737 Tiller

[jackpilot]

Just spent a few hours to get a square end from a round bar!!! no fancy machine just a file!
Building a tiller mechanism (overbuilt as usual)
Will add springs and a slider pot.
Question: is there a strong self centering sytem on the real plane ?

[markuspilot]

Yep !
As to how "strong" strong is, is a matter of opinion.
feedback on the tiller would be stronger than the control column.

Anything to get it back to center.

[Nat Crea]

I used a couple of nice medium springs Jack.

Like Mark said, nice and firm but not arm breaking, and return to centre.

Nat

[jackpilot]

prototype nearly OK
Feel is pretty good, no play and strong centering (within a few degrees.)
One tip: as some springs are noisy when streched just slide one foam earplug in, at each end. They expand and stay there. 
I hesitate between a slider and a reg pot.
TBC

[Maurice]

Very clever design; looks fantastic. I don't see any advantage between a regular pot or a slider for the tiller. Whatever is easiest to adapt would be my choice.

Maurice

[MLeavy737]

Looks great Jack!!

wish i knew more of how that tiller feels.. I would be making an extra 50k a year!!

i only get a crack at that thing in the CAE sims once a year on checkrides and im pretty sure there is a good centering force when taxing.. I have a checkride coming up again next month or so, ill give ya a better answer then

Mike L

[N737AG]

Jack

Here is a picture of the real nose gear steering quadrant. It is located under the cockpits floor. It is connected to the tiller by the pulley cables you see at the circular pulley.

This quadrant has 4 basic functions :

a) Centering of the tiller, which is achieved by the arms at the center of the quadrant and the big spring

b) Force feel, which is achieved by the big spring. I did some force measurement. To start moving the tiller you have to apply a force of approx. 2.5 kg. At the end of the movement the applied force is almost 6 kg - the more you turn, the harder it gets.

c) Pedals interconnect. From the rudder pedal quadrant (left of the picture) an arm connects to the tiller quadrant (it is that diagonal arm you see on the left of the picture). The tiller allows the nose gear to rotate up to 75 degrees in each direction. The rudder pedals give the tiller quadrant a slight rotation, allowing the nose gear to rotate only about 7 degrees in each direction. On the ground the rudder pedals are used to give a minor nose gear steering while on the runway, since the captain (if he is the pilot flying) must have one hand on the yoke and the other on the throttles.

d) Pedal disconnect : as soon as the nose gear is off the ground (the oleo strut is completely extended), a mechanism on the quadrant phisically disconnects it from the rudder pedals via an excentric pulley. This is to insure that after takeoff the nose gear is straight when going in to the wheel well. It also insures that on touchdown the nose gear is straight, despite the pedal inputs to the rudder.

Axel

[Trevor Hale]

WOW! Axel, incredible information and perfect explanation.  Cheers for the help.

Trev