In this project, we as a group designed a gearbox to run with set of gears based on specific power input, run speed, and gear ratio as well as some other set design constraints. Our group's design requirements were:

 

• Power Input: 10.5 hp

• Gear Ratio: 7.2 with 1% variation

• Speed: 1800 rpm

• The delivered power will be in the range of 15 ~ 30 hp.  The power source and driven device can be treated as “light-shock” loading factor of 1.5. 

• The gearboxes will consist of a single-reduction spur gearbox with the gear ratio 7.2. For the spur gear, the pressure angle will be 20 degrees.

• It is recommended that a single-row ball bearing will be used for the single-reduction spur gearbox.  

• The design life for bearing will be 4, 000 hours.  

• For the shaft, the factor of safety is 2.25 for the static design and 1.25 for the fatigue design. For the fatigue design of the shaft, it is assumed that endurance limit will be used.

• The reliability index will be 0.90.  

• The connection between the power source, driven device and the designed single-reduction spur gearbox will be through mechanical keys.   

• The hub length for the input shaft for the engine might be at least 1.5”  

• The hub length for the output shaft for the working device might be at least 2”

Under these design constraints, we calculated required values such as bearing load, tooth stress, torque, and moments utilizing an Excel spreadsheet. These calculations were used to determined shaft geometry (i.e. minimum diameter and length) while simultaneously calculating failure due fatigue and static stress to make sure all constraints maintained valid. We then selected gears and bearings from online catalogues based on Excel calculations. Following this, we created SolidWorks parts and drawings for the shafts as well as ran FEA frequency and deflection simulations. At the end of the project, we wrote a technical report consisting of required elements such as free body diagrams, tables of calculations, annotated drawings, and part numbers of selected gears and bearings. This report can be read below.

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