Southern California Home Shop Machinists
By Jerry Brown
It is with regret we announce the passing of Jerry Brown on February 2012.
Obituary for Jerry Brown 1930-2012
To see many more details about Jerry's Miniature Live Steam Shovel, visit this interesting website:
Here in Jerry's own words is his story about the creation of this amazing working model:
Miniature Live Steam Crane
My interest in power shovels and cranes goes back at least as far as I can remember. While more "normal" people were watching sports, I would be happier looking at these things. Their operators seemed no less skillful than ball players, and what they were doing seemed much more useful.
Revolving shovels, with their various mechanisms working in concert, have a measure of balance and coordination matched by few other machines - a symphony of motion. When run by steam, with all its characteristic sights, sounds, and smells, they take on added interest, almost seeming to come alive.
Ever since childhood days of building crude wood and tin-can toys, I had dreamed of building a genuine operational miniature, and since steam seemed the only practical self-contained power source that could be satisfactorily scaled down, there was no question about how it would be powered. But due to the usual interventions, those dreams were a long time materializing.
By 1972 I had accumulated most of the equipment needed for such a project, realized I wasn't getting any younger, and that I had better get started while such things could still be done. As it turned out, that was a more timely decision than I knew.
What I still lacked was know-how. I had built stationary engines, but this was obviously going to be far more complex. Port-reversing slide valves would be required as a convenience on the main engine and a necessity on the swing engine, and I hadn't the foggiest idea how to make them. Then there would be all the gear ratios, power calculations, clearances, controls, etc. All kinds of information and parts are available for railroad models, but none for this sort of thing.
Faced with all that, plus the skepticism of some who learned what I had in mind (along with no small amount of my own), away I went. At this point I would like to gratefully acknowledge the help I received from fellow Live-Steamers , without which the project may never have been completed, certainly not as successfully as it was. One fellow had a full-size Erie shovel; another was a collector who graciously loaned old parts books and drawings. That solved the valve problem, plus many others.
The first decision concerned size: How big should this thing be? I guessed that a 2-inch-per-foot scale (1/6 full-size) version of a 50-ton crane might be about right. From pictures I built a wood and cardboard mockup. I had guessed right - much bigger would be a transportation problem, and much smaller wouldn't have the weight to dig very well in full-size earth. So with that, I set to work, learning as I went.
What developed was a sort of composite of Bucyrus and Northwest, the makes I had most access to. Except for chains, most plumbing fittings, and spur gearing, it is all scratch-built. The caterpillar track base is 25 inches square, rope size is 1/8-inch 7x19 galv. steel, and the working weight with heavy clamshell is nearly 600 pounds. Its stability was demonstrated when the clam picked up a 50-pound log, nearly a 100-pound total load, with the boom at about 45-deg. and no sign of tipping.
Castings are mostly of zinc alloy and bronze, poured in my shop foundry. All functions are steam operated. Boiler feed water is from three sources: injector, duplex steam pump, and a power pump run by the main engine. There are two double-cylinder engines, one powering all hoist and travel functions, and another (the swing or slewing engine) for rotating the superstructure. I suspect the reason for a separate engine for this function, rather than a clutch system from the main engine as in more modern machines, was that it was simpler since the same engine was used for the crowding action on dipper shovels. In any case, it was an additional challenge, and adds more interest to the operation.
One of the biggest thrills of the entire endeavor was the first test run of the main engine. Going from drawings of the cored steam passages in the full-size to drilled ones on the model, I wasn't sure I hadn't gotten disoriented somewhere until I finally put air to it. With only one side assembled, less stuffing box packing, and with the valve cam set by eyeball, I hesitantly opened the air valve. Much to my relief it ran beautifully in either direction.
The tracks are independently driven through jaw cutches for steering. The two hoist drum clutches are external band worked by steam rams. The brake bands are direct mechanical with over-center toggles. Both are operated by a complex system of links, bell-cranks, and springs from the control station levers, a departure from full-size practice due to the operator being some six times too large to fit inside to use foot pedals. (The pedals ARE functional, though; they lock the levers in clutch position for powering down loads, useful in crane work.) The boom hoist is a separate drum, worm-driven (and self-locking,) from the main hoist gear. The boom is of riveted aluminum angle, 100-inch basic length with 20-inch optional section. Not really a "shovel" (I haven't gotten around to building that attachment yet), it is a crane with heavy and light clamshells and a dragline bucket. Capacity is about 2 scale cubic yards (just under 2 gallons.) To check the geometry and operation, cardboard mockups were tested in sawdust.
