A torsion bar spring connecting the suspension on either side of the vehicle. When a vehicle rolls on the side and a turn, the suspension at the out side wheel compresses and the suspension at the inside wheel extends. The stabilizer bar that connects them twist to apply a counteracting forced to hold the vehicle closer to level.
Spring steel rod wound into a coil that supports the vehicles weight while allowing suspension movement.
Usually the top two rings in the piston, they form a seal between the piston and cylinder wall to compress the air fuel mixture in the cylinder.