Ergonomic modification and performance evaluation of a shoulder-strapped brush cutter

Ergonomic studies were carried out on selected shoulder-strap brush cutters to evaluate some deficient ergonomic factors associated with their operations. These deficiencies were used as basis for modification. Contextual interview and field interactions were used to obtain ergonomic data that are descriptively analyzed. Results of ergonomic assessment shows that operators are subjected to pains around the neck, shoulders, upper arm and fingers which are largely traceable to shoulder-strap-long-time operation, exposures to prolonged mild vibrations, repetitive arm supination-pronation-swings during operation, exertion due to prolong suspension of the weight of the machine. Based on these outcomes, modifications were made on machine which include removing the machine weight from shoulder to a push-carrier that bear the machine weight, height adjustment mechanism to regulate the height of cut, reduction of the transmission assembly length from 1500mm to 300mm for effective maneuvering and orientation of the handle for ease of control. Performance evaluation shows that the modified machine was ergonomically acceptable and user friendly with excellent mowing quality.