A survey of the optimal handle position for boxes with different sizes and manual handling positions

Handles on objects are very important for enhancing the safety and efficiency of manual handling for people who use them. In this study, four different prototype boxes with auxiliary handles were designed to determine the optimal handle position of a box based on the evaluated user preferences and body part discomfort (BPD). Twenty male students participated in the experiment. Likert-5 point summated rating was applied to evaluate user preferences for the provided boxes with handles in upper, middle, and lower positions, in four different sizes and manual handling positions. Ten additional subjects were asked to indicate their BPD on a body chart after performing a similar experiment. The results show that the subjects preferred the upper part of the handle on a small box regardless of handling position; while the mid to upper parts of the handle on a big box were preferred for handling above the waist height. BPD also indicated that an upper handle was less stressful for a relatively smaller box than a big one; and mid to upper handles were less comfortable for a big box. The optimal handle positions depending on box size and handling position were suggested based on the results of the evaluation. It is thus recommended that a box provides a handle according to its relevant position, depending on size and manual handling condition, to reduce the musculoskeletal stress and in turn to increase user satisfaction.     

Handles for manual materials handling

The humble handle is one device available to designers of products and packages to improve the coupling between a human operator and the load he/she has to lift, hold or carry. Studies of handle design show that handles can help and that some are better than others but agreement on how handles should be studied, parametric values of 'optimum' handles, and even criteria for handle choice is low. Design parameters are reviewed, two new experiments on handle diameter are presented and a guide for handle designers is provided.     

Usability of manual handling aids for transporting materials

Manual transport aids (trucks and trolleys) are in widespread use throughout most industries, but their use does not always result in the anticipated reduction of workload or musculoskeletal stress. A survey of users has shown that many of the aids currently used are poorly designed or inappropriate for the tasks performed. The information gained during the survey has been analysed to identify the most important design features and to provide guidance for their selection and evaluation, in order to ensure that aids are suitable for the tasks for which they are used and that they are effective and safe. It is clear that the first stage in establishing design criteria and guidelines should be developing an understanding of the task requirements and environmental conditions under which materials have to be transported in industry.     

Evaluation of perceived and self-reported manual forces exerted in occupational materials handling

The main objective of the study was to evaluate the ability of workers to reproduce simulated manual work forces correctly and to quantify these forces in Newtons (N) by means of self-reports. Fourteen male and 14 female workers participated in the study. Three experiments were carried out. In the first experiment, the ability to reproduce the magnitudes of simulated manual forces occurring in daily work and to estimate these forces in Newtons was tested. A specially designed force-measuring device was used for this purpose. In the second experiment, the subjects estimated the weights of five boxes ranging from 1 to 30 kg. In the third experiment, the subjects were asked to produce five predetermined push and pull forces ranging in magnitude from 10 to 300 N on to the handle of the force-measuring device. The ability to reproduce the magnitudes of manual forces when simulating four familiar work tasks was good (the intraclass correlation coefficients ranged from 0.75 to 0.95). The ability to quantify these forces in Newtons was not as good (the product moment correlation coefficients ranged from 0.21 to 0.69). When the subjects estimated the weights of boxes they underestimated the weights. When they produced predetermined push and pull forces they exerted higher forces than expected when low force levels were requested and lower forces when high force levels were requested. However, the forces were correctly ranked. In summary, simulation of the manual push/pull forces used in familiar work tasks seemed to offer sufficient reproducibility to be worth testing for validity. Self-reports, used without previous training or without known 'reference forces', seemed to be very rough when the aim was to estimate in kg or Newtons. However, the fact that individuals could rank the forces correctly opens a potential for refinement of self-reports as a method for quantifying manual forces in objective terms, e.g. kg or Newtons.     

An on-line microcomputer-based respiratory monitor for manual materials handling

The main objective of the present study is to develop a low cost microcomputer-based respiratory system that is capable of computing the oxygen consumption and minute ventilation of individuals engaged in manual materials handling on an on-line basis. The design, specifications, and merits of the system are given. The software package developed was written in assembly language for the IBM AT personal computer.     