After finishing the clamshell I had to see what 45 pounds of bucket would do in real soil, so hauled it out into the garden and hastily reeved it with some old sash cord. What it did (you guessed it!) was break the cord, but not before a quite respectable bite had been taken. On to steam!
The boiler is a conventional vertical fire-tube type, originally steel but now, due to corrosion and maintenance problems, copper. It's big enough to make all the steam needed and is a good counterweight. I first tried firing with wood, but soon found it was a near-full-time job. My first oil-firing attempt was with used engine oil. It was free and burned hot, but only after raising steam with a wood fire like the big ones did in the old days. That problem was eliminated by changing to diesel fuel. I use a small spray-gun type atomizer, and when I get the feed pump at the right rate the boiler pretty much takes care of itself.
In 1978 at the Fall Meet of the Los Angeles Live Steamers, after six years and some 1700 hours of effort, most of it enjoyable, some of it challenging, and all of it interesting, the rig was fully operational. I bravely decided to test myself and the machinery by attempting to pick up an aluminum can with the clam. Considering the vagaries of the control system, distractions from the usual crowd of observers, and my inexperience as a runner, I was sure the can would be crunched into a shapeless bob. To my surprise and relief it wasn't; it hardly suffered a dent. I've never worked up enough nerve to try it again, being content not to drop a load in the middle of a swing!
Allowing for the physics of reduced size, it operates much like the full size rigs, and it's big enough to get into the same kind of trouble if the runner goofs. Fortunately, the troubles are easier to correct. The size choice has proved to be ideal, and the nonstandard control system, though inconvenient when raising suspended loads, has worked very well. (Never having run a full-size machine, I had nothing to unlearn.) Running the clam was no big deal, but the first time I tried the drag line I acquired an instant respect for the runners of the big ones.
Why did I build it? Why does one swim the Channel, or build a Brooklyn Bridge from toothpicks? In this case, as I say, it was a lifetime ambition. I've always liked to watch the wheels go 'round, especially when they're steam powered. And maybe because this machinery is a kind of reminder of a time long-gone when some of our present problems hadn't even been thought of. In any event, I'm glad I did it when I did; one thing I've learned is that if you want to do something, do it as soon as you can, because you never know when it will be too late.
Watching the clam pull itself into the ground as the closing line snakes through all those sheaves, to the sound of the engine and the smell of steam and hot oil, made it all worthwhile. Not to mention the amazement of spectators, most of whom never saw the big ones at work. And the small boy, growing up in the plastic, throwaway age, asking, sort of awestruck, "Is that made out of metal? Steam machinery buffs will understand.
Steam Locomotive (self-propelled) Crane, Caterpillar Mounted
1 1/4 x 11/2 inch double, port-reversing slide valve type. Max. rpm 500.
Indicated hp .7 @ 80 psi Est. torque 51 inch/pounds.
3/4 x 1 double, port-reversing type.
Hoist gear ratio 7.38
Scale pull on main line 116 lbs. (25000/216)
Main drum 3" dia. x 3 1/2"long, capacity 17 1/4 feet/layer of 1/8" rope.
Aux. drum 3 1/2 x 2 1/4, 12'/layer.
For clamshell work both drums 3 1/2" dia. x 2 13/16, 16 1/2'/layer.
Drumshaft rpm 40
Swing rpm 4, total gear ratio 86.4
Boom hoist ratio (from crankshaft) 15.3
Drum 1 1/4 x 1 1/2" long
Line speed, average, 8 1/3 fpm.
Track base 25 x 25 inches, loading (at 600 lbs. total weight) 2.4 psi
Max. travel speed 10 fpm
Gear ratio bull wheel to crankshaft 87.
Travel/rev. of bull wheel 21 1/4"
Weight with 100" boom, 3 gallons water, 1 gal. fuel oil, steel boiler
634 lbs. (less bucket.) (determined by teeter-board/spring-balance method.)
1/6 scale cubic yard=216 cu. in. or .94 gallon.
The following gallery of images is from the construction phase of the steam shovel where you can see some of the techniques used. No captions on any of the pictures yet.