ABSTRACT
Uma negociação tripartite entre a Fundacentro, o Sindicato dos Empregados Rurais de Araraquara e a Usina Santa Cruz permitiu a realização do estudo sobre o uso dos equipamentos de proteção individual (EPI) e das ferramentas de trabalho durante a execução da atividade de cortar manualmente a cana-de-açúcar. A problemática se manifestou frente às estratégias utilizadas pelos trabalhadores para viabilizar o uso conjunto das ferramentas e dos EPI, prescritos como obrigatórios pela Norma Regulamentadora Rural nº 4 (Ministério do Trabalho e Emprego) e pelas normas internas da empresa. A principal estratégia desenvolvida pelos trabalhadores foi emborrachar o cabo do facão com o objetivo de minimizar o efeito da falta de aderência entre a luva de proteção e o cabo da ferramenta. A metodologia utilizada no presente estudo foi analisar qualitativamente, através da aplicação de questionários, quatro modelos de luvas junto a 47 trabalhadores, além de analisar quantitativamente o coeficiente médio de atrito estático (µ) desenvolvido entre as luvas e a madeira com que é confeccionado o cabo do facão. Os experimentos foram feitos com madeira limpa e emborrachada e com luvas novas e usadas. A pesquisa qualitativa apontou a luva de proteção de raspa de couro e nylon como a preferida dos trabalhadores, pelo conforto advindo do fato desta luva se ajustar bem às mãos, de não prejudicar os movimentos e não ocasionar danos às mãos. O coeficiente de atrito estático (µe) depende do tipo de luva, da condição da luva e do tipo de superfície.
This study on the personal protective equipment (PPE) and the tools used for the manual harvesting of sugar cane resulted from a tripartite negotiation between FUNDACENTRO, the Rural Workers Union in Araraquara, and the Santa Cruz sugar mill. The subject came out while workers were trying to adapt themselves to the set of tools and PPE (Personal Protective Equipment) demanded not only by the Regulating Standard Rural nº4 set by the Ministry of Labor and Employment, but also to their companies internal rules. One of their strategies to improve their gloves adherence to the handles of their knives was covering them with rubber. Four models of gloves were analyzed not only from the point of view of their quality, through questionnaires distributed to 47 workers, but also their quantity, through the average static friction coefficient (µ) produced by the gloves when holding the wooden knife handles. Clean wood and wood covered with rubber, new and used gloves were tested. The qualitative research showed that workers prefer gloves made of leather and nylon scrapings because they fit their hands comfortably, without causing aches or blocking their movements. The static friction coefficient (µe) is determined by the glove material, its condition and the kind of surface.
ABSTRACT
The effects of the surface friction of a grasped object on the regulation of grip force during holding tasks using a precision grip were investigated. Using a force transducer-equipped grip apparatus, the grip force and load force acting on the object were measured continuously while surface materials (silk, wood, suede and sandpaper) and load weights (0.98N, 1.96N, 2.94N, 4.90N and 9.81N) were varied. From the recorded data, the average static grip force, slip force, safety margin force and static friction coefficient were evaluated.<BR>It was found that both the slip force and safety margin force increased as the slipperiness of the object surface increased. Significant interactions between surface type and weight were observed in the slip force and static friction coefficient. The interaction effect resulted from the fact that the frictional relationships with the fingers changed according to both weight and surface conditions. This was considered due to the viscoelastic nature of finger skin. An increase in the safety margin force with surface slipperiness was considered due to psychological reaction, probably fear of dropping the object. Unexpected changes in surface conditions caused a greater safety margin force than trials without a surface change, which might also have been associated with psychological reaction to uncertainty of the new surface condition. A relatively large inter-subject variation was found in the slip force and safety margin force relative to slippery surfaces.