- Email: [email protected]
Ergonomic aspects of fork lift truck design
recommended practice. Unfortunately, the problem of actually measuring home lighting levels is not easily overcome since few occupiers have access to suitable photometers and the difficulty is greater where the intention is to measure luminance values. It is therefore of little practical significance that the values quoted for the maximum permissible brightness of artificial light sources have suffered an inaccurate conversion into metric units. The values given as 6.85 cds/m 2 and 34 cds/m 2 should in fact read 3 100 cds/m 2 and 15 500 cds/m ~ respectively. This error is a source of great potential confusion to any person who wishes to consider the interaction of illumination level, reflection factor and luminance as a basis for producing an adequately lit and comfortable interior. Apart from this the main criticism which one might level at this publication is that the various topics seem to be treated in a somewhat inconsistent order. For example, it would be preferable to outline the causes of discomfort and disability glare before discussing the role of windows and daylight design. For the reader who wishes to gain a better understanding of the ergonomic principles governing lighting design there are texts which deal with this subject in greater depth. For the individual who wishes to tackle a problem arising from the lighting of a domestic interior, this Design Centre Publication should prove a stimulus to improvement with relatively sophisticated information which takes account of human capacities.
Susan Harker Environment and human efficiency E.C. Poulton. Springfield II1.: Thomas, 1970. 328 pages. $15.50
This is a remarkable compendium of laboratory research on the effects of environmental factors on human performance. Dr. Poulton has collected about 300 references, covering a broad interpretation of the term environment. Thus, we find discussed the "familiar" stresses of heat, cold, acceleration, vibration, noise and poor visibility; in addition, however, there are chapters on personal threat, isolation, prolonged vigilance, bursts of speed, simultaneous tasks, sleep disturbances, physical exercise, decompression, compression, weightlessness, motion sickness, radiation, drugs and poisons, and old age. A final chapter is devoted to the pioneer studies in the increasingly important area of combinations of environmental~tresses. Each chapter on a specific environmental factor begins with a short summary, is concerned mainly with relating and interpreting the results of laboratory experiments, and ends with recommendations for avoiding the stress or for reducing its effects. Sometimes these final sections provide a useful guide to the many interesting facets of a practical situation, but in other chapters they turn out to be simple homespun recipes which contrast strangely with the precision of the relevant experiments ("Severe personal threats should be avoided where possible." ....... "A person should not be expected to take violent exercise and also carry out a task which needs an efficient brain." ....... "Intermittent noise is distracting.") However, as observed already, these chapters provide a comprehensive account of experimental research on environmental effects. Moreover, the
58
AppliedErgonomics March 1972
organisation and classification of the material provides a useful structure for discussing the environments in which people perform tasks, and one is introduced to most of the technical terms and concepts. I have been careful to emphasise that the material is almost exclusively derived from laboratory research, for this is an important consideration for most readers of Applied Ergonomics. There are very few references to studies of realistic tasks, even within the experimental laboratory; more often than not, experimental subjects have worked with those old favourites of the experimental psychologist, such as tracking tasks, short-term memory problems and serial reaction-time tests. There are even fewer cases of observational studies in practical settings, which might demonstrate that environmental conditions do influence the performance of man-machine systems. I do not underestimate the difficulties of such investigations, nor do I suggest that there are numerous examples which Dr. Poulton has ignored, but I think it important that research workers should recognise explicitly the gap between their carefully controlled laboratory situations and the real outside world. Chapanis (1967)has drawn attention consistently to these problems, and most ergonomists are only too well acquainted with them, but here Dr. Poulton makes no mentionat all. Indeed, sometimes he seems more intent on increasing the 'sensitivity' of an experimental task, so that it will be influenced by a change in environmental conditions, rather than reflect an activity of some practical importance. Of course, this controversy will rage always between experimental psychologists and ergonomists; in this case it serves to emphasise the difficulties in the way of direct application to practical contexts. The rest of the book the first four chapters, in 41 pages - is devoted to an extremely brief review of some theoretical and methodological issues. A far too superficial treatment is given to the topic of "Arousal", which is referred to often in later chapters. Statistical significance is allocated only two short paragraphs: Poulton consistently uses the adjective 'reliable' rather than 'significant', and while this is probably more expressive it may well cause confusion because of the almost universal convention of describing 'significant' differences between experimental conditions. In summary, this is an impressive book as a comprehensive review of experimental research; as a handbook for practitioners in real-life situations it has several limitations, resulting from our failure so far to draw together laboratory investigations and the needs of the applied world. Chapanis, A. 1967 Ergonomics, 10, 557-578. The relevance of laboratory studies to practical situations.
