I have an interesting gauge I'll be attempting to restore/repair for MEC 470. I have not been able to find much of anything about it….
It is an Ashcroft Locomotive Cutoff Control Gauge. It has two needles, red & black. I have a few questions about it and hope one of you have some experience with one of these. First, do the needles both travel clockwise with pressure? As it now is, the red needle has no return action. The black needle is fully clockwise against the 400psi stop with spring action pulling it towards the stop. I think this should be at zero and able to register into the vacuum range. I have not yet pulled the needles and face to get a good look at the mechanics. There are two separate bourdon tubes. The base bronze casting has what I initially thought were the option to connect the steam lines to either the top or bottom of the gauge. The “plugs” in the bottom fittings are drilled and wired together with a crimped lead seal. That makes me think it might be an adjustment of some sort but have no idea. I'd think a typical pipe plug would be used if it was just to plug an unused port.
I looked in the two Locomotive Cyclopedias I have, 1930 & 1940 without finding a gauge like this. Mostly Ashton stuff. Not much luck with internet searches either….
Anyone have any insight?
Thanks,
Bob
New England Steam Corp.

In general, pressure and compound (pressure/vacuum) gauges move clockwise with pressure.

There is no "return spring." When the pressure is zero (atmospheric), the Bourdon tube will be in a certain position, and the hand will track that position via the link, sector, and pinion. Application of pressure causes the Bourdon tube to deflect, and that moves the needle.

If you grab the needle (assuming the hand is not resting against a stop pin) you'll be able to deflect it both ways and it will "spring" back to the correct pressure, but that is because of the inherent springiness of the Bourdon tube.

The hairspring attached to the needle shaft/pinion generally moves the needle clockwise. That is not a return spring, but a very light spring to take up the lost motion in the mechanism and ensure that the reading is the same when pressure is going up versus going down.

If the hands are resting at an absurd position with no pressure, that could be due to a number of things, including previous repair attempts. It's also possible that the Bourdon tube is damaged internally, e.g. because the siphon tube was totally filled with water and it froze.

Remove the two hands carefully using an actual needle jack (not a pair of screwdrivers or other such butcher's tools) and take the dial off, and the cause of things should be much clearer!

I'm also a bit puzzled by the dial layout. The hash marks are 5 lb increments from 0 to 400psi. The writing on the dial states “difference between hands exhaust pipe pressure each mark=1 lb”

Does the patent help?

https://ppubs.uspto.gov/api/pdf/downloadPdf/1664776?requestToken=eyJzdWIiOiI3NGFkNWZlNS1kNTQxLTQ1YTMtODUyMS1kYTdjNDA0NjgyZmQiLCJ2ZXIiOiIxMTYzNjU2MS1iNTI2LTQ5NDktYjY1ZC04YTY1YmY0MGQyNzUiLCJleHAiOjB9

I did come across that patent. Not really for the gauge itself but for the non vibrating needle mechanism.
Thanks for posting the link.

This should be a big help! Need to read thru it all and digest…
Thanks much!

After looking at the documents that were posted in the thread, I believe you'll find that there are two tubes in the gauge. One, connected to the steam pressure pipe, has links to both hands. The black hand will have a single adjusting slide of the usual type which sets the "span" or degrees of hand travel per pound of pressure. The second tube, connected to the exhaust pipe, most likely has a link which connects to the red hand only, using a mechanism which opposes the travel of the other tube., such as a floating lever. The mechanism can be proportioned in such a way that the differential of 1 pound causes the same hand movement as 5 pounds of pressure.

All will become apparent if you open the gauge!

Anxious to get into it. Unfortunately none of my three needle pullers will fit the massive needles…. They are 1/8” thick. Kinda funny that the Patent number refers to anti vibration needle movement but the gauge documents state the gauge requires vibration to operate properly and is only good for moving locomotives and must be continually rapped while calibrating.
There are two bourdon tubes, one is twice the size of the other.

I modified one of my needle pullers to properly fit the large hands of this gauge. They removed easily without much fight. Three screws held the dial face in place. Finally got my first good look into the innards. It doesn't look good for successful operation. The red needle pinion and rack are not engaged with each other. Poking about I soon realized the larger bourdon tube is distended and the moveable end of it is against the case. I would think the tube profile would be similar to the smaller one. Either freeze damage or over pressurized.
There are four adjustment screws for the mechanism. A “window” made in the base to access one of them is nowhere near providing a shot to the screw. Another indication of the tweaked bourdon, if you pull it in the screw moves towards its access hole.
Guess it'll be a display piece or parts for another….

I believe this is an internal plan of the same gauge, it says Milwaukee Road but not who manufactured it, but if you look at the details at the bottom the print and numbers are the same ("difference between" can be seen): https://www.lakestatesarchive.org/Drawi ... /i-r9HF7xJ

I found one that sold at an auction: https://auctions.morphyauctions.com/STE ... 57991.aspx

An interesting project, it would be neat if you could reverse engineer the missing parts.

Thanks PMC!
The drawing does answer a few things. One, it names the drain plugs at the bottom. I wasn't sure exactly what they were.
It also shows the profiles of the two Bourdon tubes and the large one is a fatter profile.
I'm not missing any parts. The primary issue is the large Bourdon tube is distorted and sprung out to the case lip. I'm guessing freeze damage. Don't think there is any fixing that at least by me. Since Ashcroft is still in business I'm going to contact them and see if they can fix it. Not very hopeful they will. No mention of vintage gauge repair on their web site.

There is an Ashcroft catalog from 1920 here: https://www.google.com/books/edition/As ... frontcover

Your gauge isn't in it, but what I notice is how common similar Bourdon tubes are in those gauges, it may be an off-the-shelf thing.

There is a guy who goes by Ashton on Smokstak who is the great-grandson of the founder of the Ashton Steam Gauge company (a different company from Ashcroft) who posts stuff about steam gauges occasionally: https://www.smokstak.com/forum/threads/ ... ge.187144/

It looks like Ashcroft wants you to throw away your used modern gauges and buy new ones, big surprise, but this statement also implies that they have parts available for older ones, so good luck: https://www.ashcroft.com/wp-content/upl ... pi-61c.pdf

Here's another: https://blog.ashcroft.com/are-pressure- ... repairable

After digging for a long period, I found the contact for technical experts about repairs: https://sales.ashcroft.com/contact-us-question

He has posted here with a lot of information as well.

https://www.rypn.org/forums/viewtopic.php?f=1&t=43684&hilit=ashton&sid=64a84c7798ed0eca98cab9786e01a465

Last visited Thu Apr 03, 2025 9:19 am, but he may be notified if you PM him. In that thread is a link to a company in the UK whom he says will repair steam gauges: http://viewer.zmags.com/publication/6fd ... 6fdab368/1