Back in the day…
Part of the maintenance of our steam locomotives includes the dead weight testing of our pressure gauges. This assures that our readings are correct and does not allow for assumptions in case something happens. On Monday Grump’s was in town to help out, and after warming up in the shop (it has been a bit like winter this week), and chewing some Iron Horse Manure with CMO Reader, set out to test and repair the gauges and the gauge tester. Phil picked up this fine bit of American Technology on Ebay last year. It is very complete and a testament to the excellent craftsmanship that is rarely seen today. It was made by Ashcroft.
After filling the reservoir and charging the pressure cylinder with a light weight mineral oil (sorry Castor Oil doesn’t work), the gauge to be tested is placed on the manifold. Then weights that correspond to the amount of pressure you want to check are added to the lift cylinder. You then screw the pressure cylinder clockwise until the weights are suspended on the lift. Rotate the weights slowly as they float on the lift cylinder and check your gauge to see if it is correct.
Here we see the gauge from the Harpur on the test stand with 120 pounds of weight on the lift cylinder which is suspended. The oil reservoir is on the right and the large screw is the charge cylinder. Well the gauge is a little off wouldn’t you say?
There are a couple ways of calibrating the gauges so they register correctly. Some you can access by removing the Bourdon Tube assembly from the case and adjusting the mechanism at the pivot fulcrum which has a set screw. On others you need to remove the needle and replace it back on the stem. This kit came with all the tools to adjust both of these types of gauges. On this particular one I removed the needle and replaced it so it reads correctly.
On the right of this gauge you see the needle puller and its case.
With the gauge re-calibrated it is then cleaned and polished and placed back on the locomotive ready for service once again. I really like this gauge. I found it on Ebay last year and paid only $35.00 plus shipping. What a deal!
Well after testing several steam and air gauges it was time for some maintenance on the dead weight tester itself. It has always leaked oil from the charge cylinder screw so it needed a new seal. When the old one was removed, it was shaped like a faucet washer, only this one was made from leather. In the cowboy shop Phil found a faucet washer set and I proceeded to combine two rubber washers and make a seal that fit and worked perfectly. Wow I should have done that first before I checked all those gauges!