16 



INFLUENCE DIAGRAMS 



with the horizontal projection of VL" as the length of the 

 cut stringer. The values of x f and d f can now be found 

 in the usual manner from the truss diagram. 



1 j> ^--d-^ 



FIG. 8. 



The criterion for the position of wheel loads producing 

 maximum moment is found in the manner previously ex- 

 plained. Referring to equation (13) and Fig. 8. 



- = ^ 2 ( tan 3 +tan 2 ) TF 2 '(tan 3 tan 2 ) 



-TF 3 tan 3 =0, (42) 



or 



tan 3 = 



') tan 2 . . (43) 



Substituting the values of the tangents 



.... (44) 



