Bob & Ron's vintage Link Trainer (aka Blue Box) restoration adventures
The remote instrument box includes three primary Telegon instruments, each with identical 5-pin AN connectors. To avoid confusion, Link labeled them with small stamped metal tags. “AS” air speed, “VS” vertical speed, and “ALT” altimeter. Those little labels withstood the test of time.
Sometimes parts are worn out or broken beyond repair. The original part #8581 (right) is a lever and bracket assembly that supports a pivot point for linkages going back to the tachometer regulator. Like several brackets in the fuselage, it is cast from pot metal. This bracket had many cracks and was broken in several places due to fatigue. We made the substitute (left) from aluminum. Ours doesn’t look as cool but is functional.
We recently refurbished the turn and bank indicator regulator bellows for our Blue Boxes. The regulated vacuum output is supplied to a gyro inside the turn section of the turn and bank indicator.
For more details, read the ‘turn and bank indicator regulator bellows’ section under ‘Restoration hints’ in the right column [scroll to bottom for cell phone] , or check out our video.
Update December 1, 2020. The bellows refurbishing did the trick. The turn and bank indicator is now working. Yea!
Our altimeter transmitter was stuck. We opened it up, cleaned the gears and oiled the bearings with synthetic clock oil. The Telegon transmitter motor is magnetically coupled to the gear box. Each side has a tiny Y-shaped magnet; the driving and receiving magnet are spaced about 050” apart as they spin. It’s hard to see in the picture; but the North side of the magnet is marked with a faded red stain. Details are shown in the “Altimeter transmitter” section of “Restoration hints”.
It’s not often that new material is written about the ol’ Link Trainer. The July issue of “Aeroplane Monthly” has a nice introductory article regarding the Blue Box. It includes some interesting facts, and new graphics depicting the trainer’s vacuum system and associated instruments. Ian Bott, a professional graphics designer in the U.K., researched the subject and created the pictorials. He did a nice job presenting a lot of info in a few column-inches. Check out “Aeroplane Monthly” (July 2020) and read a full-sized version of the article.
