l66 FARM MACHINERY 



the shafting are cored out, but where the bearings are to 

 be located enough extra material is provided for boring 

 out to size. Roller bearings are usually provided for the 

 main axle. 



231. The crank shaft is usually provided with a plain 

 bearing at the crank and a roller bearing at the pinion 

 end. A ball bearing is provided at the end of the small 

 bevel pinion to take the end thrust. It is not possible to 

 use a ball or roller bearing at the crank end, due to the 

 vibratory action of the shaft tending to wear the bearing 

 out of round. This bearing is either provided with an 

 adjustment or an interchangeable brass bushing to take 

 up the wear. The crank should be well protected from 

 the front and under sides. The crank and pitman motion 

 seems to be the most satisfactory device to transmit a 

 reciprocating motion to the knife. A wobble gear was 

 tried a few years ago, but has been given up. A mower 

 is manufactured with a pitman taking the motion from 

 the face of the crank wheel instead of the side. It is not 

 known how successful this machine is. 



232. Main gears. The driving gears should be liberal 

 in size and always closed in such a way as to be protected 

 from dust, and also to facilitate oiling. It might be an 

 advantage in mowers as in some other machines to have 

 the gears run in oil. 



233. Wheels should be high and have a good width of 

 tire. The common height is 32 inches, and 3^ and 4 

 inches the common width of tire. It is some advantage to 

 have several pawls to engage the ratchet teeth in the 

 wheels, because this feature, in connection with a clutch 

 with several teeth for throwing the machine in and out of 

 gear, will make the machine more positive in its action. 

 That is, the sickle will start to move very shortly after 

 the main wheels are set in motion. Mowers driven by 



