Nose wheel steering by pedal: electrical conditions

[Hardy Heinlin]

Theory:

There is one significant event in the life of a nose gear.

This event decides whether the nose gear can be steered or not.

It's the event of the touchdown.

If any nose steering CB is powered during touchdown, the nose gear will be steerable.

If both nose steering CBs are depowered during touchdown, the nose gear won't be steerable.

The future of the nose gear steerability is decided upon touchdown. After touchdown, these CBs play no role anymore.

No electrical steering ratios or limiters are required. Nose gear steering is possible by pure hydraulic force and pilot muscles.

_________________________________________________


Anybody disagree with this theory?


Cheers,

|-|ardy

[Will]

I potentially disagree for theoretical reasons, but since I don't know anything about the 747, I won't join the fray.  I look forward to reading the answers of more knowledgable people.

[dutch57]

Hardy goodevening,

Nose gear steering is pure hydraulics, pilot musle,nose gear position extended/retract simple as that.

Saying this , will raise the question the c/b`s, yes you have them but they are for rudder pedal steering a primairy and altenate electric motor which connects the rudder pedals to the tiller steering system , but limited in its turn radius.
Pedal steering is used during highspeed landing or take off roll.
operated by 2 electric actuators which get their signals from the nose gear squat switches via the pseu.

sincerly Bob

[Will]

So pulling the CBs mid-roll would deactivate the electric steering via the rudder pedals, but would not affect the hydraulic steering via the tiller?

[dutch57]

Will goodevening,

Yes pulling the c/b`s , will NOT affect the tiller steering.

sincerly Bob

[Hardy Heinlin]

Thanks! Please note the subject:

Nose wheel steering by pedal


:-)

Sorry, I should've repeated this in my text.

...

Again:

Pedal steering is possible only if any of those two CBs were powered during touchdown. After touchdown, pedal steering is possible even if both CBs get unpowered after touchdown.

Right or wrong?

[dutch57]

Hardy,

Yes , you are right,

sorry i should read more carefully, i am looking as a engineer.

Bob

[John H Watson]

Do you agree with the "any" part of Hardy's statement, Bob?

That is, did you confirm my earlier statement that only one actuator needs to be in the ground position for landing (and subsequent steering control), but two actuators need to be in the air mode to disengage the pedals from the steering mechanism.

Of course, we both know that steering is impossible once the nose strut extends.

Another question if I may ask: If both actuators didn't disengage on takeoff, would the rudder pedals still be attached to the tiller (i.e. would you get movement of the tiller if you moved the rudder pedals in the air?)  

Rgds

JHW

[the mad hatter]

Yes Mr Hardy you are correct!

[dutch57]

John,

Yes I agree , also with your statement , to say short , one to engage 2 to dis engage.

About your second question, I have to check the AMM to be sure , but i think yes the tiller will move when you give a rudder input. And pedal steering is not dis engaged in flight.

Bob