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Abstract. In this paper a driving linkage is designed with a fairly simple proce-dure for a fairly simple structure for implementation in a rural water pump in Andes regions. The aim is to provide a mechanism solution that can be easily implemented for comfort and efficiency issues with proper adjustments and avail-able materials in rural environments with very limited resources. Keywords: Rural Machines, Design, Linkages.35981
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1 Introduction Rural machines are needed in places where people can have difficulties not only to buy machines but mainly to operate them with industrial-like facilities, [4]. Thus, in general rural machines are constrained in design, material, operation features to be systems that can be handled in rural fields with reduced power without any supporting environment. The design and operation of rural machines must be pos-sible so that the machine can be manufactured and assembled in rural places where they will be operated, without any technical support, [1, 3]. Consequently, main characteristics of a rural machine can be considered in a fairly simple struc-ture and human-sized operation with locally available materials. In addition, it is to note that the acceptance and use of rural machines strongly depends on how they are introduced within the social and anthropological frames of a specific rural community in order to respect and indeed integrate the cultural identity and life environment of the rural community, as stressed in the ITACAB report, [3]. In this paper a design procedure is outlined to conceive and size mechanisms for rural machines but to propose their improvements for better efficiency and ergonomics that can facilitate the acceptance and indeed the use in rural fields by operators without any technical background. Thus, a design procedure and per-formance characterization are proposed with handsome calculations as based on geometrical models and formulation. 2 A Water Rural Pump This specific case of study refers to a water pumping systems for small sized-water spring hole in its form that has been originally developed for application in rural areas in Andes region in Perù, Fig1. The pump is composed of a rope, piston heads, an upper wheel with crank, a bottom underwater small wheel with weight, and a pipeline. All components can be made with natural materials, like wood from local trees and other common available materials. The piston heads are at-tached along the rope at an interval of 1 m or less, so that they can push the water ahead to the top when the rope is run inside the pipeline with suitable diameter with respect to the size of the piston heads. With such a design a prototype, Fig.1, was tested to prove a water flow of about 1.5 litre per revolution with a manpower of 5 W.
a) b) Fig. 1 A design of a rural water pump as applied in Andes areas of Perù: a) diagram and parameters of a current solution; b) a prototype of a current solution at the Pontifical Catho-lic University of Perù In Fig. 2 experimental results are reported to show the action force of a human operator in driving the water pump through the crank rotation. Results are illus-trated as function of number of turns by an operator as measured at given crank angles during each rotation. A peak force value is experienced as 19.80N where as the average maximum force during the operation can be considered with about 11N near the upward position of the crank. A design procedure for the system development in Fig.1 was based preliminar-ily on the rules in the German standard VDI 2222-1, as outlined in [1], and consists on evaluation criteria for considering both local and technical require-ments, computation efforts for identification of morphological matrix and func-tions structures for the specific machine, and finally calculations for an optimal design. In this case of rural machines for Andes areas main attention has been addressed to local requirements for identification not only technical constraints for design issues but mainly for feasible expectations for a proper use and understanding from potential users. Fig. 2 Measured operator action during crank revolution of the upper wheel for rural pump in Fig.1 Direct experiences on site have shown that main problems are related to the ac-ceptance of the water pump machine with proper functioning. Reluctance has been experience as due to understanding the technical system by potential users both for their limited education (not only in technical matters) and capability of operating the system at high altitude with proper action in not even long operation. By let-ting potential users contribute in the development but assembling and installation of a rural water pump will obtain both acceptance and understanding for a proper use of the system, as successfully experienced in a similar case with another rural machine, [1]. This requires to conceive the system fairly simple with components that can be easily adjusted both in materials and manufacturing with range of tol-erance for the final result. The latter aspect, e. g. proper action and comfort in operating the water pump by manual operation, is the problem that is addressed with the solution proposed in this paper. The current solution in Fig.