Landing gear with caster and variable shimmy damping
An aircraft landing gear shimmy damping device for aircraft landing gear with castering may include a centering cam engaged in a curvic slot in an internal diameter of an aircraft landing gear wheel spindle when the landing gear wheel is aligned with forward ground travel of the aircraft, engaging a landing gear wheel shimmy dampener. The centering cam may be pushed out of the curvic slot when the aircraft begins to turn, disengaging the landing gear wheel shimmy dampener, and may slide back into the curvic slot and (re)engage the shimmy dampener, when the landing gear wheel is realigned with forward ground travel of the aircraft.
1. An aircraft landing gear shimmy damping device for aircraft landing gear with castering, the device comprising:
a centering cam engaged in a curvic slot in an internal diameter of an aircraft landing gear wheel spindle when at least one landing gear wheel is aligned with forward ground travel of the aircraft, engaging a landing gear wheel shimmy dampener, the centering cam configured to:
be pushed out of the curvic slot when the aircraft begins to turn, disengaging the landing gear wheel shimmy dampener; and
slide back into the curvic slot and engage the shimmy dampener, when the landing gear wheel is realigned with forward ground travel of the aircraft.
2. The aircraft landing gear shimmy damping device of claim 1 , wherein the centering cam is further configured to transfer turning torque through a damper shaft engaged with the shimmy dampener.
3. The aircraft landing gear shimmy damping device of claim 1 , further comprising a damper shaft engaged with the shimmy dampener, and wherein the centering cam is further configured to transfer turning torque to the damper shaft.
4. The aircraft landing gear shimmy dampener device of claim 3 wherein aircraft landing gear shimmy damping is varied by exchanging the landing gear wheel shimmy dampener.
5. The aircraft landing gear shimmy dampener device of claim 4 wherein the landing gear wheel shimmy dampener is exchanged by disengaging the landing gear wheel shimmy dampener from the damper shaft and engaging a different landing gear wheel shimmy dampener with the damper shaft.
6. The aircraft landing gear shimmy dampener device of claim 1 , wherein the centering cam is biased into, and back into, engagement in the curvic slot by an upper spring and/or a lower spring.
7. The aircraft landing gear shimmy damping device of claim 6 , wherein the centering cam is further configured to be held against the internal diameter of the aircraft landing gear wheel spindle by the upper spring and/or the lower spring.
8. The aircraft landing gear shimmy dampener device of claim 1 , wherein the aircraft landing gear wheel spindle comprises an aircraft landing gear yoke.
9. The aircraft landing gear shimmy dampener device of claim 1 , wherein the aircraft landing gear wheel spindle is configured to rotationally mount the at least one landing gear wheel, the landing gear wheel spindle comprising a hollow pivot shaft configured to be rotationally mounted to a landing gear mounting arm, the hollow pivot shaft defining:
a reduced diameter bore portion;
a further reduced diameter bore portion within the reduced diameter bore; and
the curvic slot defined in an inner surface of the further reduced diameter bore portion, extending across the further reduced diameter bore portion, open to the reduced diameter bore portion.
10. The aircraft landing gear shimmy dampener device of claim 9 , further comprising:
a damper shaft rotatably retained in the hollow pivot shaft, the damper shaft engaging a torsional damper torsionally anchored to the landing gear mounting arm;
a centering slider retained longitudinally displaceable about the damper shaft in the hollow pivot shaft, the centering slider integrally comprising the centering cam, extending from the centering slider, the centering cam biased:
into engagement into the curvic slot when the at least one landing gear wheel is generally aligned longitudinally with a fuselage for forward travel of the aircraft, engaging the torsional damper with the at least one landing gear wheel; and
along the curvic slot and out of the curvic slot into the reduced diameter bore portion, disengaging the centering slider from the damper shaft and allowing the landing gear wheel spindle and mounted at least one landing gear wheel to rotate disengaged with the torsional damper, as the at least one landing gear wheel moves out of longitudinally alignment with the fuselage; and
to slide back into the curvic slot, as the at least one landing gear wheel moves back generally aligned longitudinally with the fuselage for forward travel of the aircraft, reengaging the torsional damper with the at least one landing gear wheel.
