canopycandy 0 #1 October 10, 2003 I know it's silly. But really, I'm wondering what makes it ... you know, go. And as a very silly postscript to that question -- can it freeze? Quote Share this post Link to post Share on other sites
rigging65 0 #2 October 10, 2003 Your altimeter (most of them anyway) works based on a mechanical bellows. There is a piece of metal that acts as a diaphragm on the bottom of the case. As you go up in the plane, the pressure drops, this allows the the diaphragm to flex, pushing against a post. The moving post pushes some gears around. The gears are integrated into a wound spring which gives them something to push against as they turn (so they will wind/unwind smoothly). As the gears move, they twist an axel and the result is the needle on the face moving. Often an alti "sticks" because the needle is bent or off center and is rubbing against the face of the alti, thus providing more friction than the weak little spring can overcome. Sometimes the little bits (gears, springs, posts, etc.) inside the alti slip out of place. Generally they can be easily put back in place...if you can get to them. Many newer altimeters don't give you access to the guts. Probably the easiest one to work on is the old Alti IIs. The big ones. We've fixed a bunch of them over the years without having to send them back...something you can't do easily on many other types, of course the big ol' Alti IIs aren't as cool looking as the newer models... "...and once you had tasted flight, you will walk the earth with your eyes turned skyward. For there you have been, and there you long to return..." Quote Share this post Link to post Share on other sites
