Alfalfa in Kansas. 307 



gears should be of ample size to withstand the strain. Warped gears 

 are to be looked out for, as they wear and give trouble more quickly and 

 the noise they make is annoying. Steel-cut gears would be a good thing 

 in a mower, but the first cost seems to be too great. The small pinion 

 on the pitman shaft usually wears out first, so means are usually pro- 

 vided so that it can be kept in mesh. ' Ball bearings or hardened steel 

 washers are used to take up end thrust due to the bevel gears. 



Chain drives on mowers do not give as good service as gears, for they 

 wear out more quickly and have more play. 



Nearly all standard makes of mowers have the principal wearing 

 parts replaceable. The majority of them have brass bronze composition- 

 metal bushings at both ends of the pitman shaft. If the bearings become 

 worn or loose it is only necessary to replace the bushing with a new one. 



The wrist-pin bearings are generally made solid, as it is hard to keep 

 the nuts tight on a split box at this place on account of the vibration. 

 Removable bushings are usually provided, and in most machines these 

 bushings are free to turn. 



The most common method of securing the pitman to the sickle head 

 is by a ball-and-socket joint. This form of connection seems to be the 

 most convenient and the easiest to keep tight. This bearing should not 

 be kept too tight, as it not only increases friction, but causes the sickle back 

 to bend up and down at each stroke of the sickle, and is apt to cause 

 it to break off. Neither should it be left loose enough to have much 

 play, or the socket will soon be beaten into an oblong shape; then the 

 bearing can not be kept tight until the damaged parts are replaced by 

 new ones. 



CARE OF THE MOWER. Heavy draft in a mower is caused by three 

 things poor lubrication, dull sickles, and nonalignment. The remedy 

 for the two former is obvious, but the latter is often overlooked. The 

 pitman and sickle should work in a straight line. If the outer end of 

 the cutter bar has dropped back, part of the power is taken up by friction 

 on the mower. All cutter bars need an occasional realignment; that is, 

 the wrist pin, sickle head, and outer end of the sickle should be brought 

 into a straight line. This may be accomplished by having one of the 

 hinge pins in the shoe set in an eccentric cam, and by changing the posi- 

 tion of the hinge bar and the pitman head ; ot it may be done to a limited 

 amount by shortening the drag bar and lengthening the push bar. The 

 common notion that the cutter bar can be aligned by shortening the drag 

 bar or lengthening the push bar alone is erroneous and should be dis- 

 carded, as the shortening of the drag bar affects the centering of the 

 sickle. If there is no other provision for aligning the bar a new shoe 

 or hinge pin should be purchased. However, a more or less skilled me- 

 chanic or careful workman may align the cutter bar by removing one 

 of the hinge pins and bringing the outer end of the bar up in position 

 and filing one side of the hole out with a round file until the pin can be 

 replaced and bushed up on the loose side of the pin. The bushing should 

 be notched to keep it in place. 



CENTERING THE SICKLE. If a new pitman is to be replaced, great care 

 should be taken to get the new one the same length as the old, in order 