A knowledge-based system for the design of manual materials handling

The purpose of this paper is to develop and test an expert system for the design of new and existing repetitive manual materials handling (RMMH) tasks. For new jobs, the expert system provides recommendations on the maximum acceptable weight to be handled under a variety of worker and task variables. For existing jobs, the expert system provides possible solutions to the design of RMMH tasks if the weight handled on the job is greater than the recommended one. The expert system was implemented on an IBM PCXT personal computer. Two examples on how to utilise the expert system in designing new and existing jobs are given.     

Evaluation in industry of a draft code of practice for manual handling

This paper reports findings from a study which evaluated the draft New Zealand Code of Practice for Manual Handling. The evaluation assessed the ease of use, applicability and validity of the Code and in particular the associated manual handling hazard assessment tools, within New Zealand industry. The Code was studied in a sample of eight companies from four sectors of industry. Subjective feedback and objective findings indicated that the Code was useful, applicable and informative. The manual handling hazard assessment tools incorporated in the Code could be adequately applied by most users, with risk assessment outcomes largely consistent with the findings of researchers using more specific ergonomics methodologies. However, some changes were recommended to the risk assessment tools to improve usability and validity. The evaluation concluded that both the Code and the tools within it would benefit from simplification, improved typography and layout, and industry-specific information on manual handling hazards.     

Experiments on wrist deviation in manual materials handling

One potential hazard in manual materials-handling (MMH) jobs is the wrist deviation required when a container is moved. Container handles may help control this deviation, but if container handles are to be designed to fit the operator, an evaluation of the effect of wrist deviation on MMH tasks is required. After a pilot experiment, a one-handed holding task was used to impose five wrist deviations on the subject, ranging in equal steps from 20° ulnar to 20° radial. Two weights of container (9 and 13 kg) were tested. Measurements of heart rate, psychophysical variables and angles of the hand and arm were taken on 15 male and 15 female subjects. No significant gender effects were found but changes in imposed deviation were equivalent to a 16% change in box weight. Radial deviation proved worse than ulnar deviation. The hand and arm accommodated to the imposed deviation by deviating the wrist but mainly by allowing the box handle to slip within the hand.     

A comprehensive data base for the design of manual materials handling

The main objective of the present paper is to provide a comprehensive data base of the material handling capabilities of the industrial work force. The data base encompasses the following: (1) five different types of manual materials handling activities, namely, lifting, lowering, carrying, pushing, and pulling, (2) worker variables (e.g., sex), and (3) task variables (e.g., frequency, and container size). The data base was developed for the IBM personal computer using the software package DBASE III PLUS.     

Optimum handle positions in a box-holding task

Ten combinations of handle position, four symmetric and six asymmetric, were tested in a static holding task. Ten male subjects held each of 10 boxes (two weights × five sizes) at waist level with each handle position. Biomechanical, physiological and psychophysical measures were taken. Handle position was highly significant for all measures, but handle position effects varied depending upon the measure used. Two groups of effects were found, one biomechanical and the other physiological and psychophysical with little intercorrelation between the groups. The interface between the body and the container emerged as an important part of the holding task with friction and reaction forces comparable to the box weight. In general, the best handle combinations on all measures were those which combined strong horizontal and vertical stabilizing components.     

Symmetric and asymmetric manual materials handling, Part 2: Biomechanics

Earlier studies of the biomechanics of handle placement and angles on boxes in Manual Materials Handling have been limited to sagittally symmetric tasks. This study extends the results to a palletization/depalletization task with considerable asymmetric movement. Part 2 shows how body posture, hand/handle interface, and disc compressive force change in this asymmetric task. The results were not too different from the earlier studies of symmetric tasks, except that a 'traditional' handle position in the upper part of each lateral face (the 2/2 position) proved more effective than had been anticipated.     

Evaluation of alternative materials handling systems

This paper addresses the development of a simulation model to assist in the selection of a new materials handling system for the service and repair group of a major electronics company.     

The cost/accuracy approach: a method for selecting filming rate for manual materials handling activities

This paper presents a method for determining filming rate for developing kinetic biomechanical models of manual materials handling activities. Using a high-speed camera, manual lifting activities were filmed at 500 frames per second. Different framing rates were then simulated by skipping one or more film frames. The data analysis indicated that selection of filming rate on the basis of cost and accuracy trade-off is superior to existing framing rate selection criteria. The proposed method can be used for other similar activities.