This image is from page 152 of Thurston’s, “A Manual of the Steam-Engine”, Vol 1, 1903. I thought a few might find it of interest. It is certainly one way to eliminate the cross head. Though, I suspect it only ended up saving about half the lenght of standard DA layout do to the length of the con rod. According to the text, this engine was built several years before the publication of Thruston’s book. The engine was designed to run a small electric generator. It also mentions this engine ran for years at 1250 RPM. Garryhttp://steamautomobile.com/phorum5214/read.php?1,4310,4310#msg-4310Thu, 09 Sep 2010 15:25:57 -0500 Phorum 5.2.14 http://steamautomobile.com/phorum5214/read.php?1,4310,4374#msg-4374 http://steamautomobile.com/phorum5214/read.php?1,4310,4374#msg-4374Some where among this stuff, I have a really old xerox of another unusual engine Ericsson designed. I believe it is from a biography written a couple years after his death. (I was only the third person to check the book out in the seventy years the library had owned it!) This engine was a really strange one Ericsson did for the US Navy. Basically, it was a cylinder divided into three compartments. Each compartment contained what looked like the guts out of an over grown vacuum windshield wiper motor. If memory serves me, each section was mounted to an individual shaft near the center of the cylinder, and each had its own lever attached to its own shaft. The ends of each lever were connected to links leading to a single throw on the crankshaft. I think the crank may have been mounted under the cylinder, but I haven’t looked at this in over thirty years. The engine was actually installed in a Navy vessel, but they had real trouble maintaining the seals on those long flat oscillating plates. Off hand, I don’t remember how the valving was arranged.

Jim
I have ran across a trunk engine like this before. I just did not like how much longer the trunk end inlet valve had to be open to balance out the power on each end of the cylinder in a simple engine. Why it never occurred to me to look at this as a compound is a bit of a wonder to me.

I don’t believe the single inlet valve uniflow would be as efficient as running valves on both ends of the cylinder, do to the transfer port space acting as part of the clearance volume on the low pressure side. Though, the simplicity of the basic single inlet design would save considerable machining costs.

My guts says going to a uniflow on this design would be worth while, in that it would help isolate the temperature differences on each end of the piston. Then, I guess you could always reheat the steam from the high pressure exhaust. And then, you get the fun of figuring out what to do with all that excess heat coming out the low pressure side. Hmm... Then if you did use reheat, perhaps you could stretch the expansion ratio of both the high and low pressure sides? I keep this line of reasoning up, and I am going to end up spending way too much time with the calculator. :)

I like the idea of using a water drain on the ‘trunk’ seal. You might want to add a double lip wiper seal in the packing cap to help keep the water from running into the crankcase oil. I think you are right about needing rings and packing on the trunk of this beast. Even then, you might as well go ahead and run a steam exhaust line through the oil pan to make sure you didn’t end up with the frothing grey goos blowing out every where. Even if the frothing goo were not a problem, it should end the need of having to drain what did collect in the crankcase, and the possible corrosion, in more conventional designs.

The three cylinder inline would probably be the simplest to build. Though, myself, I do like the compact length of a V4. It leaves more room for the steam generator. In steam though, it looks to me like a 90 degree V is the only practical way to go without adding crank throws for each cylinder, and you have even more complication in the valve gear. Then I haven’t looked at V configurations in so long, I have more than a bit of reeducation to do.

Well, before I give myself brain lock again...
Garry
PS: After writing all of this, it occurred to me you would have to have separate exhaust ports for each end of the piston on a compound uniflow for a trunk piston engine. Talk about a really long piston! Well, back to the drawing board! A simple conventional hollow transfer piston valve most likely. Dang, but such brain farts are annoying...]]> Garry Hunsaker SteamStuffWed, 13 Oct 2004 22:10:01 -0500 http://steamautomobile.com/phorum5214/read.php?1,4310,4365#msg-4365 http://steamautomobile.com/phorum5214/read.php?1,4310,4365#msg-4365
Interesting stuff on the Ericsson Monitor engine
[www.pcez.com]

This one claims that Watt invented the trunk engine
[www.du.edu]

I have an old book that shows such and engine being used to run an air pump on a jet condenser, and also a boiler feed pump, all in one relatively compact unit. The valveing for the engine was done by corliss type valves.
If I remember I will try to get a scan of the drawing.


Andre' B. Clear Lake, Wi.

]]> Andre' Blanchard SteamStuffWed, 13 Oct 2004 11:29:32 -0500 http://steamautomobile.com/phorum5214/read.php?1,4310,4362#msg-4362 http://steamautomobile.com/phorum5214/read.php?1,4310,4362#msg-4362My interest in this configuration was because of the great difficulty in packaging a double acting engine with the usual crossheads into a modern chassis like the C-4 Corvette. You just can't get a 4"-5" stroke engine in there.
Also my interest in the Wankel, for the same reason, although there are several serious thermal problems with the Wankel that cause lots of concern.

Making it a unaflow means that you would have to make the piston longer to cover a unaflow port for the HP side and keep it isolated from the unaflow port for the LP side, a matter of only an inch or two.
With a three cylinder unaflow, there is no reason you couldn't make it with porting and crossover manifolds that would lessen the number of valves. Just such and engine was designed and built during the clean air car work, it only needed the three inlet valves.

