Figure 35. — Detail of links in the Roux system. 

 (From Gustave Eiffel, La Tour de Trois Cents 

 Metres, Paris, 1900, p. 156.) 



rollers, working within the hollow guides. Corre- 

 sponding helical ribs in the guides rotated the rollers 

 as the car moved. If the car speed exceeded a set 



it 



© • ^. ^Q Q/ 



4^ m^^^ qq©©oJjIq^ 



Figure 36. — Section of guide trunks in the Roux 

 system. (From Gustave Eiffel, La Tour de 

 Trois Cents Metres, Paris, 1900, p. 156.) 



limit, the increased resistance offered by the apparatus 

 drove the rollers up into friction cups, slowing or 

 stopping the car. 



The device was considered ineffectual by Edoux 

 and Eiffel, who were aware that the ultimate safety 

 of the system resulted from the use of supporting cables 

 far heavier than necessary. There were four such 

 cables, with a total sectional area of 1 5.5 square inches. 

 The total maximum load to which the cables might 

 be subjected was about 47,000 pounds, producing 

 a stress of about 3,000 pounds per square inch com- 

 pared to a breaking stress of 140,000 pounds per square 

 inch — a safety factor of 46 ! ^^ 



If' M. A. Ansaloni, "The Lifts in the Eiffel Tower," quoted 

 in Engineering, July 5, 1889, vol. 48, p. 23. The strength of 

 steel when drawn into wire is increased tremendously. Break- 

 ing stresses of 140,000 p.s.i. were not particularly high at the 

 time. Special cables with breaking stresses of up to 370,000 

 p.s.i. were available. 



36 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



