same reduction ratio.
3) The weight of the planetary gear train is 2.8 kg less than the compound spur gearbox while the size reduction attained is 10%.
4) The proposed planetary gear train successfully meets the intended objectives.
 University of Manitoba SAE (UMSAE) Baja Transmission Design, Final design report, 12-05-2011, Project Advisors: Malcolm Symonds & Paul Labossiere. Names of Team Members: Brian J. Nuessle, John M. Bais, Steven N. Young, Qiankun Zhao
 Bernd-Robert Höhn, Karsten Stahl and Philipp Gwinner Light-Weight Design for Planetary Gear Transmissions? GEAR TECHNOLOGY, Sept. 2013, PP: 96-103
 Design and Analysis of Gearbox for SAE BAJA Competition Anjali Mukeshkumar Sah, Naved Anwar Husain Farooqui. International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 9 Issue 05, May-2020
 DESIGN OF TWO-STAGE PLANETARY GEAR TRAIN FOR HIGH REDUCTION RATIO Prabhakar Vitthal Pawar1, P.R. Kulkarni2. 1) M.E. (Design ), Mechanical Engineering, Walchand Institute of Technology, Solapur-413003, Maharashtra, India. 2) Professor, Mechanical Engineering, Walchand Institute of Technology, Solapur-413003, Maharashtra, India. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
 Design Analysis of Industrial Gear Box Casing- Balasaheb Sahebrao Vikhe
 Design and Analysis of an Epicyclic Gearbox for an Electric Drivetrain Timir Patel, Ashutosh Dubey, Lokavarapu Bhaskara Rao International Journal of Recent Technology and Engineering (IJRTE) ISSN: 2277-3878, Volume-8 Issue-3, September 2019  S. B. Nandeppagoudar, S.N.Shaikh, S. R. Gote, S. P. More, A. S. Chaudhari, N. R. Borse, S.H.Gawande, “Design and Numerical Analysis of Optimized Planetary Gear Box,” IOSR (Journal of Mechanical and Civil Engineering), March 2017