All Lockheed L-1011 models used tapes for the Trailing Edge Flaps position indicator. Tapes are analog instruments that use a color marked tape to indicate values on a vertical scale. In the case of the TE Flaps instrument, the scale indicates the degrees of flaps extended on the outside and the maximum flaps extend speed in Knots on the inside. The instrument that I show you here is very similar to the instrument in use with the L-1011, however, it is from an Airbus A300. The L-1011 has a slightly different speed/flap range. However, the instrument is still good enough to illustrate the mechanics of the device.
By the way, the TE FLAPS indicator has great back illumination !
The instrument case is held in place by two screws on the backside of the instrument.
Once removed, the instrument casing slides right off and reveals the two discrete tape mechanisms for the right and the left hand side TE FLAPS tapes.
The top view shows the two Control Transformer synchros (CTs) with the blue end caps and the two DC torque motors.
The two sides are basically symmetrical - as can be seen in this right-hand-side view.
Bottom view
Left hand side view
The mechanical elements that drive the tapes are very similar to a tape cassette player (for those who still remember what that was). There is a take-up reel and the supply-reel. The gear that connects the CT also doubles as the supply-reel with the tape wound onto it and the send largest, spring loaded wheel, acts as the take-up reel.
The motor drive also links to a wheel that acts as a mechanical limiter and prevents the motor from over-torquing the tape and breaking it.
The next image shows the motor energized with 2.5V ... which will develop about enough torque to extend the tape out to 22º flaps extended. As you can see the motor on the left hand side of the instrument drives the tape on the right hand side on the instrument face.
