PRINCIPLES OP MACHINES 



471 



6') Rope transmission: Rope 



(Fig. 360) has been used to a 

 limited extent for transmitting 

 power long distances and where 

 the shafting is not parallel. 

 The rope can be changed in any 

 direction by means of an idler. 

 The sheaves (pulleys) over 

 which the rope runs should be 

 grooved to grip the rope. Some 

 method of tightening must be 

 employed, as the length of the PlG 'J 

 rope is variable. Where the 



Afic-r International Harvester Go. 



Link ifi'lt and sprocket 



wheel 



drive is exposed to the 

 weather a wire cable is 

 used in place of a rope, 

 but in this case the sheaves 

 should not grip the cable. 

 Cog gearing. Cog gear- 

 ing is used for a positive 

 transmission of power with 

 a minimum of slack mo- 

 tion. The teeth are care- 

 fully designed and cut for 

 rolling contact between 

 tooth surfaces. When the two shafts are parallel, the teeth 

 are placed on the rim and the gears are called spur gears 



After [ntemational Harvester Co. 



Fig. 360. A rope belt 



Fig. 361. Spur gearing 



After I,ink Mult Co. 



(Fig. 361). When the shafts are at an angle and in the same 

 plane, they are bevel gears (Fig. 362). Spiral and worm gears 



