Detroit Hydrostatic Lubricator

Thanks for the tip. I checked Model Engineer and back issues are currently unavailable. The ME web pages says try again in a few weeks.

Dave

Hi Dave

Glad you found the Proboards site ok, it is more locomotive orientated than this forum, and thanks to Duncan for posting the link to the lubricator drawings I had not seen those. Please do keep us updated on your progress and findings, a few more pictures of your locomotive would be appreciated too, some lovely workmanship there and an interesting prototype.

Keep up the good work I look forward to seeing it progress.

Dave

It has been about a year since my last progress report. First off: Where does the time go? Well, in the case of my hydrostatic lubricator project I've made considerable progress. Keeping mind that it is an integrated system from the cab to the cylinders. I finished the cylinders. Photos are in my photo album. I made the steam chest cover same as the prototype with a balanced slide valve there is a port running fore and aft that drips the oil into each end of the steam chest over the steam ports. Rising out of the top center of the steam chest cover through the decorative safety tread cap is the oil feed line than angles upward then into the smoke box casing. On the 1893 prototype the smoke box was lagged/insulated then cased with Russia Iron. That was not practical for my model so a solid tube was machined for the smoke box with a 1/4" wall. A hole was drilled from the rear of the smoke box to intersect with the tube fitting. In the photo a brass screw can be seen threaded into the rear of the smoke box where the oil tube from the cab will enter. The boiler is a smaller diameter than the smoke box so will enter the rear of the smoke box and the oil tube pass along the outside of the boiler under the casing. So the cylinders are complete. What do you think. Will my oil system function?

As a result of our previous posts, I have also been working on the lubricator. The photo shows the first solid model 3d printed iteration. The first lost wax casting of the condenser showed that the investment could not completely be removed from the condenser cavity. This has forced me to split the condenser and reservoir into upper and lower halves so they can be thoroughly cleaned. Two vertical tubes also have to added to the lower reservoir half to feed the oil to the sight glasses. I have the waxes printed for all four castings and will send them out for casting in brass this week. If anyone has an interest in the configuration of the waxes let me know and I'll post pictures.

I have to admit I'm still perplexed about whether to or not have steam fed to the top of the sight glass to force the oil to the steam chest. I'll be using a 1/8" brass tube with a .015" wall from the lubricator to the cylinders. It is almost 30 inches of tube which seems like a long way without some steam to push the oil along.

Thanks for reading, Dave

That's some fine work Dave, going to be a fantastic locomotive. I could very well be wrong but I don't think a separate steam feed to the top of the sight glass would work, my understanding is the condensed steam at boiler pressure displaces the oil and the pressure difference between the boiler pressure at the oil tank and steam chest pressure causes the oil to be carried to the steam chest. I would have thought that applying a steam feed to the top of the sight glass would equalise the pressure across the system causing it to stop feeding. I know of a 71/4" Highlander that was fitted with the system as described in the Julian Atkins articles and I know that fed reliably with just small bore pipes to the cylinders (twin sight feed) with a restrictor where it entered the steam chest, my only input was to make the sight glass. I would think the length of delivery pipe would be similar to yours. That was years ago, but saw it for sale a couple of years ago still fitted with the system so must still be working ok.

I'm sure if I have it all wrong someone will be along to correct it!

Dave

Good to hear from you again Dave. Thanks for taking the time to reply.

According to the documents I have found for full sized lubricators the steam feed to the top of the sight glass kept the whole lubricator under "near" equal pressure, with a slight pressure drop at the top of the sight glass. There was a choke placed in the sight glass delivery tube and another at the steam chest. The pressure from the height of the equivalent water column is what pushed the oil through the feed adjusting valve at the base of the sight glass. My lubricator as currently designed is approximately 3 1/2" tall. Add 1/2" to the top for fittings for a total of a 4" water column. The question then is how long of a water column is needed? I have no idea!

I'm building the lubricator so that can be fitted with or without steam feed to the top of the sight glass. I'll experiment with both and see what works best or at least if I can make either work. The results could be interesting. I'll keep records and post the results. Given my rate of progress that will probably take another year.

Dave

GWR locos had a condenser coil in the cab roof so that the length of pipe down to the lubricator filled up with water which added to the pressure pushing the oil through

Edited By duncan webster on 25/05/2023 11:26:03

Hi Dave

You have obviously researched this well, I was not aware that full size lubricators worked in that way, wrongly assuming it was all down to pressure differential, must admit that I never gave the effects of gravity a thought.Very Good idea to make the steam feed optional, and it would be great if you made your results known, I've learned a bit more already! Look forward to seeing some more pictures of your progress, judging by the quality of the work so far it's going to be some locomotive!

And Duncan's point about mounting the GWR condensers in the roof had also never occurred to me, but makes perfect sense, you can learn a lot on this forum!

Dave