398 FARM MOTORS 



handholes, where there is no motion. Such packing 

 should be just thick enough to cover the uneven surfaces 

 and no more. 



548. Pounding. An engine which pounds is generally 

 loose or worn, and if permitted to continue pounding will 

 gradually become worse. The wrist and crank bearings 

 are those most likely to pound. Nevertheless, there are 

 so many other places where the engine will pound that 

 it is well to look not only at these points, but at others. 

 An experienced engineer will have no trouble in de- 

 tecting the exact place, but a new man should work 

 cautiously. He should block the crosshead, and then 

 turn the flywheel backward and forward an inch or two. 

 This will tell whether the pound is in the flywheel, main 

 bearings, crank pin or wrist pin. This will not tell, how- 

 ever, if the pound is in the governor belt pulley, or 

 guides. A new engineer should not try to take out all 

 of the pound at once ; only take up the slack a trifle at a 

 time until it is all removed. It is better to run a box too 

 loose and have it pound than too tight and have it cut. 

 An engine may also be loose in the eccentric and valve, 

 and cause pounding, or sometimes it will pound when out 

 of line. In the former case a little tightening will remove 

 the pound ; not too much, however, or the eccentric may 

 cut or the valve bind. If the engineer thinks the shaft 

 is out of line, he can detect it by taking the front half of 

 the crank bearing off the connecting rod, and then by in- 

 spection see if the connecting rod freely rests in its posi- 

 tion in the crank pin in all parts of the stroke of the 

 piston. 



549. Bearings. All important boxes and those which 

 are likely to wear should be made in halves with liners 

 between the halves. This permits of taking up the wear, 

 without requiring a new bearing. T]he ideal bearing is 



