Executive Summary

Executive Summary

Our Engineering team has been contracted to design a power transmission for an industrial saw. The objective of the design is to take the mechanical power supplied by a motor and reduce the input rotational speed by a means of a gear system to meet the output speed specified by our client. Considering the need to maximize the speed output, torque, durability and longevity of the gear system as the main concern, our Engineering team decided that a planetary gearbox would be the best to meet the client’s needs. Therefore, the main purpose of this report is to communicate the design procedures of the planetary gearbox system, efficiency findings, and recommendations of our team concerning the requirement of our client.

The planetary gear combination: With factors such as power output requirement, as stated by the client, and size constraints put into consideration to find the satisfactory gear combinations over a range of gear module from 2 to 4, MATLAB programme was conducted by our team with the help of Mechanical Engineering Design by Shigley to produce a gearbox system with a shaft, Sun gear, and three planetary gears.

The planetary gearbox design: The planetary gearbox system is designed to accommodate approximately 350mm in diameter and 750mm thickness. It is characterised by three sections; shaft, whose design was left to be done after more research has been conducted; bearings of the shaft with dimension of OD = 52mm and ID =25mm was selected with 15mm wall thickness minimum allowance allowed; Sun gear of 110mm in diameter accommodating 40 teeth, and three planetary gears of 71.5mm in diameter and 26 teeth each. This is to run at module of 2.75.

The planetary gearbox system requirements: With an output power of 15.4KW; as required by the client; in mind, our team decided that to produce this gearbox system with the above output power, a transverse force of 2.18KN and pressure angle force of 793.46N acting on the Sun gear is required to produce a transverse force of 726.7N and pressure angle force of 264.5N on the each planetary gear. The force input to the Sun gear is assumed to be distributed amongst the three planetary gears evenly. To make this force requirement on the planetary gears possible, a Shear Force input of 13.81 Mpa is required to act on the Shaft key way that would the produce the above stated force requirement on Sun gear. Therefore, the team decide to select “K34 E2W21” motor with 18.5KW power output and 1475 PPM.

The planetary gearbox system expected output results: The power out requested by the client was the chief concern but a number of factors had to be considered to ensure the system meet AGMA standards. These factors included the durability and effectiveness of the system, directly calling for strength of the system to withstand the power input of 18.5KW. Therefore, 1040 steel and gear widths selected were suitable to withstand the Sun Gear’s 15.48Mpa, Planetary Gear’s 28.45Mpa, and Ring Gear’s 54.91Mpa maximum bending stress. This reflect on the strength and ability of the gear tooth of planetary gearbox system to withstand the maximum bending stress of 75.48Mpa calculated to be encountered whilst the system is operational as supported by Levis equation.