Design Project -
Introduction:
You work for a company that manufactures wood chipping machines. A new model has just been released, powered by a 25 horsepower electric motor (previously the largest model produced by the company featured a 20 hp gasoline engine). It has been identified that the previous design routinely suffered failures at the output shaft, so particular attention must be paid in the new design. The wood chipper machine is subject to mostly low amounts of shock, with occasional moderate shock when nails and other metal accidentally pass through the chipper. Use the Power Transmission Case Study (Section 18 in Shigley's Mechanical Engineering Design) as a basis for the procedure of the design. The project should be completed individually or in a group of two.
Assignment:
Design the output shaft (with specifications of the related components including the spur gear and the rolling element bearings) for the gear train. The specifics for the application are as follows:
- The input power to the wood chipper is 25 hp.
- Input speed: 1780 RPM
- Output speed (of gearbox): 65 RPM
- Duty: Low shock levels (with occasional moderate shock)
Notes:
- Please specify a real bearing part number for the bearings selected in the design process. You can use bearing manufacturer's catalogues on their websites (SKF or NTN etc.)
- Provide all calculations (as is done in the case study) and clearly state any assumptions you make! Hand written calculations are acceptable, as long as they are neat and presented professionally.
- The solution (report) should be self-contained.
- The final drawing for the shaft may be done by hand (again, if done properly).
Special Note:
Stress analysis and deflection checks are not required for this design project; however they should not be neglected in real life design applications!