Rings & Riders

Compressor Piston RingsRider Rings & Rider Bands

CompressorPiston Rings

Piston RingOne Piece But CutOne Piece Angle CutTwo Piece Angle CutThree Piece Step CutCHECKING END GAPBe sure to position rings inthe cylinder boreGeneral RuleBUTT CUT RINGS(Teflon).0195 per inch of bore diameter(PEEK).0064 per inch of bore diameterTolerance = +.020/-.000Angled Cut RingsButt Cut x .707 + TolerancePistonCylinder boreCounterborePiston with conventional rings Seal Seal= gas pressurePiston movementPistonCylinder boreCounterborePiston with combination rings Seal SealPiston weight makes bottom half of the ringseal against cylinder bore.= gas pressurePiston movementMetallic piston ring materialsCAST IRON*Dirty or corrosive gasesBRONZE*High pressure*High temperatureNon-metallic piston ring materialsPTFE TEFLONCarbon filled - Non-lube and lubricatedGlass and Moly filled LubricatedBronze filled - Non-lube and lubricated (mostly air service) High temperature, non-corrosiveRytonTHERMOPLASTICS - (Lubricated)Combination rings Compressor Piston RingsAny Questions?

Rider Rings&Rider Bands

Rider Ring / BandUsing rider rings or rider bandsto support the piston off of the boreRider BandRider RingGeneral RuleSide Clearance = .012 per inch of ring width General RuleRider End GapNormally twice thatof the piston ring gap.

RAMGap & Side ClearanceRecommendationsTypical application for rider ringsTypical application for rider bands120oEffective length of rider = .866 x cylinder diameterSizing rider rings / bandsDetermining rider thicknessBore diameter Rider thickness

up to 12.25012 to 16.31216 to 21.37521 to 26.43826 and larger.500Sizing rider rings / bandsDetermining rider O.D.Rider O.D. = Bore size - running clearanceRunning clearance:Cast iron = .002 per inch bore dia.Aluminum = .003 per inch bore dia.

Ex:10 cyl., alum. piston = .030 run. clrnce.

10 - .030 =

9.970 rider O.D.Running clearance Rider O.D.Rings & RidersAny Questions?