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end on one side, this permitting the 

 lower portion to swing down the crank 

 pin to pass out from between the halves 

 when the retaining bolt is removed. In 

 the marine type, which is the most com- 

 mon, one or two bolts are employed at 

 each side and the cap must be removed 

 entirely before the bearing can be taken 

 off of the crank pin. The tightness of 

 the brasses around the crank pin can 

 never be determined solely by the ad- 

 justment of the bolts, as while it is im- 

 portant that these should be drawn up 

 as tightly as possible the bearing should 

 fit the shaft without undue binding, even 

 if the brasses must be scraped to insure 

 a proper fit. As is true of the main 

 bearings, the marine form of connecting 

 rod has a number of liners or shims in- 

 terposed between the top and lower por- 

 tions of the rod end and these may be 

 reduced in number when necessary to 

 bring the brasses closer together. 



In fitting new brasses there are two 

 conditions to be avoided, these being out- 

 lined at Fig. i6, C and D. In the case 

 shown at C the Hght edges of the brush- 

 ings are in contact, but the connecting 

 rod and its cap do not meet. When the 

 retaining nuts are tightened the entire 

 strain is taken on the comparatively 

 small area of the edges of the bushings 

 which are not strong enough to with- 

 stand the strains existing and which 

 flatten out quickly, permitting the bear- 

 ing to run loose. In the example out- 

 lined at D the edges of the brasses do 

 not touch when the connecting rod cap 

 is drawn in place. This is not good 

 practice, because the brasses soon be- 

 come loose in their retaining member. 

 In the case outlined it is necessary to 

 file off the faces of the rod and cap until 

 these meet, and to insure contact of the 

 edges of the brasses as well. In event 

 of the brasses coming together before 

 the cap and rod make contact, as shown 

 at C, the bearing halves should be re- 

 duced at the edges until both the caps 

 and brasses meet against the surfaces of 

 the liners as shown at A. 



Before assembling on the shaft, it is 

 necessary to fit the bearings by scrap- 

 ing, the same instructions given for re- 

 storing the contour of the main bear- 

 ings applying just as well in this case. 

 It is apparent that if the crank pins are 



Popular Science Monthly 



not round no amount of scraping will 

 insure a true bearing. A point to ob- 

 serve is to make sure that the heads of 

 the bolts are imbedded solidly in their 

 proper position and that they are not 

 raised by any burrs or particles of dirt 

 under the head which will flatten out 

 after the engine has been run for a time 

 and allow the bolts to slack off. Simi- 

 larly, care should be taken that there 

 is no foreign matter under the brasses 

 and the box in which they seat. To 

 guard against this the bolts should be 

 struck wuth a hammer several times 

 after they are tightened up, and the con- 

 necting rod can be hit sharply several 

 times under the cap with a wooden 

 mallet or lead hammer. It is important 

 to pin the brasses in place to prevent 

 movement, as lubrication may be inter- 

 fered with if the bushing turns round 

 and breaks the correct register between 

 the oil hole in the cap and brasses. 



Care should be taken in screwing on 

 the retaining nuts to insure that they 

 will remain in place and not slack off. 

 Spring washers should not be used on 

 either connecting rod ends or main bear- 

 ing bolts, because these sometimes snap 

 in two pieces and leave the nut slack. 

 The best method of locking is to use 

 well-fitting split pins and castellated 

 nuts. In a number of the cheaper cars, 

 the bearing metal is cast in place in the 

 connecting rod lower end and in main 

 bearings, and is not in the form of re- 

 movable die cast bushings. 



Precautions in Reassembling Parts 

 When all of the essential components of 

 a power plant have been carefully 

 looked over and cleaned and all defects 

 eliminated, either by adjustment or re- 

 placement of w^orn portions, the motor 

 should be reassembled, taking care to 

 have the parts occupy just the same 

 relative positions they did before the 

 motor was dismantled. 



Before the cylinders are replaced on 

 the engine base, heavy brown paper gas- 

 kets should be made to place between 

 the cylinder base flange and top portion 

 of the engine crank case. Gaskets will 

 hold better if coated with shellac, as it 

 fills irreg-ularities in the joint and assists 

 materially in preventing leakage after 

 the coating has a chance to set. 



