The first part of the steam car which I plan to build will be the pumps. These consist of water, fuel, air and cylinder oil pumps. The air pump is a tiny thing, 1/4" bore, and its main function is to replace the tiny loss of air through absorption into the fuel in the fuel accumulator tank. However, an auxiliary air tank & hose could be added for inflating tires, etc, as the air pump will have some extra capacity. The fuel accumulator tank (now waiting in the shop) is an approximately 2 gallon tank with compressed air in the top and fuel in the bottom. It eliminates pressure pulses from the fuel pump and also stores a small amount of fuel under pressure to run the pilot light for an extended period of time and to fire up the boiler.
These four plunger-type pumps will be located in a small box near the water tank in the front of the car, below the radiator/condenser. A reciprocating rod will run from these pumps, under the car, to a lever-ended pivoting shaft, and thence, via a ball jointed rod, to a lever on the engine connected via link to one of the engine crossheads. Thus there are 5 moving parts in the entire pump system, not counting the pump check valves or the tiny separate plungers for the air and oil pumps. There will be no ball/roller bearings, gears, or cranks in the pump drive, saving money and fabrication time/effort.
Driving pumps this way has advantages, but it means that when the rear wheels go over road irregularities, the beginnings and ends of the pump strokes change position. So some extra room has to be left inside the pump cylinders, so that the pump plungers don't hit the ends of their cylinders. Ah, but exactly how much room? I had to know this exact dimension before I could finish designing the pumps and then build them.
With all the variables involved, this would be an extremely complex problem to solve through mathematical calculations, so I went ahead and built a full-sized wood-and-steel mockup of the engine, axle, rear wheels, pump drive system, engine hanger strap, and rear leaf springs. I also added a little indicator to simulate the end of one of the pump plungers, and a bracket to stop the engine pump lever at the ends of its stroke. All of this was fabricated, assembled, and mounted on a rigid framework to locate everything in the same relative positions they will occupy in the real steam car.
Then, on the fateful day of March 22nd, 2002, I finally completed the entire mockup system and did the motion tests. The tests consisted of simply moving the mockup wheels up and down, to various positions, and blocking them in those positions while I marked the plunger positions at beginning and end of stroke with the wheels in those positions. Due to interruptions, business matters, and ongoing design work, it took months to finish this mockup, but the tests took only about half an hour. I found that the plunger positions didn't change too much with maximum wheel/axle travel, and at last I had the elusive, critical final dimension for my pump design!
I wrote and sent in an article on my steam car project, and the mockup in particular, with photos, to The Steam Automobile Bulletin. The article and one photo were published in Volume 15, #4, pages 12-13. You can see the whole article by ordering this back issue from the Steam Automobile Club Of America (SACA) at http://www.steamautomobile.com.
The photo published in the article shows the engine/axle mockup mounted in the frame with the mockup springs, pump drive rod, etc, and I have several other photos which show the whole project completed. However, I do not have those photos in jpg format, so I cannot put those on this web page yet. In the mean time, a friend had scanned some earlier photos, showing just the engine/axle mockup without the frame, springs, pump drive, etc, at an earlier stage in the mockup project. I think that these were taken in the dark days of late 2001.
Here they are.
This is the mockup looking from what would be the front of the car toward the back. Note the rugged webbed axle housing geometry -- no "pumpkin" with flimsy axle tubes sticking out of it in my car! The actual axle will have chromoly tube truss bracing, running over and under the differential housing in the center and from one wheel to the other, all encased in bulletproof, superlight-weight aircraft-grade fiberglass/epoxy composite for strength and low unsprung weight. Pretty hi-tech, huh? Well, the front of the mockup is sitting on a flowerpot.