D. Whitfield Ergonomic aspects of fork lift truck design 1.
Review of current practice
R.W. Astley, R.H. Lawton. National Materials Handling Centre. 1971.64 pages. Members £3, non-members £5
This report is the first one issueo 0y the National Materials Handling Centre on the research work being carried out under their auspices at the Department of
Engineering Production, Birmingham University. It is in the nature of an introduction to the subject, and concentrates on outlining the problems and reviewing the relevant research carried out. It is not the kind of report which can be recommended to a design engineer who is in the process of designing a new machine although it will clearly show him the various options which are open.
The third section gives the results of a survey on the control layouts of the fork lift trucks of nine manufacturers. It shows the lack of standardisation between the different makes which hampers the transfer of drivers from one type of truck to another, and increases the likelihood of errors when a driver who has been trained on one make of machine is transferred to another with a different control layout.
The first section of the report is a review of research carried out on the design of hand and foot controls, seating, and the use of safety devices. The work covered is almost all concerned with fork lift trucks and similar devices. Problems could have been found, however, in the literature concerned with cranes, locomotives and motor vehicles.
The reduction of errors and, thus, injuries or accidental damage must be the main reason for giving more attention to ergonomic matters. Unfortunately, it appears that there is little real information on how fork lift truck accidents arise.The usual method of collecting statistics pays little attention to ergonomic aspects. It is to be hoped that the investigations will try, through their contacts, to get a better reporting system based on the analysis of errors a n d t h e ways in which they occur.
The second section outlines and comments on the various international and British standards for the design of industrial trucks. It illustrates the constant dilemma of whether standards are to lay down detailed rules which can be slavishly applied, or whether they should rely on stating the general principles which have to be adhered to. Although the former may be easier for designers to follow it is difficult to state the qualifications which apply to the results of experimental studies. Also, any real life design must involve a compromise between differing principles, and expert knowledge is often necessary to know which principles can be relaxed.
It is also hoped that in the final report of the project an analysis will be made of the system in which the fork lift truck is to work and the role of the operator within that system. This should enable the final recommendation to be in a form which will aid the designer in his job.
R. G. Sell
Methodology Proceedings of the Symposium held at Kyoto, Japan, September 1969
in
Human Fatigue Assessment
Edited by K. HASHIMOTO,K. KOGI and E. GRANDJEAN 250 x 176 m m • 232 pp • cloth 0 85066 049 1
In definition and application the term "fatigue" has a variety of meanings. The papers of the K y o t o Symposium dealt with the problems and methods of measuring general fatigue in industrial conditions. Available from your Bookseller or directfrom
£3.50
net.
postage extra
m TAYLOR
&
FRANCIS
LTD
International Scientific Publishers 10-14 Macklin Street, L o n d o n WC2B 5 N F
Applied Ergonomics March 1972
59
Susan Harker Environment and human efficiency E.C. Poulton. Springfield II1.: Thomas, 1970. 328 pages. $15.50
This is a remarkable compendium of laboratory research on the effects of environmental factors on human performance. Dr. Poulton has collected about 300 references, covering a broad interpretation of the term environment. Thus, we find discussed the "familiar" stresses of heat, cold, acceleration, vibration, noise and poor visibility; in addition, however, there are chapters on personal threat, isolation, prolonged vigilance, bursts of speed, simultaneous tasks, sleep disturbances, physical exercise, decompression, compression, weightlessness, motion sickness, radiation, drugs and poisons, and old age. A final chapter is devoted to the pioneer studies in the increasingly important area of combinations of environmental~tresses. Each chapter on a specific environmental factor begins with a short summary, is concerned mainly with relating and interpreting the results of laboratory experiments, and ends with recommendations for avoiding the stress or for reducing its effects. Sometimes these final sections provide a useful guide to the many interesting facets of a practical situation, but in other chapters they turn out to be simple homespun recipes which contrast strangely with the precision of the relevant experiments ("Severe personal threats should be avoided where possible." ....... "A person should not be expected to take violent exercise and also carry out a task which needs an efficient brain." ....... "Intermittent noise is distracting.") However, as observed already, these chapters provide a comprehensive account of experimental research on environmental effects. Moreover, the
58
AppliedErgonomics March 1972
