Aircraft nose wheels facilitate the ease of steering while the vehicle is traveling on the ground, especially during takeoff and landing. Moreover, without the implementation of shimmy dampers, aircraft taxiing at high speeds may experience shuddering of the nose wheel; shimmy dampers are piston-like devices that employ cylinders filled with either hydraulic fluid or a rubber/lubricant combination to prevent rapid movement of the nose wheel without impacting specific operations. In the case of a shimmy damper failure on the taxiway or runway, the aircraft will shake violently, and passengers may feel as though the aircraft may fall apart. Despite this extreme vibration, the plane and passengers will be safe as long as weight is taken off of the nose wheel by the pilot promptly pulling back slightly on the yoke.
Older damper systems feature a plate with a fixed hole that allows hydraulic fluid to move through for proper steering at lower speeds. When the airplane makes a turn at these speeds, fluid moves from one end of the cylinder to the other with ease, but if the aircraft is moving at higher speeds, fluid cannot move through as quickly. In this case, the nosewheel is stabilized to prevent shaking. A second system created by Lord Corporation features a fluid-free shimmy damper that uses a rubber formulation, along with high-tech lubricant. As such, there is no chance of a fluid leak, that of which has the potential to deteriorate aircraft performance and cause shuddering when traveling down the runway.
Shimmying is caused by factors such as wheel imbalance, uneven tire wear, or loose joints in aircraft nose strut scissors and steering mechanisms. The most common fix for a shimmy issue is to ensure that all the bushings, bolts, and rod end joints are firmly in place and free of excessive play before assuming fault with the shimmy damper itself. However, it is a mistake to simply repair the loose components without servicing the damper at the same time. In fact, Doug Haughton of Avian Aeronautics has expressed that nearly 90 percent of the shimmy dampers that arrive at his shop had not received necessary routine maintenance, and this causes expensive components to become unviable.
Shimmy dampers do not prevent oscillations at the source; rather, they are critical instruments used to ensure that minor vibrations and oscillations remain damped and under control. This reduces overall wear on every other joint and aircraft system. Tight nose gear systems allow aircraft shimmy dampers to function and control minor oscillations, while the shimmy damper protects the nose gear from excessive wear. Therefore, these two systems rely on one another for their proper functioning.
The principle that shimmy dampers work on is as follows: a shaft with a piston fixed at its midpoint slides fore/aft inside the cylinder containing hydraulic fluid. There is a hole in the piston that permits the fluid to pass through at a metered rate which forces the fore/aft motion of the rod to behave in a slow and controlled manner. This dampens rapid movements of the steering mechanism it is attached to. In addition, O-rings create seals around the piston shaft and end caps at both ends of the cylinder.
Those in the market for high-quality aircraft shimmy dampers should look no further than Integrated Aviation Hardware, where we are dedicated to our customers. As a proud AS9120B, ISO 9001:2015, and FAA AC 00-56B accredited parts distributor, you can rely on the caliber of our offerings, many of which are subject to rigorous quality assurance measures. Moreover, we ship our parts alongside their qualifying certifications and manufacturing trace documentation, as applicable. With more than 2 billion new, used, obsolete, and hard-to-find parts available for immediate purchase in our inventory, you can rely on us to supply you with what you need for your particular application. Sourcing our products from trusted global manufacturers and offering expedited shipping rates keeps our customers returning for our products and services time and time again. Call or email us today to get in contact with a representative who can assist you throughout the parts procurement process.
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