Here you can see the hump for the differential gear on the backside of the axle, to the left. This photo also gives an idea of how the long engine will prevent any twisting of the leaf springs by wheel torque. The engine itself acts as a decently long torque arm. With the extremely high level of torque (twisting force) which this engine will be capable of instantly producing at the rear wheels, this is a great advantage! The engine mockup is the large oval shaped tube extending forward from the axle, toward the right, which in the actual unit would be toward the front of the car. Thus this will be a mid-engined car. The mockup engine's oval shape represents the aluminum sheet-metal crankcase and cylinder block cover of the actual engine. Inside the crankcase are located the crossheads, connecting rods, valve drive mechanisms ("valve gear"), and crankshaft with main drive gear in its center. In the actual engine, the sheetmetal case will be entirely removeable in a few minutes with a screwdriver, leaving all the moving parts exposed for easy inspection and repair. Such repair should be as rare as transmission repairs in a modern gas car, once development work is complete, due to the extreme simplicity and ruggedness of this two-cylinder engine. Two cylinders, yet smoother-running than a V-8! And this type of engine has only 15 moving parts, whereas a V-8 with automatic transmission has nearly a hundred.
From the rear, in this rather grainy photo, you can almost make out the differential hump in the center of the axle, flanked by 4 small dots. These dots are the ends of the steel tubes which hold the engine mockup together. They mimic the 4 engine frame rods which link the engine cylinders at the far end of the engine to the axle. These rods also serve as the structural "backbone" of the engine, linking together the crossheads, main bearings, and other components. Like all engines, this one flexes under load; however, it is being designed to flex much more than most engines, as this flexible construction allows a much lighter weight and actually gives smoother running and some other advantages. The concept of a light, highly flexible "4-bar" automotive steam engine frame was pioneered by the Stanley Brothers, makers of the famous Stanley Steam Car (1897-1925), and was also used (in more rigid form) by Abner Doble in his famously powerful Model F steam car engines. In my engine, the bars will tend more toward the rigid side and will be made of 4140 Chromoly, a very strong and stress-resistant modern alloy.
As promised, here are more of the pictures. These are pretty self-explanatory, so I'll just drop them in for now. I may add commentary later. These are the complete mockup, including the frame, springs, valve drive, etc.. Pictures taken in March 2002. I have some more on the way, including a couple HUGE files that I think I'll put on their own pages (and drop links here); huge, but with incredible detail.
Okay, here are links to the HUGE files. You'll have to scroll around a lot to see the whole pictures, but you'll see every microscopic detail of the thing. I'm going to work out some smaller versions of these pictures, so you don't have to scroll all over the place to see them. In the mean time, this is the best I can do.
Pump Drive Rod, Levers, and Engine Hanger Strap
This one shows the working parts of the mockup, the really crucial stuff. To the left is the lever on the engine, then to the right the pump drive rod, and then the pump drive lever. In the real thing, there will be a rocking shaft extending toward the camera, from the pivot point of the rightmost lever, with a lever at its end extending downward close to the viewer, connected to the pump rod which runs forward to the pumps under the front hood. Note the little indicator wire extending to the right from the bottom of the drive lever. Hit back button to get back here and check out the next one.
Rear Fisheye View Of Completed Mockup Rig
This fisheye view is pretty distorted around the edges, but shows darn near everything inside the mockup frame. Have fun scrolling around! Hit your back button to get back here.
Don't know how this picture got crooked; must have been taken on a hillside.
This one is in living color! Here you can see the pump drive rod atop the engine.
Haven't got my inertial-propulsion antigravity backpack working yet, so I had to climb up on the perilous garage/shop roof to take this photo. This seems to be the only picture in computerable format which shows the little shelf for the test card, on the front of the mockup rig closest to the camera. A file card was tacked to this, and pencil marks were made next to the indicator wire at various suspension and pump lever positions. The indicator wire was attached to the bottom of the pump drive lever, and represented the position of the pump plungers.
Here is the rather modest first working part of my steam car, completed July 31st, 2003, being held by some unshaven character at wonderful Santos Cafe in the South Park village of San Diego. Unhand that steam car component, you scurvy knave! Who are you, and what have you done with Mr. Pete?
This is the frame which will hold together the pump unit of my steam car, and will take all the thrust loads involved in pumping. The hefty double-headed plunger water pump goes in the side of the frame with the wider rod spacing; in the narrower side go the single-plunger fuel, air, and oil pumps. The groovy polychrome color is an artifact of the celphonecam which took this picture; actual part is made of 3/8" cold-rolled steel plates with 3/8" threaded rods, not some gleaming far-out extraterrestrial hippie material as it might appear from this photo. At last, a step beyond the mockup stage. Now in progress: the working innards of the pump frame.
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