ELEMENTS: A SEPARATE PIECE

Seals let it all happen

- KEVIN CAMERON

We immediately think of oil and coolant containment—oil seals, O-rings, and gaskets—in this connection. But combustion gas is the fluid that produces power, so we have to add the sealing functions of piston rings, and intake and exhaust valves to our list.

Long-lasting oil seals and O-rings are as recent as the synthetic rubbers that can make them impervious to gasoline, oil, brake fluid, or water. Consult Parker Hannifin’s online Fluid Power Seal Design Guide for compatibility. Retaining oil in motorcycle engines, forks, and wheel bearings are round dual-lip oil sealswith one lip backed by a slender coil garter spring that holds the lip facing the fluid in constant contact with the shaft. Dimensions are the obvious ones—OD, ID, and thickness. The other seal lip is there to exclude dust from the sealing zone.