THE MODERN SKYSCRAPER 



SAFETY DEVICES 



But after all, the various mechanisms for moving 

 the elevator up and down are of minor importance 

 from the passenger's point of view, when compared 

 with the device for stopping the elevator in case of a 

 breakage of the lifting apparatus. This was pointed 

 out more than half a century ago by the first inventor 

 of such a device and is just as true to-day. 



An elevator is really a railroad with a grade of ninety 

 degrees, but differing from the ordinary railroad in 

 that the car slides along two rails instead of pass- 

 ing over them on wheels. The rails of the elevator, 

 then, act only as guides for keeping the car in position 

 except in case of accident, when they play an all-im- 

 portant part in stopping the descent of the car. Many 

 such devices have been invented, but practically all 

 of these fall into one of two classes those designed 

 to act upon wooden rails, and those that act upon metal. 

 The safety devices which act upon wooden rails do so 

 by gouging into the wood, and may be in the form of 

 safety dogs, or chisel-like structures; while those that 

 act upon metal rails are usually in the form of nippers 

 that grip the rail on either side. Some of these are 

 controlled by the action of springs which allow the 

 safety device to act only when the car is moving 

 faster than a certain rate of speed in short when it 

 is actually falling. 



This type is used mostly on small elevators and is 

 considered inferior to those that are controlled by some 



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