I have this gauge posted in Antiquities , got most of my questions answered. The housing of this pressure vacuum gauge matches 1923-24 Packard. I can find no evidence of one on any Packard dash photo. The housing may have been used by other makes , or types of vehicle, Airplanes? The gauge looks like it has been in the housing since it was made. My only guess is supercharger , notice the 10 pound mark is 3/4 around the gauge. Retard means " dampen" in this case. No evidence of Packard having a supercharger in 23-24 Any ideas what else it could be used for? I posted at AACA forum , but not a lot interest.
Compound gauges are found all over fire trucks, but I cannot see a reason on a car for one other than an engine that has a charged intake. The pressure is in PSIG and the vacuum side is in inches of Mercury, which translates to about 1/2 of the psi. This gauge has an odd scale, 1to 5 inches of Mercury is quite large, 5 inches to 30 inches is real small. Kinda of odd. Bones
the meaning of "retard" when used on a gauge...from a patent... "The present invention relates to gauges and has special reference to retard gauges in which mechanism is employed to retard the movement of the gauge mechanism whenever the normal operating range of the gauge is exceeded."
With a max of 30 psig, the pressure is way too low for that gauge to be used on a fire truck pump unless a specialized piece of equipment and the gauge was on the intake side of the pump.
The compressed scale on a vacuum gauge is pretty common. Every refrigeration low side gauge is like that. I believe after about 5 in, the bourdon tube moves very little.
Yes I am familiar with that. One reason is that pressure is measured in psi and vacuum in inches of Mercury, 30 . That roughly translates to 14.7 PSIG …two for one! And that the same tube has to measure both, vacuum and pressure. The max vacuum you can obtain is about 29 inches, while on the A/C gauges the top pressure is something like 500 PSIG. What my observation was that the first 5 inches of Mercury was very large and the next 25 inches was compacted! Like five to one! Just wondering. I just now noticed the pressure gauge is like that! 0 to 10 even , over half the scale. Then the next 25 PSIG are very close. Must have something to do with the “ retard” feature Squirrel mentioned. Bones
Well, it never dawned on me that the spacing of the vacuum was approx. 2 for 1 with the pressure, due to the needle reaction stemming from the same (Bourdon) tube. They simply adjusted the spacing of the increments. Here's another example. Thank you for that explanation.
Now that one makes sense! The vacuum is about 1/2 the pressure on a 30/30 gauge and all measurements are uniform! This is a gauge I can understand! Thanks ! Bones
Well let me throw another thing at you! The specific gravity of Mercury is 13.6, roughly translates to one foot of water vs one inch of Mercury. These basic figures are handy in the field” guessing” what is going on with flowing/ pumping water. Ball park figures. This is why you cannot “ draw” water over about 28 feet . Just food for thought! That is another reason the folks back in the day decided to used Mercury to measure vacuum! The other is that it is liquid metal at common temperatures. PSIG for pressure and Inches of Mercury for vacuum. Wouldn’t be practical for a 30 foot column of water! Lol And the amount of vacuum you can produce varies greatly from Death Valley to Pikes Peak! And can vary somewhat from day to day in the same location! Bones
Thanks for all the education. Leads me to a lot of research. The first superchargers were designed roughly 1890. First production car with supercharger was Mercedes Benz-1920's All the boost gauges are laid out similar to this, only the scales differ. I believe the " Retard" feature is why it is compacted in the Usable scale range. Looks like it's definitely pre 1935 , most likely a housing at least shared by Packard. US gauge made gauges for anyone and anything. I'm calling it a 1920's supercharger boost gauge until someone can convince me otherwise. Any one up to the challenge?
Notice the super fine graduations in the pressure scale. Hardly useful when driving. I'll speculate that it was part of a piece of test equipment for measuring fuel pump output pressure. The vacuum section could be for distributor or wiper mechanism testing.
I agree, but most old gauges were precise and had thin pointed and balanced needles. Extremely accurate! Look at gauges today, most ninety degree sweep with an unbalanced needle about 1/4 inch thick! I have always been impressed with old gauges made in the USA! But, reading gauges was a way of life for me for 33 years+. In my shop , I had a tool for testing my test gauges, before I used them for testing. It was called a “ dead weight” tester. Bones
Yes, U.S. Gauge did make a variety of gauges for just about anything. And, they were high quality. Here's one that I sold to a HAMBer a while back to monitor his late 1930's McCulloch supercharger. I doubt that the gauge was specifically made for that, but its sure was a close period match. Ya gotta love it.
I thought about that , maybe a week ago. Very possible. Most Vacuum / Fuel pump gauges in modern era- 40's up, have a scale reverse of this one. Meaning vacuum 30 , pump pressure 0-10. It may have been for ' Laboratory" testing. The thing that confuses me is it's a match for 23-25 Packard instruments. As I stated many posts back , the housing could have been shared with others. I would guess Packard didn't make their own housings or instruments. Thanks for all the feed back, about 10 times what I got at AACA / Packard forum.
You'll be sleeping peacefully about midnight Sunday when it hits you. Don't be like me and wake the wife up to tell her all about it. Just saying
I don’t have the answer to this interesting question, but perhaps I can add value to the search. Gauges like the one in question are called compound gauges and are typically used on the intake side of a pump. In Boneyard51’s example, think of a water pump: it can add pressure to it’s pressurized source (fire pump drawing from a hydrant), or even create enough pressure on its own to pull a vacuum on the source (not the best thing for the local water supply when a fire pump over does this!). So, what could the interesting gauge have been used for? Wow, I truly don’t know, but It was most likely for a system that can pull more pressure than it’s source provides. Have at it…. John
Could it be from a Packard dealership test rig? Hard to believe they'd bother matching the car styling, but then Packard was a pretty high class operation in those days.
It could have been used as a fuel pressure gauge on the downstream side of the fuel pump (assuming they in fact had a fuel pump) or fuel filter. Pressure would indicate fuel passing the pump and/or filter in excess of the engine demand and vacuum would indicate a failing pump or a clogged fuel filter. I got that idea after looking at a fuel pump test gauge I have for an OT diesel. John
Thanks for the input guys. Keep up the feedback. I no longer own this gauge, but I'm still curious about it.
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