PRIN. OF INTERNAL COMBUSTION ENGINES - OD1619 LESSON 1/TASK 1
FIGURE 23. STAGGERING RING GAPS.
(5) Second Compression Ring (figure 23). The primary reason for using a second
compression ring is to hold back any blowby that may have occurred at the top ring.
A significant amount of the total blowby at the top ring will be from the ring gap.
For this reason, the top and the second compression rings are assembled on the
piston with their gaps 60 offset.
(6) Oil Control Rings (figure 24 on the following page). The oil control rings
serve to control the lubrication of the cylinder walls. They do this by scraping
the excess oil from the cylinder walls on the downstroke. The oil is then forced
through slots in the piston ring and the piston ring groove draining back into the
crankcase. The rings are made in many different configurations, from onepiece
units to multipiece assemblies. Regardless of the configuration, all oil control
rings work basically in the same way.