DESIGN OF A PEDAL POWERED CONCRETE MIXER.

ABSTRACT:

This report covers a detailed design solution of a concrete mixer that is meant to be used in the small-scale construction industry. Readily available concrete mixers in the current market are either electric or fuel powered. The aim of this project was to design a concrete mixer that could be pedal powered. Whereas many pedal powered machines are operated by one person, this design was developed to allow operation by two persons. The prototype in this project is not only designed for efficiency of operation but also for cost efficiency. This would make it easy to commercialize upon completion. We had to ensure the mixer could be locally fabricated without compromising its quality and integrity.

The research done on and about the project, together with theoretical formulae guided the design process of the mixer. The design methodology used in this project followed 5 basic steps which included understanding the user’s need which helped us generate a product concept. We then defined the functional requirements of the mixer which guided us in coming up with design specifications and hence the conceptual design ideas. The conceptual design ideas provided us with preliminary sketches and drawings. Finally, we developed a detailed design solution for the mixer.

During the detailed design solution, we performed material selection for each component of the mixer. Then, breaking the design of the mixer into four 4 crucial component systems namely; Power system, support system, loading and offloading system, and the drum itself, we started our calculations by determining the necessary gear ratio that would reduce the standard human cadence to standard speed of revolution of small scale concrete mixers. We then analyzed the forces acting on the shaft supporting the drum. As a result of that, we were able to calculate the stresses and moments on the shaft whose values allowed us to determine a suitable shaft diameter and hence a value for batch capacity of the concrete mixer.