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Altimeter

  • silverghost
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25 Oct 2012 22:47 #23779 by silverghost
Replied by silverghost on topic Altimeter
A great way to find you home's accurate starting altitude, along with also being a great way of calibrating your vintage mechanical dash mounted Barometer/Auto Altimeter, is to buy a very inexpensive hand-heald portable Hiker/Camper stye GPS unit as these units all now contain very accurate altitude digital read-outs.
Most can be bought today for between $150. and $300. locally, or on-line. They are also, very easy to use.

This email address is being protected from spambots. You need JavaScript enabled to view it. BRAD HUNTER Huntingdon Valley Pa/Ocean City NJ 215 947 4676 Engineer & RE Developer Brass & Classic Auto, Antique Boat, Mechanical Automatic Music Machine, & Jukebox Collector

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  • xjn001
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24 Oct 2012 17:06 #23768 by xjn001
Replied by xjn001 on topic Thanks
Thanks for your information! This is part of the ACD I really like!

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  • silverghost
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24 Oct 2012 14:52 #23763 by silverghost
Replied by silverghost on topic Altimeter
I believe that before starting your auto road trip you must know your current altitude reading at your starting point to properly zero calibrate your altimeter.
In my case my home's known altitude, just outside of Philadelphia, is 210 feet at my auto's dashboard sitting in my driveway.
You must now turn the outer altitude dial ring, to match the known starting altitude for your starting location, to mate it up to the gauge's current indicated weather Barometer pressure needle reading.
This outer ring is only used to manually calibrate your Auto Altimeter~~~It does Not move on it's own.
In my case I would set the 210 foot outer ring's altitude setting to "Zero" it with the gauge's current indiecated weather Barometer pointer needle.
Then you/I should be good to travel and get fairly accurate altitude readings. ~~~
As we then go up, or down, in altitude the gauge's pointer should point to the proper current altitude as we travel.
All this assumes that your barometric weather pressure reading does not change very much, if at all, during your entire day's trip.

Also usually hidden on the meter's back there is a small calibrating screw that is used to accurately adjust the current Barometer's weather pressure reading at your location..
You need to get this from our local weather station forcast on radio, tv, or another known accurate barometer.
Once this function is first properly calibrated~~ this setting is usually good for many decades. You only need to accurately properly calibrate the Barometer needle setting once.
Not for every trip.
It will usually always remain accurate from this point on.

I do hope this helps answer your Auto Altimeter/Brometer operation question ?

Now~~~
Who here on the ACD forum knows how to change your engine's carb fuel/air mixture settings as you travel higher, or lower, in altitude using this dash mounted Auto Altimeter ?

This email address is being protected from spambots. You need JavaScript enabled to view it. BRAD HUNTER Huntingdon Valley Pa/Ocean City NJ 215 947 4676 Engineer & RE Developer Brass & Classic Auto, Antique Boat, Mechanical Automatic Music Machine, & Jukebox Collector

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  • xjn001
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24 Oct 2012 07:59 #23762 by xjn001
Replied by xjn001 on topic Use of this altimeter
On the altimeter that I have the outer ring turns and moves the scale with the altitude in feet. Is there a certain point to set this? Does the ring move by itself also? I have not taken the altimeter any where in distance from my home so the change in altitude might not show. The barmetric needle moves with the change in my local weather. I wanted to know how to use this gauge in actual practice. I guess I need step by step instructions to use this gauge, Thanks for any answers , also for the details on the inner workings of this altimeter.

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  • silverghost
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24 Oct 2012 02:32 #23758 by silverghost
Replied by silverghost on topic Altimeter
In that case that is where Philipp's extra bi-metalic temp compensation sensor element comes into play to keep the high accuracy of this high quality Altimeter.
The bimetalic temp element only helps overcome the very small inaccuracy caused by temperature expansions & contractions of the Altimeter's metal parts.
The Barometric "Can" capsule sensor is still the main pressure sensor element here.
Most lower quality Atimeters, & Barometers for that matter, do not have this extra temperature compensation feature.

note:
I stand corrected ~
I have slightly edited my prior first post here above to reflect this~~~
It would appear that both Philipp, &amp; I, were only partially correct. <!-- s;-) --><img src="{SMILIES_PATH}/icon_wink.gif" alt=";-)" title="Wink" /><!-- s;-) -->

We all continue to learn everyday from great auto forums like this.

This email address is being protected from spambots. You need JavaScript enabled to view it. BRAD HUNTER Huntingdon Valley Pa/Ocean City NJ 215 947 4676 Engineer & RE Developer Brass & Classic Auto, Antique Boat, Mechanical Automatic Music Machine, & Jukebox Collector

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  • pete kelly
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24 Oct 2012 00:51 #23755 by pete kelly
Replied by pete kelly on topic altimeter
Hi Brad
Lots of info BUT my Duesenberg altimeter is compensated for temperature???????????????????????

