Tangent to the Rod Wiper Rings. Available in Iron, Bronze, or Babbit (as shown)
This type 313 oil wiper ring is used in reciprocating compressors to prevent oil from the crankcase traveling along the piston rod with no clearance at the bore. Each ring is an independent seal with a deep wiping edge and wide oil groove at the I.D. The oil groove acts as a second wiping edge and uses drilled holes to allow the wiped oil to drain away from the rod. This wiper ring has a tapered wiping edge on the face of the ring to more effectively strip the oil coating from the piston rod.

The function of the cast iron oil wipers is to simply scrape oil from the piston rod on the outward stroke. This prevents sump oil from entering the distance piece by allowing it to return to the crankcase through a drain hole in the bottom of the wiper cup.