Hi Roger;
There are as many different designs of nose gear steering systems and shimmy dampers as there are landing gear designers.
In general, if the nose gear has a scissor, the top of the upper link will be attached to a collar that can rotate around the outside of the strut housing. If there is powered steering, this collar can be rotated by a hydraulic cylinder, an electric actuator, or cables that are connected to the rudder pedals. If there is no powered steering (usually called a castoring nosewheel) the collar's movement will be restricted by some combination of springs, rubber or fluid dampers, or carefully controlled friction between the collar and the strut. This restricted motion prevents shimmy loads from being felt in the aircraft, and prevents divergent shimmy of the nose tires.
Many older aircraft, and some current small aircraft, use a shimmy damper that consists of a spring and rubber pad stack up at one of the scissors joints - usually the middle joint, or sometimes the joint between the top of the upper link and the strut. This package will allow a very small steering movement, but the purpose is not to steer the aircraft, but just to dissipate the shimmy energy at critical frequencies (like the natural frequencies of the nose gear strut or the forward fuselage).
To add to the confusion, older aircraft may not have any powereed steering or castoring of the nosewheel. Steering is accomplished by scuffing the tires (that is, dragging the tires sideways as the aircraft turns). These aircraft may still need a shimmy damper, as the free play in the scissors joints may allow enough movement for divergent shimmy to develop at some speeds.
All this is a roundabout answer to your question. Almost all nose gears that can steer or castor (and many that cannot steer or castor) will have some method of controlling shimmying. It may be a separate spring pack or damper called a "shimmy damper" in the aircraft parts list, or it may be built into the steering mechanism, the castoring mechanism, or the joints of the scissors.
Hope you followed all this. There will be a quiz next week.
