The shimmy damper (or dampener) is
a hydraulic shock absorber installed on either the nose or
main wheel forks and is attached to the aircraft structure. … The slow movement of the piston allows the wheels to pivot so the aircraft can be steered on the ground.
How does a shimmy damper keep a nosewheel from shimmying?
A shimmy damper consists of an oil filled cylinder, with a push–pull rod attached to a disk inside the cylinder. … A
small hydraulic or pneumatic shock absorber installed between the nose-wheel
fork and landing gear structure to prevent or minimize nose-wheel shimmying during takeoff and landing.
How does the shimmy damper work?
A shimmy damper uses a cylinder filled with hydraulic fluid or a rubber/lubricant combination
to prevent rapid movement of the nosewheel
, while not interfering with slower operations.
What are the several ways to reduce shimmy?
- First, look for any un-dampered nose gear movement. This is motion of the nose tire without the shimmy damper moving. …
- Next, remove the shimmy damper attachments. …
- Nose gear rigging is also important to prevent shimmy.
Which shimmy damper uses a rubber piston?
The LORD Shimmy Damper
utilizes surface-effect technology. LORD has replaced the hydraulic piston in the traditional damper with a fully-bonded rubber piston that presses out against the inner diameter of the housing. This rubber piston then rides on a very thin film of grease.
What is shimmy in aviation?
1. Introduction. Shimmy vibration is a very important common phenomenon in the landing gear system during either the take off or landing of an aircraft. … In the landing gear of a taxiing aircraft, shimmy is
a state of self-excited oscillations
, caused by the dynamic reaction forces between elastic tires and the ground.
What is a wheel shimmy?
In general, steering wheel shimmy refers
to visible or tactile steering wheel shake
. … Vibrations that occur at low speed and worsen progressively, usually referred to as a steering “wobble” at low speeds, are likely related to physical imbalances, such as tire flat spots, bent wheels or axles, or seized joints.
What is landing gear shimmy?
Shimmy vibration is a common phenomenon in landing gear systems during either the take-off or landing of aircrafts. It is the
state of self-excite oscillations in lateral and torsional directions caused by the interaction between the tires and the runway
.
How does emergency gear extension work?
An emergency landing gear extension is quite simple: pushing the emergency gear extension lever
on the pilot’s side of the console between the front seats opens up the gear-up fluid lines
. Without pressure, the gear will fall out of the gear wells and lock itself down.
What is a centering cam?
Centering Cam. A cam in the
nose-gear shock strut that causes the piston to center when the strut fully extends
. When the aircraft takes off and the strut extends, the wheel is straightened in its fore-and-aft position so it can be retracted into the wheel well.
What is a vane type shimmy damper?
A vane-type shimmy damper is sometime used. [Figure 6] It uses
fluid chambers created by the vanes separated by a valve orifice in a center shaft
. As the nose gear tries to oscillate, vanes rotate to change the size of internal chambers filled with fluid.
What causes nose wheel shimmy?
An imbalance in the nose tire and wheel assembly can cause a vibration in the nosegear. Uneven tire wear can also cause nose vibrations.
An overly inflated nose tire
can also contribute to a nosewheel shimmy. … A damper that is low on fluid or is excessively worn internally will most assuredly result in a nose shimmy.
What are the two kind of controllers which control the nose wheel steering system in large aircraft flight deck?
Control of the steering is from the flight deck through the use of
a small wheel, tiller, or joystick
typically mounted on the left side wall. Switching the system on and off is possible on some aircraft. Mechanical, electrical, or hydraulic connections transmit the controller input movement to a steering control unit.
What causes wheel wobble at high speed?
The most common cause of vehicle wobbles in this speed range is a bent wheel or mildly out of round tire. … The most common cause of vehicle shakes at 50 mph or higher is
tire balance
. Again, transmission or drive lines can cause this, but the tires should be the first thing to have checked.
What does death wobble feel like?
When death wobble occurs, you will feel
a shaking in the steering wheel
, which will increase or decrease with speed, and depending on severity, shaking throughout the cab.
