JV Puleo

My 1910 Mitchell "parts car" project

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Posted (edited)
On 3/15/2019 at 9:07 AM, Frank Tate said:

I am not an engineer by any stretch of the imagination, so please take this with a large grain of salt.  Rather than a coil spring, would it be easier to put some sort of leaf spring under the vanes?


Originally, that is exactly what I had intended. There are one or two complications. First, is finding a spring that can be relied on to survive the huge number of cycles the spinning pump will produce. If a flat spring broke, and the two pieces ended up on top of each other, this could stop the vane from being able to retract far enough thus badly jamming - and I suspect wrecking, the pump. I'm thinking coil springs would be safer since if one of those broke most likely the pieces would remain in the holes... though I'm not entirely satisfied with that idea. Hence my plan to test the pump without any springs at all.

Edited by JV Puleo (see edit history)
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Could you bore a hole lengthwise in the vane and fill it with lead.  Would the added weight be enough to ensure that the vane followed the contour of the body tightly?

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Posted (edited)

The vanes are only slightly more than 1/2" tall and 1/4" thick. If I drilled a hole through them and filled it with lead - which might be a lot more difficult than it sounds, I doubt the difference in weight would be significant. I think that making a fixture and drilling holes for coil springs - for that I could probably get some springs that are actually made for vane pumps - might be easier.

 

This is a rare situation where a small, precise drill press or mill would be an advantage but I recoil at buying another machine to do just one job.

Edited by JV Puleo (see edit history)
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I understand you want to make all the parts yourself for this project, but have you considered making a housing for a gerotor/trocoid type oil pump that you canibilized from a modern car/motorcycle? With the considerable effort that you have put into this project, would the peace of mind of having a proper pump hidden inside a housing that you fabricated be more acceptable to something that you are not 100% will work for at least 10,000 miles or more? I am not a fan of vane type oil pumps for any application especially for the “heart” of an engine.

I am not posting this to throw stones at you, only to see that you are successful at realizing your vision of a completed project that can be driven without worrying that the oil pump is supplying enough oil to the parts that are made out of unobtainium.

Jim

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Posted (edited)

If it doesn't work I would certainly consider that path but part of my goal is to do everything using the technology readily available during the working life of the car which, I tend to think of as 1910 to 1915. I don't claim to have entirely succeeded, at least in that the some of the materials I've used don't fit that criteria and a few of my machines are a bit newer. That said, the reason behind all the testing is that I want to run the pump, and eventually the entire oiling system, off the car for a considerable time before it is assembled on the engine. This is probably the most critical element of the engine work since everything else is relatively uninnovative.

 

My primary engineering text is the 1910/1912 edition P.M. Heldt's The Gasoline Automobile. There are elements I've stretched the logic on - the use of aluminum pistons is something Heldt didn't mention but I know that W.O. Betley was using them in his DFP racing cars before 1914. The same can be said for aluminum connecting rods which were at the very beginning of their development during WWI and don't really start to be adopted until after the war and then only in an experimental sense. Some of my diversions from the goal are simply dictated by what I can make with the machines I have.

 

There is more to the oiling system than I've mentioned so far. In addition to the vane pump, I'm designing a small hand pump to incorporate in the system that will allow me to pump up oil pressure before the engine is started. I'm not yet sure how that will work but it might give me a margin of safety should the vane pump fail in use...maybe. It is just the concerns you mention that make me want to test the system without the springs. The basic pump is an extremely simple device. If it works as it is, it will be practically indestructible as long as there is oil in it.

Edited by JV Puleo (see edit history)
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Thank you for your response. Was there a reason you opted for a vane pump verses a gear pump? My experience with old cars only goes back to the mid 20’S cars, and have never seen a vane type pump in any application, only gear.

Jim

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Posted (edited)

Vane pumps were invented in the 1870s and are described and illustrated in Heldt's book. He mentions their occasional use for both oil and water. The Mercer used a simplified version of the vane pump for oil. I chose to use one for two reasons... they are self-priming and whatever pump I use has to be able to pull oil up from the sump because the pump is located on the back of the engine. That location was determined by the need to have some means of driving the pump.

 

The original system was a semi-total loss with an oiler on the side of the engine, belt driven from the front pulley. There is no built-in drive for an oil pump and, in any case, I am trying not to make any permanent modifications to the original parts of the engine. The only place I could think of to put the pump was on the back of the camshaft taking the place of the rear camshaft bearing holder. In putting the pump there, there are serious size limits because it fits inside the front rim of the flywheel.

