210 HANDBOOK OF MECHANICAL DESIGN 



This equation can be used only where the linear speed bears a continuous fixed 

 relation to the rotating speed, as a rack driven by a gear. A more complex equation 

 is necessary for systems involving reciprocating hnear motion obtained by a crank 

 arm. 



By this method, it is possible to reduce the WR^ of the individual parts of a com- 

 plex system to an equivalent WR- at the drive or motor shaft speed. These values of 

 equivalent WR^ may be added directly, and the total equivalent WR^ plus the WR^ of 

 the driving unit or the motor represents the WR^ of the complete system which the 

 motor must accelerate or decelerate. All further calculations may be made as though 

 the system were a simple one of one element of WR' equal to the total equivalent WR-. 



To simplify the calculation of the radius of gyration of various mechanical struc- 

 tures, see the tables on pages 17 and 19 to 25. 