organisation and classification of the material provides a useful structure for discussing the environments in which people perform tasks, and one is introduced to most of the technical terms and concepts. I have been careful to emphasise that the material is almost exclusively derived from laboratory research, for this is an important consideration for most readers of Applied Ergonomics. There are very few references to studies of realistic tasks, even within the experimental laboratory; more often than not, experimental subjects have worked with those old favourites of the experimental psychologist, such as tracking tasks, short-term memory problems and serial reaction-time tests. There are even fewer cases of observational studies in practical settings, which might demonstrate that environmental conditions do influence the performance of man-machine systems. I do not underestimate the difficulties of such investigations, nor do I suggest that there are numerous examples which Dr. Poulton has ignored, but I think it important that research workers should recognise explicitly the gap between their carefully controlled laboratory situations and the real outside world. Chapanis (1967)has drawn attention consistently to these problems, and most ergonomists are only too well acquainted with them, but here Dr. Poulton makes no mentionat all. Indeed, sometimes he seems more intent on increasing the 'sensitivity' of an experimental task, so that it will be influenced by a change in environmental conditions, rather than reflect an activity of some practical importance. Of course, this controversy will rage always between experimental psychologists and ergonomists; in this case it serves to emphasise the difficulties in the way of direct application to practical contexts. The rest of the book the first four chapters, in 41 pages - is devoted to an extremely brief review of some theoretical and methodological issues. A far too superficial treatment is given to the topic of "Arousal", which is referred to often in later chapters. Statistical significance is allocated only two short paragraphs: Poulton consistently uses the adjective 'reliable' rather than 'significant', and while this is probably more expressive it may well cause confusion because of the almost universal convention of describing 'significant' differences between experimental conditions. In summary, this is an impressive book as a comprehensive review of experimental research; as a handbook for practitioners in real-life situations it has several limitations, resulting from our failure so far to draw together laboratory investigations and the needs of the applied world. Chapanis, A. 1967 Ergonomics, 10, 557-578. The relevance of laboratory studies to practical situations.
D. Whitfield Ergonomic aspects of fork lift truck design 1.
Review of current practice
R.W. Astley, R.H. Lawton. National Materials Handling Centre. 1971.64 pages. Members £3, non-members £5
This report is the first one issueo 0y the National Materials Handling Centre on the research work being carried out under their auspices at the Department of
Engineering Production, Birmingham University. It is in the nature of an introduction to the subject, and concentrates on outlining the problems and reviewing the relevant research carried out. It is not the kind of report which can be recommended to a design engineer who is in the process of designing a new machine although it will clearly show him the various options which are open.
The third section gives the results of a survey on the control layouts of the fork lift trucks of nine manufacturers. It shows the lack of standardisation between the different makes which hampers the transfer of drivers from one type of truck to another, and increases the likelihood of errors when a driver who has been trained on one make of machine is transferred to another with a different control layout.
The first section of the report is a review of research carried out on the design of hand and foot controls, seating, and the use of safety devices. The work covered is almost all concerned with fork lift trucks and similar devices. Problems could have been found, however, in the literature concerned with cranes, locomotives and motor vehicles.
The reduction of errors and, thus, injuries or accidental damage must be the main reason for giving more attention to ergonomic matters. Unfortunately, it appears that there is little real information on how fork lift truck accidents arise.The usual method of collecting statistics pays little attention to ergonomic aspects. It is to be hoped that the investigations will try, through their contacts, to get a better reporting system based on the analysis of errors a n d t h e ways in which they occur.
The second section outlines and comments on the various international and British standards for the design of industrial trucks. It illustrates the constant dilemma of whether standards are to lay down detailed rules which can be slavishly applied, or whether they should rely on stating the general principles which have to be adhered to. Although the former may be easier for designers to follow it is difficult to state the qualifications which apply to the results of experimental studies. Also, any real life design must involve a compromise between differing principles, and expert knowledge is often necessary to know which principles can be relaxed.
It is also hoped that in the final report of the project an analysis will be made of the system in which the fork lift truck is to work and the role of the operator within that system. This should enable the final recommendation to be in a form which will aid the designer in his job.
R. G. Sell
Methodology Proceedings of the Symposium held at Kyoto, Japan, September 1969
in
Human Fatigue Assessment
Edited by K. HASHIMOTO,K. KOGI and E. GRANDJEAN 250 x 176 m m • 232 pp • cloth 0 85066 049 1
In definition and application the term "fatigue" has a variety of meanings. The papers of the K y o t o Symposium dealt with the problems and methods of measuring general fatigue in industrial conditions. Available from your Bookseller or directfrom
£3.50
net.
postage extra
m TAYLOR
&
FRANCIS
LTD
International Scientific Publishers 10-14 Macklin Street, L o n d o n WC2B 5 N F
Applied Ergonomics March 1972
59