Pttteti Sedt 



Popular Science Monthy 



if the work is properly carried on but if- 

 for any reason the piston should be 

 pushed too far up into the cylinder on 

 some types of engines the top ring will 

 expand into the combustion chamber and 

 will lock the pistons tightly in place. 

 This is a difficult condition to overcome 

 with some forms of cylinders though if 

 the cylinder casting is of the L or T form 

 it may be possible to compress the rings 

 sufficiently to remove the piston by sim- 

 ple means. The best method is shown 

 at Fig. 13, A. A very thin strip of 

 metal of approximately the same width 

 as the piston rings is passed through one 

 of the valve chamber openings and 

 passed around the pis- 

 ton and pulled out 

 through the other 

 opening. It requires 

 the services of two 

 people and sometimes 

 three to remove a pis- 

 ton stuck in this man- 

 ner. The efforts of 

 one are directed to 

 keep the band taut un- 

 der the ring and to 

 exert an upward pull 

 which forces that por- 

 tion of the ring em- 

 braced by the metal 

 band to fill the groove 

 in the piston. Another 

 person uses a pair of 

 screw drivers, one 

 through each valve chamber opening to 

 compress the ring at the points indi- 

 cated in the drawing. This means that 

 a three-point compressional effect is ob- 

 tained and it is a simple matter for 

 the third person to draw the piston back 

 into the cylinder when the ring has been 

 properly compressed in its groove. It is 

 not always possible to compress the ring 

 so the only other alternative is to break 

 it in a number of pieces by hitting the 

 brittle ring with a drift or chisel and 

 then withdrawing the pieces one at a 

 time until the ring has been entirely re- 

 moved. With the T-head cylinder it is 

 sometimes possible to remove the ring 

 without the use of the metal bands, as 

 that member is compressed at diamet- 

 rically opposite points by a screw driver 



133 



inserted through each valve chamber 

 cap. 



Fitting Piston Rings 

 Before installing new rings, they 

 should be carefully fitted to the grooves 

 to which they are applied. The tools 

 required are a large piece of fine emery 

 cloth, a thin, flat file, a small vise with 

 copper or leaden jaw clips, and a smooth 

 hard surface such as that afforded by 

 the top of a surface plate or a well- 

 planed piece of hard wood. After mak- 

 ing sure that all deposits of burnt oil 

 and carbon have been removed from the 

 piston grooves, three rings are selected, 

 one for each groove. The ring is turned 



Fig. II. Forms of valve grinding tools and methods 

 of grinding 



all around its circumference into the 

 groove it is to fit, which can be done 

 without springing it over the piston as 

 the outside edge of the ring may be used 

 to test the width of the groove just as 

 well as the inside edge. The ring should 

 be a fair fit and while free to move cir- 

 cumferentially there should be no ap- 

 preciable up and down motion. 



The ring should be pushed into the cyl- 

 inder at least two inches up from the 

 bottom and endeavor should be made to 

 have the lower edge of the ring parallel 

 with the bottom of the cylinder. If the 

 ring is not of correct diameter, but is 

 sliglitly larger than the cylinder bore, this 

 condition will be evident by the angular 

 slots of the rings being out of line or by 

 difficulty in inserting the ring if it is a 