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  • silverghost
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23 Oct 2012 23:14 #23754 by silverghost
Replied by silverghost on topic Altimeter
Very cool altimeter gauge !

I would suspect the real reason for having an altimeter on your car's dash,"in the day", other than just curiously knowing how high you were going, was so that you the driver could actually adjust your engine's carb fuel/air mixture settings as the air &amp; it's contained oxygen got thinner as you drove to higher, or got higher at lower altitudes.
This is exactly what is actually done with aircraft engines.
This constant fuel/air mixture adjstment would avoid an overly rich fuel/air mixture at very high altitudes; and an overly lean mixture at much lower altitudes which would effect engine performance, power, &amp; possibly engine life.

Does anyone know if a fuel/air mixture vs. altitude chart was ever printed in the original factory owner's/operations manual of any ACD autos for use along with these Altimeter dash gauges ?

This email address is being protected from spambots. You need JavaScript enabled to view it. BRAD HUNTER Huntingdon Valley Pa/Ocean City NJ 215 947 4676 Engineer & RE Developer Brass & Classic Auto, Antique Boat, Mechanical Automatic Music Machine, & Jukebox Collector

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  • xjn001
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23 Oct 2012 22:50 #23753 by xjn001
Replied by xjn001 on topic Altimeter

This is the altimeter I am using.

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  • oldbanger71
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22 Oct 2012 22:20 #23742 by oldbanger71
Replied by oldbanger71 on topic Altimeter
Hi Brad, thank you for correct explanation. My habit is to say what i belive is right and thankfully, there are people who know better and share their knowledge. A day without learning something new, is a lost day. CORDially Philipp

The more i know, the more i realize that i don't know enough.
812 310 121 S

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  • silverghost
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22 Oct 2012 21:00 #23740 by silverghost
Replied by silverghost on topic Slight Correction
The Altimeter is basically just a simple pressure Barometer that is able to be zero calibrated for local current weather barometric pressure conditions .
The higher you travel the lower the atmospheric pressure.
In the Altimeter's sensor element is a small sealed airtight "can" capsule that is ribbed like a bellows.
Air pressure pushes on this can capsule and squeezes it and it crushes and gets smaller &amp; thinner.
The lower to sea level you are the more this bellows "can" crushes and shrinks &amp; gets smaller as the air pressure get higher.
When you travel to a higher altitude the can relaxes and grows larger with less pressure acting on it in the thinner lower pressure air.
One side of this can is fixed to the main case housing and the other side is connected by small linkage elements to the indicator needle. The sensor can pulls, or pushes on the interconnecting linkage and thus moves the indicator neele up or down. The needle also has a small coiled hairspring to re-set this indicator needle as air pressure changes lower.
There is also a larger bias spring that works along with the bellows "can" to accurately calibrate it for proper pressure readings.

All Altimeters must be manually re-set depending on the local weather's current atmospheric barometric pressure~~~ Before they will read the proper altitude correctly.

The bi-metalic springs mentioned above are used only to indicate temperature as one metal reacts in expansion at a different rate to temperature changes.
These metals are bonded together and cause a slight twist to indicate proper temperature readings.
Bi-metalic springs are Not used in most Altimeters.

I just had to update this thread to slightly correct it as to it's real proper opperation &amp; sensor elemnts. I am a mechanical engineer &amp; designer &amp; i just could not resist <!-- s;-) --><img src="{SMILIES_PATH}/icon_wink.gif" alt=";-)" title="Wink" /><!-- s;-) -->
I have been restoring, repairing, cleaning, lubricating, and calibrating vintage auto &amp; aircraft gauges of all types, as well as spring wound mechanical &amp; electro-mechanical clocks for many decades for my own auto collections as well as for select friends.
Philipp~ I hope I did not step on your toes, &amp; prior post above, too harshly~~~that was never my intent .

This email address is being protected from spambots. You need JavaScript enabled to view it. BRAD HUNTER Huntingdon Valley Pa/Ocean City NJ 215 947 4676 Engineer & RE Developer Brass & Classic Auto, Antique Boat, Mechanical Automatic Music Machine, & Jukebox Collector

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  • oldbanger71
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19 Sep 2012 16:44 #23577 by oldbanger71
Replied by oldbanger71 on topic Altimeter
To my general information, it works with bi-metal springs that expand or retract with hight . one sets the ring or lever, so the hand is equal to zero, on the beginning of the trip and then you see the rise or lowering in meters or feet at the end of your trip, that is the sense of it, but hard to say anything particular without pictures, Philipp

The more i know, the more i realize that i don't know enough.
812 310 121 S

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  • xjn001
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04 Sep 2012 23:15 #23416 by xjn001
Altimeter was created by xjn001
Can anyone tell me how the altimeter works? The needle moves with the change in weather , but what about the outer ring? Do you need to know the elevation? If so, where do you turn and set the outer dial? Thanks for any help.

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