 

I also thought of making a pump that could be driven by the water pump/magneto shaft but that would have had to be self-priming as well. There was no way I could think of locating a gear pump low enough on the engine so that it did not have to pull oil up from the sump. I actually started out with a gear pump design and have designed both gear and plunger pumps for this application – neither of which were anywhere as near and simple as this pump.

Edited by JV Puleo (see edit history)
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Chevy stovebolt 6's from 29' up to the mid thirties used a vane pump as standard. Have always had no issue with the vane pumps. The Chevy wasn't pressurized so the pump's operation was to flow oil to the troughs for the dippers, the center main bearing, the rocker shafts, and to spray on the timing gears. At temp oil pressure was often 10-12psi. 

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I have been struggling away with the oil pump. This is probably the most precise thing I've ever made and getting it right is proving a challenge. I finally got the rotor in and I've lapped the vanes so that they slide by gravity with no noticeable side-to-side play.

 

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I then put it together and discovered that it binds slightly when the cap screws were tightened down - but not when they were slightly loose. It took me nearly all day to figure this one out but now I think I've got it. It looks as if the small end center shaft - that takes the place of the camshaft - is very slightly off center. I'll make another one tomorrow but in the meantime, I did get it so that it turns with only a hint of binding. With luck, I may be able to assemble it and test it tomorrow although first I'll have to buy a gallon of cheap motor oil because I don't want to use the abrasive stuff I used the first time.

 

IMG_1236.thumb.JPG.f853c1f733db3ca17389cda90561540d.JPG

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JV, I see that you are using the 1910-1912 edition of Heldt's work as a guide to materials. It may please you to hear that in the 1916 (5th) edition he goes into considerable detail on  the use of Aluminium pistons.

 

'Aluminium Pistons. - High speed engines are often fitted with pistons cast of aluminium alloy......'  page 161.

 

So it appears that you are not too far ahead of the times, if at all, in using aluminium.

 

I'm finding Heldt's work fascinating reading. I must thank you for recommending it in an earlier post . Keep up the good work, as there are many of us lurkers out here following it, I am sure.

 

 

 

 

 

 

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I have a lot of respect for Heldt. He appears to have stayed right on top of current developments but I'm surprised he knew about aluminum pistons in 1916... that's really interesting because in 1914, at the beginning of WWI. W.O. Bentley showed them to the Admiralty - he'd been using them in his racing cars but until then he'd kept it secret. The Admiralty was so impressed that they commissioned him into the Navy as a Lt. and assigned him to aircraft engine design. As he tells the story, he left that morning to see Admiral Hall and came back as a naval officer.

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Well...I put it together and tried it. It looks as if I'll have to incorporate the springs. It did draw up some oil but not enough, or fast enough, to be satisfactory.

I am going to take it apart again on the test stand to see if the blades are actually moving - they may not be. Getting the right fit and finish is proving to be a real challenge.

 

jp

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I'm so surprised when something of mine works the first time I usually take it apart anyway just because I can't believe it.  I'm sure your pump will be pumping just fine very soon.

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I'm not surprised it didn't work though I didn't anticipate the reason. One of the things I did this morning was polishing the vanes. I did that with a piece of 500 grit wet or dry using the lapping plate as the flat surface.

 

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The result was quite satisfactory. The vanes fell into place from gravity alone.

I then assembled the pump and ran it - to no avail. It did pull up a little oil but not enough to reach the pump. I then took the end plate off but left it on the stand so I could easily rotate it and see what was happening.

 

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It turns out that the surface tension of the oil is enough to keep the vanes from sliding out. Aside from that, I suspect it will work brilliantly. In fact, it was drawing weakly without the vanes doing anything at all which I take to be a very good sign. The pump is also turning very smoothly. So, now I have to design a fixture to hold the vanes while I drill holes in them for little springs. This is actually a real challenge for me because the fixture will have to be extremely precise. There is very little room to work with and since the vanes were made on the rotor, replacing them could be a major undertaking. I'll have to make the fixture and make a few test vanes to set it up so that when I do make the holes I'm confident they will be in the right place and the right depth. I'd also like to find some real vane pump springs 1/8" in diameter and about 1/2" long. I don 't know if that is realistic...for the moment I'll get something from McMaster Carr but I'm concerned about the huge number of cycles these springs will have to sustain. One potential problem is that the pump itself will be inaccessible when the engine is assembled. To get to it, I'd have to take the engine out and remove the flywheel. Thankfully, that isn't a big deal on a brass car but it isn't the sort of repair you can do on the side of the road.

