



piston has such a quick taper is that the piston has to be taken off 

 themdwl.. the cylinder. The cross-bead being for*ed on 



the end of the piston rod prevents the piston and piston rod being 



<4. Pistons of large diameter are generally 

 I uith two cast-iron packing rings placed within the 

 groove. These rings are pressed outwards against the 

 r Under, and also against the sides of the groove by one or 

 1 >ne form of this packing (Lancaster's) is shown 

 i fig. 59. Here one spring only is used, and it is first 





FlO, f . 



a strni .-I thm I -nt round and its ends united. 



The a w r will be clearly uiultTKtiMMl from the 



illustr purpose of admitting the packing rings 



the piston i* di\i-l-.l into two parts, one the piston proper, 



iiiul tin- otli.r tin- junk thr junk ring, 



ii is secured to the piston by means of bolts as shown. 



> GO: .Minn* Emginr /'M/.HI. -The piston Ulnstrated by 

 fig. 59 is for tli.- 1 1 n;h -pressure cylinder of a marine engine. The 

 piston, junk ring, and packing rings are of cast puton rod 



it are of wrought iron, so also are the junk rink* bolts. The 

 nuts for the Utter are of brass. The spiral spring is made from 

 diameter. An enlarged section of one of the pack- 



