tiller arm/nose steering

[PPRuNeUser0179]

hi guys

I have been looking at B737/8's and A320 series and the jetstream 41 and I seem to notice this little semi-circle "arm" on the left hand side of the captains seat.Further research has taught me that this is the nose wheel steering column.I went onto a UK Boeing 737 technical website (The Boeing 737 Technical Site (http://www.b737.org.uk/)) that stated "when taxiing,it is recommended that pilots use the tiller arm steering system and during the takeoff roll,they use the rudder control pedals.)
1.)My first question is:can you taxi a 737/A320 using the rudder pedals and disregard the tiller arm?
2.)And my second question is,do all planes (C152 and up)use a tiller arm or not?If not,do they use the rudder pedals (as I assume) or do they use something else?

I have not noticed a tiller arm in a B58,C172,KINGAIR series and the piper cherokee.But I may have not noticed it.

Thanks in advanced

Daniele

[aviatorhi]

Most small aircraft use the rudder pedals exclusively (some, like the Aerostar, have alternate systems, though).

Larger aircraft (let's say 12,500 lbs and up) usually feature some form of powered or direct steering, this can be anything from a wheel with a wire spool going to the nose gear, a micro-switch that drives electric motors, a lever like in Short aircraft, or a tiller system like you see in the Boeings.

In the case of the 737 the tiller can turn the nose wheel up to 78 degrees left or right of center. The rudder pedals only allow 8 degrees left or right. A good technique (if you have steering that isn't pulling to one side or the other) is to us the tiller for the bendy bits and the pedals for the straight bits. Typically it is not advisable to touch the NWS at high speed due to numerous reasons (control at high speed, skidding the nose tires, etc.), but it does come in handy to make a high speed turnoff.

[PPRuNeUser0179]

Thanks At

That helped alot.I was quite confused.As I said,I had never seen this before but now I have a better understanding of it and its main purpose.

[AerocatS2A]

There are a number of different steering system, even on small aircraft. The Aero Commander has hydraulic steering that is controlled by the first few inches of brake pedal movement. So moving the rudder pedals does nothing to the steering, but if you push on a toe brake a little bit you get steering in that direction first followed by brake action if you push it harder. Takes a bit of getting used to, but is very good once you have the hang of it. The BAe146 has tiller steering only, that is, the rudder gives no authority over the nose-wheel steering, so you have to use the tiller for everything up to about 60 knots when the rudder gets enough airflow to become effective. The Dash 8 is more like the B737 where the rudder has limited (7º) authority over the nose-wheel and anything beyond minor corrections needs the tiller.

Some small aircraft have castoring nose-wheels, some have the nose-wheel connected to the rudder via cables and springs. The Tiger Moth has its tail skid connected to the rudder so it moves when the rudder moves, but because it is a skid, it doesn't always give much directional control, particularly if you have to taxy on tarmac.

[Notso Fantastic]

I flew almost all Boeings. They all use a single short tiller arm to the left side of the captain. Using it is the only way to get around sharp corners. The rudder pedals have some tie in on the nosewheel steering, but only about 1/10 the effect, so rudder steering is only practicable with gently steering requirements, such as minor steering on take-off or on straight taxiways. Some airlines buy the extra option of a second tiller on the right hand side. Following B737s in particular, it's peculiar seeing how they in fact crab along taxiing. The dynamics are a bit vague, but the main undercarriage legs obviously twist slightly. It's odd to see them going slightly sideways- even the pilots would be unaware, but you can see it following them.

Once you get below F27/HS748 twin turboprop size, I believe tillers are quite unusual, and never fitted to smaller aeroplanes.

The other really weird thing to see in aviation is the way on the ground, the DC9/MD82 series have elevators that are flapping freely apparently unconnected to anything!

[anotheruser]

I was always wondering, what is the steering ratio of a tiller, I mean, how many degrees do you have to move the tiller to deflect the nosewheel by one degree? Is it like the steering wheel in a car where you sometimes have to turn the steering wheel twice to fully deflect the wheels?

[NSEU]

On a Boeing 747-400, (a maximum) 150 degrees tiller movement (from centre) results in 70 degrees nosewheel movement.

Rgds
NSEU

[Dan Winterland]

On the A320/330/340/380, the rate is progresssive with the first tiller movement only making small deflection of the nosewheel with increasing deflection rates as the whell is moved further. On most Boeings, the tiller on the F/Os side is an option wheras it is standard on Airbus aircraft.