Torque Link / Shimmy Damper pt 1
By Jack Johnson on Wednesday, Mar 15th 2017 13:33Z
So in a nutshell, this is how the torque link and shimmy damper works.
The sliding piston (the lower part of the landing gear) is essentially free to rotate in the static piston (which is attached to the aircraft). The torque link connects the two pistons with a two-part mechanism (the torque link), that transmits torsion load from the wheels to the airframe.
With the gear extended in flight, the apex of the torque link is closer to the centre-line of the shock strut. Hence, the ability of the shimmy damper to dampen shimmy is reduced (force x distance).
Torque Link / Shimmy Damper pt 2
By Jack JOhnson on Wednesday, Mar 15th 2017 13:34Z
As weight is put on the wheels, the shock absorber closes, putting the Torque Link apex further from the shock strut centreline. At this point the torque link and shimmy damper becomes more effective at preventing shimmy.
The shimmy damper is basically a big baffles with oil, where load is dissipated (like in a shock absorber) mechanically. The force with which the oil is forced through the shimmy damper depends on the distance from the Torque Link apex to the shock strut centreline.
So, a ultra soft float landing could contribute to failures due to shimmy.