406 FARM MOTORS 



end of the cylinder, then start it up. This action tends 

 to produce a vacuum in the crank case, but instead of 

 doing so the charge rushes in through the check valve A 

 (Fig. 285) and fills the space. Now start the piston 

 down again, compressing the charge in the crank case 

 (Fig. 286) until the piston has opened the inlet port, 

 when the charge rushes from that end of the cylinder up 



FIG. 285 



FIG. 286 



into the other. As the piston starts back again (Fig. 287) 

 it closes the openings and compresses the charge now in 

 the head end. At the same time it is doing this a new 

 charge is being drawn into the crank case. When the 

 piston reaches the upper end of the stroke explosion takes 

 place and the expansion forces the piston down (Fig. 288), 

 compressing the charge in the crank case and expanding 

 the one in the cylinder. When the piston has passed the 



