Str^m-Tejsen and Chislett 



Fig. 8 - The HyA planar-motion 

 mechanism mounted on the tow- 

 ing carriage during testing 



Both worm-and-wheel reduction gearbox and belt drive are designed and 

 manufactured to allow a chatter -free and vibration-free angular motion even 

 under the most rapidly changing load conditions. Current is supplied to the 

 motor by a Ward Leonard system installed on the carriage, enabling revolutions 

 to be continuously varied from 2 to 40 rpm. By these means a predetermined 

 revolution value can be maintained within fine limits, independent of loading. 



The uniform rotary motion of the main shaft is converted to periodic trans- 

 latory motion in the horizontal plane by a scotch yoke attached to each end (Fig. 

 9). The amplitudes of the scotch yokes can be continuously varied from to 100 

 mm, and the settings are indicated with an accuracy of 0.1 mm by small built-in 

 mechanical digital counters. No appreciable wear has occurred in the brass-to- 

 steel block and slider systems after several hundred hours of operation. 



330 