11. The aircraft landing gear shimmy dampener device of claim 10 , further comprising
an upper spring disposed above the centering slider in spring engagement with the centering slider and the landing gear wheel spindle, and a lower spring disposed below the centering slider in spring engagement with the centering slider and the landing gear wheel spindle, the upper and lower springs providing the biasing of the centering cam by biasing:
the centering slider into engagement of the centering cam into the curvic slot when the at least one landing gear wheel is generally aligned longitudinally with the fuselage for forward travel of the aircraft, engaging the torsional damper with the at least one landing gear wheel; and
the centering slider along the curvic slot and the centering cam out of the curvic slot into the reduced diameter bore portion, disengaging the centering slider from the damper shaft and allowing the landing gear wheel spindle and mounted at least one landing gear wheel to rotate disengaged with the torsional damper, as the at least one landing gear wheel moves out of longitudinally alignment with the fuselage.
12. An aircraft comprising:
a fuselage; and
a landing gear comprising:
a landing gear mounting arm extending from the fuselage;
a landing gear wheel spindle configured to rotationally mount at least one landing gear wheel, the landing gear wheel spindle comprising a hollow pivot shaft configured to be rotationally mounted to the landing gear mounting arm, the hollow pivot shaft defining:
a reduced diameter bore portion;
a further reduced diameter bore portion within the reduced diameter bore; and
a curvic slot defined in an inner surface of the further reduced diameter bore portion, extending across the further reduced diameter bore portion, open to the reduced diameter bore portion;
a damper shaft rotatably retained in the hollow pivot shaft, the damper shaft engaging a torsional damper torsionally anchored to the landing gear mounting arm;
a centering slider retained longitudinally displaceable about the damper shaft in the hollow pivot shaft, the centering slider comprising an integral centering cam extending from the centering slider; and
an upper spring disposed above the centering slider in spring engagement with the centering slider and the landing gear wheel spindle, and a lower spring disposed below the centering slider in spring engagement with the centering slider and the landing gear wheel spindle, the upper and lower springs biasing:
the centering slider into engagement of the centering cam into the curvic slot when the at least one landing gear wheel is generally aligned longitudinally with the fuselage for forward travel of the aircraft, engaging the torsional damper with the at least one landing gear wheel; and
the centering slider along the curvic slot and the centering cam out of the curvic slot into the reduced diameter bore portion, disengaging the centering slider from the damper shaft and allowing the landing gear wheel spindle and mounted at least one landing gear wheel to rotate disengaged with the torsional damper, as the at least one landing gear wheel moves out of longitudinally alignment with the fuselage.
13. The aircraft of claim 12 , wherein the landing gear mounting arm comprises a landing gear tailing arm.
14. The aircraft of claim 12 , wherein the landing gear wheel spindle comprises a landing gear yoke.
15. The aircraft of claim 12 , wherein the upper spring and lower spring are disposed in the hollow pivot shaft in engagement with the landing gear wheel spindle, with the centering slider disposed in spring bias between the upper spring and the lower spring.
16. The aircraft of claim 12 , wherein torsional damping is varied by exchanging the aircraft landing gear shimmy damper.
17. The aircraft of claim 16 , wherein exchanging the torsional damper further comprises disengaging the torsional damper from the damper shaft and engaging a different torsional damper with the damper shaft.
18. A method for providing aircraft landing gear castering and shimmy damping, comprising:
engaging an aircraft landing gear shimmy damper by engaging a centering cam of a damper shaft in a curvic slot in an internal diameter of a landing gear wheel spindle when a landing gear wheel is aligned with forward ground travel of the aircraft;
pushing the centering cam out of the curvic slot when the aircraft begins to turn, disengaging the aircraft landing gear shimmy damper; and
sliding the centering cam back into the curvic slot, when the aircraft returns to a straight-line travel, reengaging the aircraft landing gear shimmy damper.
19. The method of claim 18 , further comprising varying providing aircraft landing gear shimmy damping by exchanging the aircraft landing gear shimmy damper.
20. The method of claim 19 , wherein varying providing aircraft landing gear shimmy damping by exchanging the aircraft landing gear shimmy damper further comprises disengaging the aircraft landing gear shimmy damper from the damper shaft and engaging a different aircraft landing gear shimmy damper with the damper shaft.