166 



PANEL DESIGN 



opposite directions (1). In several investi- 

 gations, it has been found that redesigning 

 work-layouts to permit these types of move- 

 ments has had significant results in increas- 

 ing the efficiency of operation and the output 

 of workers. For example (27) in a simple 

 soldering operation, output was nearly 

 doubled when as many of these principles of 

 movement as possible were incorporated into 

 the rearrangement of the items used in the 

 operation (Fig. 9). Similar advantages 

 could probably be gained by arranging the 

 panels of military equipment to allow more 



stick or a wheel control, subjects were able 

 to stay on a target much more of the time 

 than they could by using rudder controls. 

 More studies of this sort are needed, com- 

 paring the hands and feet in other miUtary 

 operations, for industrial investigations have 

 sho%vn that in many types of work, rather 

 dehcate operations can be performed with 

 foot pedals and knee levers (1, 2). When 

 the hands and arms alone are considered, 

 it turns out that in some current equip- 

 ment, the right hand is greatly overloaded 

 while the left remains idle a great deal of the 



-Flux Pot 



Supply Pan Supply Pan 



B. New Method 



A. Original Method 



Fig. 9. Redesign of a work layout to permit the most efficient patterns of movements. (From Mo- 

 genson, 27) 



efficient movements in the operation of con- 

 trols. Only direct experimental test will 

 tell. 



Distribution of Work over 

 the Body Parts 



Part of the same problem of arrangement 

 of controls and displays is the question of 

 overloading parts of the body with work. 

 In general, it is said that there should be 

 equitable distribution of work for all parts 

 of the body. As far as controls are con- 

 cerned, it has been pointed out that the 

 hands are usually overloaded, and that wher- 

 ever possible, the feet should take over the 

 operation of controls. There are some 

 obvious limitations on what the feet can do. 

 One study has shown that the feet and legs 

 are distinctly inferior to the hands and arms 

 in pursuit tasks (17). Operating either a 



time (2, 7). Wherever possible, this type 

 of situation should be rectified by relocation 

 of controls so that they are more symmet- 

 rically distributed about the midUne of the 

 operator's body. 



Classification of Movements 



In keeping with a principle of least effort, 

 it has been recommended in many industrial 

 studies that the operation of controls be 

 assigned to the lowest classification of body 

 movements (1, 2). Finger motions are con- 

 sidered the easiest to make and hence given 

 the lowest classifications; wrist, forearm, up- 

 per arm, and shoulder movements are con- 

 sidered more difficult in that order. This 

 classification principle imphes that up to a 

 certain point at least, the more controls 

 that can be operated by the fingers, the less 

 the fatigue, and the greater the efficiency of 



