Boeing 737 OEM Steering Tiller Installed

/

oem 737-400 steering tiller mounted to bespoke aluminium plate

The steering tiller is an often overlooked piece of hardware for many virtual flyers.  The steering tiller provides greater control of the aircraft during taxi operations, and if calibrated correctly works very well.

OEM B737-400 Steering Tiller

The tiller has been salvaged from a 737-400 series aircraft and is identical to the tiller used in the Next Generation aircraft.  The actual OEM part is only the black handle and white arrow.  The remainder of the unit has been custom fabricated to allow easy attachment to the inside wall liners of the flight deck.

The simulator does not have a shell and liner at the moment; therefore, I've attached two pieces of grey-coloured wood to the unit to enable temporary installation to the forward left of the Captain's seat.  

A single potentiometer has been used allow calibration of the tiller mechanism.  A metal strip connects the potentiometer with a metal plate that connects to the the central area of the tiller mechanism.  As the steering tiller is turned left or right, the metal plate moves to and fro with a corresponding movement in the metal strip which registers on the potentiometer (see picture).

To create tension when the steering tiller is moved, several heavy duty springs have been used.  Although rudimentary in design, the tension of the springs provides a reasonable and constant pressure.  The springs also allow the handle to center itself easily when released.  Springs are renowned for creaking when they move and to remove this noise, heavy duty lithium grease has been applied to the upper parts of the spring heads where they join the metal. 

Tiller mechanism showing springs and potentiometer.  A linear potentiometer has been used in favour of a rotary potentiometer. Springs provide tension to center the tiller

Interface Card and Calibration

The tiller is connected directly to a Leo Bodnar BU086A interface card, although any joystick card such as a PoKeys card can be used.  A USB cable then runs from the interface card to the main computer.  To allow easy connection to the interface card (Leo Bodnar card) a female JR servo wire security clip has been used.  

The steering tiller requires careful calibration if it's to operate correctly.  Calibration is initially through Windows and then FSUIPC.  Using FSUIPC enables greater accuracy to be achieved.

The steering tiller, when calibrated through FSUIPC does not create an independent tiller axis but piggybacks on the movement of the rudder axis.  The developer has ingeniously written code that enables the tiller to be activated when groundspeed is under 60 kias.  Above this speed the rudder is activated.

How to Calibrate the Steering Tiller

  1. Connect the interface card to the computer via the USB cable.

  2. Using Windows, calibrate the axis of the interface card (if using Windows 7 type into the search bar joystick and select "Joystick Calibration").

  3. Following the on screen instructions, move the steering tiller handle forward and aft.  Then save the setting.

  4. Open Flight Simulator and then open “Settings/Control” in the FSX menu.

  5. Ensure that any joystick commands relating to the interface card are not registered by FSX.  If so, delete them and save.

  6. Open Flight Simulator and then open FSUIPC settings.

  7. Select the FSUIPC “Axis Assignment Tab”.  Then move the tiller handle to activate the calibration software.  (you will observe the numbers moving).

  8. Select from the left side of the screen the tab that says ”Type of Action Required”,  Select "Send Direct to FSUIPC Calibration".  Then open the menu box and scroll down to “Steering Tiller”.

  9. Open the “Joystick Calibration” tab in FSUIPC.  

  10. Scroll through the 11 entries searching for steering tiller (9/11).  When "Steering Tiller" is found, click the SET button which will open three (3) further buttons.  Each button refers to a position on the steering tiller axis.

  11. Turn the steering tiller to the left and click the RIGHT button.  Then turn the tiller to the right and select the LEFT button.  With the tiller in the central position click the MIDDLE button.  Oddly, on some setups the opposite is required.  If calibration fails, try again using the opposite direction.

  12. For more precise and accurate calibration, you may want to use the "Slope" and/or "Null Zone" functionality.

The steering tiller should now be calibrated and ready for use.

Troubleshooting and Suggestions

Some known problems that are easily solveable are:

Leo Bodnar 086A interface card (joystick card)

A:  Only use the steering tiller at very low ground speeds.  If you turn the tiller to the full left or right and the speed is too great, the aircraft may remain stationary or slip; the reason being the nose wheel is locked at a right angle to the direction of travel.  I find the tiller works best turning the handle slowly.

B:  The direction of aircraft travel is opposite that of the tiller handle.  If this occurs, check your FSUIPC settings.  You may have to tick (check) the box that says REV.  REV reverses the direction of the axis (left to right and right to left).

C:  If the tiller exhibits sensitivity issues or if you require a dead zone, open FSUIPC and program the SLOPE function and/or set a NULL ZONE.

D:  If you have issues with the tiller not working correctly, do the calibration again in Windows and FSUIPC.  If calibrated correctly, the tiller will change to rudder control at 60 knots.

OEM is an acronym for Original Equipment Manufacturer.