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Persistence is always good.  I think if you do a google search for modern vane pumps and do a bit of sleuthing around you would locate something modern with the same vane width as you have built then buy a set of replacement springs.  When ever I rebuilt vane pumps in the past, the kit always came with replacement fiber vanes and a full set of springs.  Our vane pumps rand wide open, 24/7 for 3-4 years between rebuilds.  That is a bunch of run time your pump will never see!  (At least I am guessing). 

Al

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I think you are right there even if I drive the heck out of it - providing I finish it before I'm too old to drive!

I'll get on that tonight.

jp

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If it were rotating faster, would the vanes go outward under centrifugal force?

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Posted (edited)

Maybe, but the speed I'm running the tests at is probably close to a comfortable cruising speed. As it is,  it wouldn't pump oil at idle or even slow speeds. But, I had springs behind the earlier vanes and that pump worked so I am certain this one will. Tomorrow I'll start on a fixture to drill the holes...I've been giving it some thought and I think I can make one that will do the job.

 

Edited by JV Puleo (see edit history)
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Posted (edited)

Setting up to drill holes for the little springs is taking some time since as I've noted before, I'm not really equipped to make fiddly little parts. I need a drill press that has some means of controlling the downward travel of the quill and, unfortunately, the only machine I have is this small antique... probably the first machine I bought for this shop. I paid $25 for it on the local CL. When I got it back to the shop (I bought it in the dark) I discovered that the taper in the quill was really messed up. I "sort of" fixed that a long time ago but it still runs out about .005. Oddly enough, in this case, that might be a good thing. Yesterday I faced off the table. It is full of divots from sloppy workmen in the past and perhaps I should fix that someday but for now, I just wanted to be confident it was flat.

 

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The next step was to make a sliding stop to fit on the quill. I've wanted to do this for a long time but all my ideas were over complicated.  I finally thought of a simple way to do it but marvel that it took me so long to come up with an idea.

 

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Here it is clamped on the quill. I used two of the nylon tipped set screws to hold it in place so they don't put a burr in the bronze quill.

 

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Tomorrow I'll start on the holding fixture. Then I have to make another set of vanes - not to use but to test the setup with. I do not want to try drilling the actual vanes until I'm certain the technique will work.

Edited by JV Puleo (see edit history)
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The holding fixture for the vanes...

 

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The groove is a little tight. The vanes are actually .258 thick and fitted to the slots in the rotor. I would have liked to use the same cutter for the fixture but getting the 1/8" hole exactly in the center of the groove may have been a problem. I used an end mill to make the slot in the fixture but drilled the hole first - both operations were done without removing the piece from the vise. The big hole is for a 3/8 cap screw to hold the fixture down. I may even drill and tap a hole in the drill press table - something I'd never do were it not that it's full of holes already. The small hole is to locate the end mill directly in the center of the vane.

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3 hours ago, alsfarms said:

Very Crafty

 

It is indeed though I believe it could be seen as cheating.  A real mechanic would eye-ball that with a hand held drill in one hand, the vane in the other while walking through a shop lit by a single light bulb.  (I would mention that the bit would be bent and dull but I think that's obvious) ;)

 

I hope that reading about Joe's patience will somehow rub off on me. 

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Isn't he supposed to be chewing on the stub of an unlit cigar while doing this?

Actually, I've never claimed to be a real mechanic. The fact is, I tend to think up complicated ways of doing simple things. If I were doing it for a living I'd be in trouble.

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8 hours ago, JV Puleo said:

Isn't he supposed to be chewing on the stub of an unlit cigar while doing this?

Actually, I've never claimed to be a real mechanic. The fact is, I tend to think up complicated ways of doing simple things. If I were doing it for a living I'd be in trouble.

 

Yes, though the cigar should be lit if he's also spraying clear coat at the same time. :)

 

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Posted (edited)

Joe, your approach will pay off in the end, you will have removed small variances or issues from the equation (your oil pump) and the result will ultimately spell success.

Al

Edited by alsfarms
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