The damper looks from the outside like a boring old piston. Actually, there are exciting things going on inside. In older systems, a plate inside the damper has a fixed, tiny hole allowing hydraulic fluid to pass easily through for normal steering at lower speeds. Turn the airplane, and the fluid squirts from one end of the cylinder to the other. At higher speeds, the fluid can’t get through as fast as the nosewheel wants to shimmy, and the nosewheel is stabilized, preventing shaking. Pretty exciting, eh? You’ll think so if it ever doesn’t work.
A second system, one made by Lord Corporation, offers a fluid-free shimmy damper. Instead of hydraulic fluid, it uses a rubber formulation with high-tech lubricant. There’s no fluid to leak. In the hydraulic system, just 20 drops of leakage can deteriorate performance and send you shuddering down the runway.