Figure 25. — Schematic diagram of the rigging 

 of the Otis system. (Adapted from Gustave 

 Eiffel, La Tour de Trois Cents Metres, Paris, 

 1900, p. 127.) 



apparatus was really not unlike that of an ordinary in- 

 clined railway. Motive power was provided by the 

 customary hydraulic cylinder (fig. 26), set on an angle 

 roughly equal to the incline of the lower section of run. 

 Balancing the cabin's dead weight was a counterpoise 

 carriage (fig. 27) loaded with pig iron that traveled on 

 a second set of rails beneath the main track. Like the 

 driving system, the counterweight was rope-geared, 

 3 to 1, so that its travel was about 125 feet to the 

 cabin's 377 feet. 



Everything about the system was on a scale far 

 heavier than found in the normal elevator of the 

 type. The cylinder, of 38-inch bore, was 36 feet long. 

 Rather than a simple nest of pulleys, the piston rods 

 pulled a large guided carriage or "chariot" bearing 

 six movable sheaves (fig. 28). Corresponding were 

 five stationary sheaves, the whole reeved to form an 

 immense 12-purchase tackle. The car, attached to the 

 free ends of the cables, was hauled up as the piston 

 drew the two sheave assemblies apart. 



In examining the system, it is difficult to determine 

 what single element in its design might have caused 

 such a problem as to have been beyond the engineer- 

 ing ability of a French firm, and to have caused such 

 concern to a large, well-established American organ- 

 ization of Otis' wide elevator and inclined railway- 

 experience. Indeed, when the French system — 



which served the first platform from the east and 

 west legs — is examined, it appears curious that a 

 national technology capable of producing a machine 

 at such a level of complexity should have been 

 unable to deal easily with the entire matter. This can 

 be plausibly explained only on the basis of Europe's 

 previously mentioned lack of experience with rope- 

 geared and other cable-hung elevator systems. The 

 difficulty attending Otis' work, usually true in the 

 case of all innovations, lay unquestionably in the 

 multitudes of details — many of them, of course, 

 invisible when only the successfully working end 

 product is observed. 



More than a matter of detail was the Commission's 

 demand for perfect safety, which precipitated a situa- 

 tion typical of many confronting Otis during the 

 entire work. Otis had wished to coordinate the 

 entire design process through Mr. Hall, with technical 

 matters handled by mail. Nevertheless, at Eiffel's 

 insistence, and with some inconvenience, in 1888 the 

 company dispatched the project's engineer, Thomas E. 

 Brown, Jr., to Paris for a direct consultation. Mild 

 conflict over minor details ensued, but a gross differ- 

 ence of opinion arose ultimately between the American 

 and French engineers over the safety of the system. 

 The disagreement threatened to halt the entire project. 

 In common with all elevators in which the car hangs 

 by cables, the prime consideration here was a means 

 of arresting the cabin should the cables fail. As 

 originally presented to Eiffel, the plans indicated an 

 elaborate modification of the standard Otis safety 

 device — itself a direct derivativeof E.G. Otis' original. 



If any one of the six hoisting cables broke or 

 stretched unduly, or if their tension slackened for any 

 reason, powerful leaf springs were released causing 

 brake shoes to grip the rails. The essential feature of 

 the design was the car's arrest by friction between 

 its grippers and the rails so that the stopping action 

 was gradual, not sudden as in the elevator safety. 

 During proof trials of the safety, made prior to the 

 fair's opening by cutting away a set of temporary 

 hoisting cables, the cabin would fall about 10 feet 

 before being halted. 



Although highly efficient and of imquestionable 

 security, this safety device was considered an insuffi- 

 cient safeguard by Eiffel, who, speaking in the name 

 of the Commission, demanded the application of a 

 device known as the rack and pinion safety that was 

 used to some extent on European cog railways. The 

 commissioners not only considered this system more 

 reliable but felt that one of its features was a necessity: 



PAPER 19: ELEVATOR SYSTEMS OF THE EIFFEL TOWER 



25 