The large diameter "crosshead" would easily carry a couple of piston rings and a packing gland on the outside to keep water out of the crankcase. Probably with a drain line next to the packing gland to also help keep water out.

The wrist pin can be towards the end of the HP piston so you don't have to use such long connecting rods, although mechanically they do help.
All in all, it is one interesting way to make a double acting engine that is a lot more compact than the usual crosshead type and worthy of some study.
JC]]> Jim Crank SteamStuffWed, 13 Oct 2004 09:37:05 -0500 http://steamautomobile.com/phorum5214/read.php?1,4310,4360#msg-4360 http://steamautomobile.com/phorum5214/read.php?1,4310,4360#msg-4360
But from what I have heard here. Modern packing meterials are available that need little or no adjustment once seated in.

Andy]]> Andy SteamStuffWed, 13 Oct 2004 08:15:44 -0500 http://steamautomobile.com/phorum5214/read.php?1,4310,4353#msg-4353 http://steamautomobile.com/phorum5214/read.php?1,4310,4353#msg-4353
I was considering using the packing seal external to the piston in much the usual way, but directly onto the piston instead of a connecting rod. This, I would think, would make a very effective seal espesially on the high pressure,smaller diameter, first stage piston of a compound engine. Perhaps even combined with one piston ring.

What I'm wondering about is the relative amount of wear and friction produced compaired to a piston ring.

Also some of the newer packing materials can take quite high temperatures compaired to graphite and the coefficient of friction is about the same.

Thank you---------------Bill G.]]> Bill Gatlin SteamStuffTue, 12 Oct 2004 20:21:03 -0500 http://steamautomobile.com/phorum5214/read.php?1,4310,4351#msg-4351 http://steamautomobile.com/phorum5214/read.php?1,4310,4351#msg-4351
Bill, with modern packing materials, I have wondered about using it in place of standard metal rings, but how would you go about maintaining the seal as the material wore down? An expasion ring under the graphite?
Garry]]> Garry Hunsaker SteamStuffTue, 12 Oct 2004 17:42:59 -0500 http://steamautomobile.com/phorum5214/read.php?1,4310,4334#msg-4334 http://steamautomobile.com/phorum5214/read.php?1,4310,4334#msg-4334
It looks like with this configuration the upper piston end is going through a cylinder and being sealed with packing. Isn't this out of proportion to a standard piston with the piston rod itself being sealed with packing? (bigger circumferense to piston diameter)

For instance in this case would an internally (mounted in the cylinder) or an externally (mounted on the piston) piston ring produce a better seal or less friction.

Given a design situation like this, what are some of the trade offs between using rings vs packing?

Thanks everyone------------------Bill G.]]> Bill Gatlin SteamStuffMon, 11 Oct 2004 21:10:55 -0500 http://steamautomobile.com/phorum5214/read.php?1,4310,4322#msg-4322 http://steamautomobile.com/phorum5214/read.php?1,4310,4322#msg-4322In an ancient book on steam engines I have in my library there are two very interesting descriptions of exactly this type of construction.
One is a compound steam engine, using the crank end bore as the HP and the head end as the LP. Also a cross compound version.
The second was a two stage air compressor, using the same idea.
The steam engine used a ball at the wrist pin end of the connecting rod, just like the naptha launch engine.
Why not?
JC]]> Jim Crank SteamStuffMon, 11 Oct 2004 08:38:58 -0500 http://steamautomobile.com/phorum5214/read.php?1,4310,4317#msg-4317 http://steamautomobile.com/phorum5214/read.php?1,4310,4317#msg-4317 Ben in Maine SteamStuffSun, 10 Oct 2004 06:41:05 -0500 http://steamautomobile.com/phorum5214/read.php?1,4310,4315#msg-4315 http://steamautomobile.com/phorum5214/read.php?1,4310,4315#msg-4315
I did a quick search for Henry; there’s not much on the web. Then, most of history is written by attorneys about financiers, and others that still believe the illusion of power mandates an even more illusionary form of security. For my money, it is the engineers that have applied research to the real world that has shaped the reality we see today. And, they danged well deserve a lot more credit than they generally receive.

Any idea as to what time frame Henry Stickney was doing all of his work? It would help to narrow down the search for info on his creations.

By the way, are those really good photos, or really good potatoes, that Fred occasionally has? I am not certain which would go better with breakfast.
Smiles
Garry]]> Garry Hunsaker SteamStuffSun, 10 Oct 2004 05:52:33 -0500 http://steamautomobile.com/phorum5214/read.php?1,4310,4314#msg-4314 http://steamautomobile.com/phorum5214/read.php?1,4310,4314#msg-4314 Ben in Maine SteamStuffSat, 09 Oct 2004 17:25:10 -0500 http://steamautomobile.com/phorum5214/read.php?1,4310,4310#msg-4310 http://steamautomobile.com/phorum5214/read.php?1,4310,4310#msg-4310
According to the text, this engine was built several years before the publication of Thruston’s book. The engine was designed to run a small electric generator. It also mentions this engine ran for years at 1250 RPM.
Garry]]> Garry Hunsaker SteamStuffSat, 09 Oct 2004 13:18:06 -0500