Question about old piston rings

[tom'sB2B]

Anyone know what the hexagonal shaped ring is for? Is it an expander for the oil rings?

[Sniper]

The only references I can find to an expander ring is for two stroke engines and they were used behind the second compression ring, but two strokes have no oil control rings either.

 

http://yamaha-ls3.blogspot.com/2016/01/new-piston-with-keystone-rings.html

 

https://nsr-world.com/workshop/rebuild/html/workshop-content-rebuild-4.htm

[JBNeal]

This may or may not help...

[dpollo]

The expander, called a Marcel is most often found behind the upper oil ring.  In some ring sets, a marcel is used behind the second compression ring