Human powered press for producing straw bales for use in construction during post-emergency conditions

The straw bale construction technique is considered one of the most appropriate for the improvement of housing conditions in developing countries and for the reconstruction in post-emergency situations. In this environment, no electricity or other energy sources are available; for this reason, straw bales have to be produced by means of a human powered press. This paper presents the designing process of a manual press, that is a key tool for the objectives introduced above. Following definition of the machine architecture and the actuating mechanism (slider-crank), a design method based on energy considerations is introduced. Given the mechanical properties of straw, described by a simplified linear model, and the maximum work that a human operator can do, applying the designing method, it was possible to obtain the main functional parameters of the machine, such as the pressing piston stroke, and the length both of the connecting rod and of the crank. The method was experimentally validated and a prototype assembled and used for the production of infill bales in the construction of a warehouse in Haiti.