Ergonomic Bench to Decrease Postural Risk Level on the Task of Changing Forklift's Brake Pads: A Design Approach

Ergonomic Bench to Decrease Postural Risk Level on the Task of Changing Forklift's Brake Pads: A Design Approach

Arturo Realyvásquez (Instituto Tecnológico de Tijuana, Mexico), Guadalupe Hernández-Escobedo (Instituto Tecnológico de Tijuana, Mexico) and Aide Aracely Maldonado Macías (Autonomous University of Ciudad Juárez, Mexico)
Copyright: © 2018 |Pages: 20
DOI: 10.4018/978-1-5225-5234-5.ch002

Abstract

Development of musculoskeletal disorders caused by awkward postures are present in tasks performed in small companies. Consequently, this chapter evaluates the postural risk level associated to the task of changing brake pads of a forklift, and proposes the design and the implementation of an ergonomic bench that helps to reduce this level of postural risk. As methods, postural risk level corresponding to the task was determined using REBA, whereas anthropometric analysis was developed, and axiomatic design and TRIZ methodologies were used to develop the proposed design. Results showed a REBA score of 8 (high-risk level). The final design is done of nylamid, and it contains some TRIZ principle, such as copying, extraction, and dynamicity. Respect axiomatic design, the bench meets some functional requirements, such as support the user's weight, avoid unsafety conditions, and be adjustable. With the TRIZ principles and functional requirements, this bench will help diminish postural risk level.
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Introduction

Most of the ergonomic assessment methodologies adopted in the manufacturing industry are implemented to assess ergonomic hazards in the production area (Tompa, Dolinschi, de Oliveira, Amick, & Irvin, 2010), yet other processes, such as machinery maintenance/repairs, material transportation, and/or plant cleaning, require similar ergonomic evaluations to ensure employee safety. To address this gap, this research takes place in a company that repairs and sells industrial machinery.

It is well known that maintenance and repairing tasks force employees to adopt awkward postures (Barros, Marçal, & Soares, 2015; Teymourian, Seneviratne, & Galar, 2016) and apply excessive force. In this sense, the maintenance technicians of the company wherein this study was conducted have claimed to experience discomfort when they change forklift brake pads. This task takes approximately one hour per brake, and to complete it, the technicians usually adopt awkward and long-lasting postures. According to the employees, the main musculoskeletal complaints experienced are in the back, the ankles, and the knees. Even though knee pads are worn, the employees claim these are not an effective solution to pain and discomfort. Figure 1 depicts the typical posture adopted by the employees as they change forklift brake pads.

According to the literature, awkward postures have a negative effect on employee health and performance. They can cause soft tissue injuries that favor the accumulation of metabolites and accelerate disc degeneration, which can ultimately lead to disc herniation (Roffey, Wai, Bishop, Kwon, & Dagenais, 2010). Also, awkward workplace postures can increase the risk of suffering from musculoskeletal disorders (MSDs) – such as osteoarthritis (da Costa & Ramos-Vieira, 2009; Gallagher, Pollard, & Porter, 2011) and fibromyalgia (da Costa & Ramos-Vieira, 2009) – and are strongly associated with low back pain (LBP) and whole-body vibration (Vandergrift, Gold, Hanlon, & Punnett, 2012).

As regards employee performance, awkward postures are less efficient than postures that keep joints near to a neutral posture (Gangopadhyay, Ghosh, Das, Ghoshal, & Das, 2010). Also, it has been argued that awkward postures force employees to apply more force than necessary to accomplish a particular task. Such excessive force in turn affects muscle loading and compressive forces on the internal vertebral disc.

Figure 1.

Posture adopted by employees during the task of changing forklift’s brake pads

Source: Prepared by the authors (2017).

The literature shows the need to improve the working conditions of those who adopt awkward and unsuitable postures to do their jobs. In the context of our research, one alternative to addressing this need is to design a bench, as an ergonomic work tool, to ensure that the technicians can change the brakes safely and comfortably. The importance of this bench relies on its advantages as an ergonomic intervention. Ergonomic interventions do not only reduce workplace hazards and increase employee safety; from a corporate point of view, they provide economic benefits, since they prevent companies from incurring additional costs (e.g. employee insurance) and increase employee retention, since workers feel and are safe.

Key Terms in this Chapter

Bench: A piece of furniture in which one or more people can sit to adopt a comfortable posture and decrease muscle fatigue.

Forklift: Vehicle used in the industry to transport material on pallets, which are supported by two forks of the forklift.

Body Dimensions: Distances of body segments measured between two defined points. For instance, the height of a person is the distance measured from the ground up to the vertex of the person in standing position.

Postural Risk: Risk derived by postural load supported by different body segments when a person adopts an uncomfortable body posture. This risk is proportional to the time posture is adopted, its frequency of occurrence, and its deviation level of neutral posture.

Ergonomic Design: Design that applies ergonomic tools, such as anthropometry, and allows objects to be adapted to human capabilities and limitations.

Adjustability: An object’s capability to adjust or adapt itself to the requirements and need of different users.

Percentile: In statistics, a position value that indicates the percent of ordered data that are below that percentile. For instance, the 5th percentile is the value under which 5% of data are.

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