E.N. Corlett

The effects and measurement of working postures.

Postures are a necessary result of undertaking working activities but the constraints the impose on these activities are not overtly recognised. The forms which these constraints can take are discussed, as well as the likely outcomes for a worker arising from long held or frequently adopted postures. Methods for the recording and evaluation of postures and their effects are described. Research into the relationships between the extent of and holding times for postures and the effects of various recovery times are discussed. Where a maximal postural effort has a recovery period of twelve times the length of the time the posture was held, only about 80% of the initial performance can be expected. Full recovery requires rest periods in excess of 1200% of working time.

The design of direction finding systems in buildings.

The directory and sign-posting in a University building was investigated and modified. Tests were run of the existing system, and the proposed new system; after modifications from the tests the revised system is being installed. A technique for designing direction-finding systems in buildings is outlined.

The ergonomics of spot welders

The working situations of people working spot welding machines, both foot and power operated, are described and measurements of several machines and their performances are presented. From performance, discomfort and machine design analyses desirable modifications to the workplace are deduced and implemented. Subsequent measures taken over a period of two weeks of performance show increased output, reduced production costs and increased comfort for the operators.

Cross-modality matching as a subjective assessment technique

The paper presents the available forms of cross-modality matching (CMM) and discusses their fields of use. A particular emphasis of the discussion is on the applications of CMM in ergonomics, with the example of the perceived exertion rating scale due to Borg. Other uses for CMM are presented and the limitations and sources of error outlined.

Ramps or stairs: the choice using physiological and biomechanic criteria.

A study using eight subjects compared the O(2) consumption, heart rate and maximum knee joint angles when climbing stairs or ramps ranging in slope from 10 degrees to 30 degrees . It was found that the physiological cost of stairs is always less than a ramp of equal slope and that stairs with a 6 in riser were usually better than those with a 4 in riser. The values of the flexion at the knee joint were compared with a theoretical analysis by Shinno and found to differ considerably.

Shielding factory noise by work-in-progress storage

Studies in several open machine shops equipped with large numbers of noisy machines suggest that although any one machine may not be excessively noisy, the combination of many in a reverberating environment causes a ‘standing peak’ of noise at an unacceptable level. Suitably placed barriers with slight attenuating properties may thus be enough to reduce the high noise peaks to tolerable limits. Case studies showing the effects of stacks of work-in-progress on noise levels are described in this article and an indication is given of how computer simulation can be used to decide on the layout of a factory incorporating such noise barriers.

The ergonomics of open-fronted C-frame presses.

This study comprised three phases: an industrial survey of press design and operation; a shopfloor evaluation of performance with a modified press and its comparison with the original design; and a laboratory simulation of the effects of three of the most pertinent ergonomics design factors. The survey showed that many features of press design were in disagreement with ergonomics criteria, often markedly so, and that these presented potentially important limitations to performance. The modified press layout produced evidence of superior performance in comparison with the original layout and this was substantiated by the simulation particularly in terms of the reach required to the die.

Tower cranes survey 2: A decade of non-progress?

Ten years ago the authors carried out a survey on tower cranes in the Birmingham area, and recommended a number of improvements to control layout, warning devices, cabin design and operator training. A later survey enables a comparison to be made, with a review of the application in the intervening decade of the earlier recommendations.

The ergonomics of vertical turret lathe operation

A study of the work load of 14 vertical turret lathe operators engaged on different work tasks in two factories is reported. For eight of these workers continuous heart rate recordings were made throughout the day. It was shown that in four cases improved technology was unlikely to lead to higher output and certain aspects of posture and equipment manipulation were major contributors to the limitations on increased output. The role of the work-rest schedule in increasing work loads was also demonstrated. Improvements in technology and methods to reduce the extent of certain work loads to enable heavy work to be done in shorter periods followed by light work or rest periods are given as means to modify and improve the output of these machines. Finally, the direction for the development of a predictive model for man-machine matching is introduced.

Industrial ergonomics at Birmingham

The Industrial Ergonomics group at the University of Birmingham have the benefit of working with technologists, operational researchers, accountants and management specialists in the inter-disciplinary Department of Engineering Production. The unique opportunities provided by this mixture have been utilised to develop an approach to industrial problems and professional training infused by more than ergonomics expertise. Some of the activities in teaching and research of this group are described below.