Fig. 12. A nail 



or piece of wire 



will grind Buick 



valves 



134 



lap joint form. 

 If such is the 

 case the ring is 

 removed from the 

 cylinder and 

 placed in the vise 

 between the soft 

 metal jaw clips, 

 as shown at Fig. 

 13 B. Sufficient 

 metal is removed 

 with a fine file 

 from the edges 

 of the ring at the 

 slot until the 

 edges come into 

 line and a slight 

 space exists between them when the ring 

 is placed into the cylinder. It is impor- 

 tant that this space be left between the 

 ends, for if this is not done, when the 

 ring becomes heated the expansion of 

 metal may cause the ends to abut and 

 the ring to jam in the cylinder. 



Another method of fitting a piston ring 

 is indicated at Fig. 13, C. A plug is 

 made of soft wood, such as yellow pine 

 that will be an easy fit in the cylinder and 

 one end is turned down enough so that 

 a shoulder will be formed to back the 

 ring. The turned down por- 

 tion should be a little less than 

 the width of the ring to be 

 tested. The ring is pushed on 

 this turned down end of the 

 wooden plug and held by a 

 small batten secured by a 

 screw in the center. This does 

 not hold the ring tightly 

 enough to keep it from closing 

 up. It is also important to 

 turn the end of the wooden 

 plug small enough so that its 

 diameter will be less than the 

 bore of the ring when that 

 member is tightly closed. The 

 cylinder bore is smeared with 

 a little Prussian blue pigment 

 which is spread evenly over the cylin- 

 der wall with a piece of' waste and the 

 ring is moved back and forth in the 

 cylinder while it is held square by the 

 shoulder on the plug. The high spot 

 on the ring will be shown by color. Us- 

 ually the ring will be found to bear hard- 

 est at each side of the slot. These high 

 spots are removed carefully with a very 



Popular Science Monthly 



fine mill file or piece of emery cloth and 

 the ring is again inserted, in the cylinder 

 bore to find other high spots which are 

 removed in a similar manner. When the 

 rings fit fairly well all around, the en- 

 tire surface will have a uniform coating 

 of blue. 



If the old piston rings are bright all 

 around but appear to have lost their elas- 

 ticity, a new lease of life may be given 

 by a process known as peening, which is 

 shown at Fig. 13, D. The ring is stood 

 on a surface plate and is tapped inside 

 with the peen end of a light hammer us- 

 ing the harder blows at the thick section 

 and gradually reducing the force of the 

 blow as the slot is approached. If skill- 

 fully done a ring may be stretched to 

 some extent and considerable elasticity 

 imparted. Piston rings are not always 

 of simple form shown. Various duplex 

 constructions have been offered with an 

 idea of reducing the possibility of leak- 

 age. A ring of this type which is known 

 as the "Leak Proof" piston packing is 

 shown at Fig. 13, E. These duplex rings 

 are harder to install than the simple 

 forms, and it is important that they be 

 carefully fitted to the cylinder and to the 



f,7e 



Wood Block 



LeahProof Pkton Ring 



Fig. 13. Processes incidental to piston ring 

 restoration 



piston grooves, as described below. 



The bottom ring should be placed in 

 position first; this is easily accom- 

 plished by springing the ring open 

 enough to pass on the piston and then 

 sliding it into place in the lower groove 

 which on some types of engines is below 

 the wrist pin, whereas in others all 

 grooves are above that member. It is 



