HORSE-POWERS. Ill 



speed of about 227 revolutions per minute. The required 

 speed of the tumbling-rods is found, in each case, by multi- 

 plying the number of revolutions of the cylinder by the num- 

 ber of teeth on the cylinder-pinion and dividing the product 

 by the number of teeth on the bevel-gear. 



Jacks for Horse-Powers. The device used to change the 

 motion of the tumbling-rods into that of a pulley is called 

 a "jack." The "Case" jack has a bevel-gear, (2o8T), with 

 sixty teeth and a pinion, (2O9T), with twenty-two teeth. 

 The pulley, (2o6T), is sixteen inches in diameter and has 

 a six-inch face. 



Adjusting the Iron-Frame Horse-Power. It is very im- 

 portant that the bull-pinions should mesh properly with the 

 bull-wheel. When the bull-pinion shafts are correctly set, 

 the bull-wheel will not have more than one-sixteenth of an 

 inch up and down play at any point. As the web between 

 the upper and lower cogs of the bull-wheel varies in thick- 

 ness, it is best to locate the thickest place and mark it. 

 This part may be then turned between the bull-pinions and 

 the shaft bearings adjusted so that the gears mesh as deeply 

 as possible and at the same time allow the bull-wheel to pass 

 freely between them. In building powers at the factory 

 leather packing is placed between the box of the upper 

 short bull-pinion shaft and the main frame It is the inten- 

 tion to shave down this leather packing from time to time 

 as the bearings wear, thus allowing the bull-pinions to be 

 kept in proper mesh by means of set screws. The box of the 



