3682 Millcreek Road, Salt Lake City, Utah 84109
Cylinder-head of the Western engine the intake manifold and its complex fuel metering linkages are shown. The automatic oiler sits atop the cylinder driven by a slender pushrod. The crudely-marked disk above the drum rotated past a fixed pointer to indicate rotations of the winch drum and thus the position of the cage in the mine shaft.
In the hot, dry Arizona desert about 60 miles northwest of Phoenix lies an idle precious-metals mine, the Vulture. Discovered in the 1860s by Henry Wickenberg and named for the nearby Vulture Mountains, the mine produced in excess of $200 million in gold and silver in its lifetime. The Vulture was shut down in 1942 by a government order that closed all precious-metals mines to concentrate mining efforts on strategic war-materials production. Except for a brief period when the tailings were being leached to recover trace gold, it has lain idle ever since, waiting for better times and for men to return to dig for its treasures.
But treasures besides gold and silver lay hidden in the Arizona desert at the Vulture :Mine. The guarded property still retains many of its antique engines, air compressors, and other mining machinery. Though none are operating, several are unique. The equipment ranges from a little 4' bore hit and miss to an enormous six-cylinder diesel engine built at the turn of the century. Their condition varies from near run able to frozen with rust and stripped of parts. Some are protected from the elements inside buildings while others rust away slowly, fortunately very slowly, in the dry Arizona air.
The mine property covers about 700 acres and is open to tourists who, for a small admission charge, may take a self-guided walking tour around the grounds and 1 through the old buildings. The mine itself goes down 3,000 feet on a 30 degree slope, but is closed I to tourists. The main chamber near the surface at the mine entrance has collapsed leaving 30 to 35 miles of deeper tunnels closed and dangerous.
Mine-Head Winch Engine
Western winch engine for the main shaft of the mine. It drove its cable drum through a huge bull gear and an oak-block clutch within the drum. The two man-sized levers controlled the clutch and brake on the drum. If you were in the mine cage you trusted your life to the man behind these levers.
Cylinder of the Western winch engine. Exhaust is the larger vertical pipe to the left; intake is the smaller pipe with a tee to the preheater around the exhaust pipe.' Note the relatively modern automatic oiler on top of the cylinderprobably needed because the operator was too busy moving the cage up and down the shaft to worry about oiling around.
High on the hill overlooking the property stand the remains of the mine's head frame and the single-cylinder winch engine that hauled men, materials, and ore up and down the main shaft. It is a 25 HP Western with a 10' bore and estimated 20' stroke driving double 4' x 67' flywheels. The engine frame is 65' x 24' and the top of the single horizontal cylinder stands 27' above the engine's concrete base. A 27-tooth pinion drives the 148-tooth bull gear on the winch drum shaft. Cable wound on the winch drum played out over the head-frame bullwheel and down to the cage in the main shaft. Man-sized levers operated the brake and clutch of the winch drum. Miners in the cage trusted their lives to the man operating these levers. Releasing the brake without engaging the clutch would allow the cage to plunge down the mine shaft.
Cable-drum end of the Western winch engine. Note the brake strap around the outer surface of the drum and the clutch ring bearing on the inner surface of the drum. The large disk above the bull gear rotated to indicate the level of the cage in the mine shaft. The small pulley on the side of the flywheel drove the little cooling-water pump in the foreground through a flat belt.
A gear-driven dial indicated the number of turns the winch drum had played out cable and hence the depth of the mine cage in the main shaft. The unique mechanism features a stationary indicator while a crudely-marked circular disk turned behind it.
A small belt-driven water pump provided cooling water for this king of the hill. Being out in the open where a breeze could blow likely made this the only engine on the property that was bearable to operate in Arizona's blazing summer sun.
Nearby in the blacksmith shed stands a huge tank that stored compressed air to drive the rock drills used underground in the mine. Blasting powder in the drilled holes shattered the rock to advance the face of the diggings. In the same shed stands an Ingersoll Rand drill-bit repointer. The business ends of dull drill bits were heated red in the forge, pounded into the point reforming die on the Ingersoll Rand, and then quenched to harden the steel.
The Chicago Pneumatic Air Compressor
Cylinder head of the Chicago Pneumatic compressor and engine. The bulge on the bottom of the cylinder head contains the bulb that was heated by the torch at the left, which was fueled by the small pipe at far left. Immediately behind this small pipe is the compressed air tank that supplied starting air. The 1' pipe on the left supplied starting air, while the larger one on the right carried cooling water. The injector is in the very center of the cylinder head, but the fuel pipe is missing. The large pipe in the right background carried compressed air to the storage tank outside. The huge pipe to the floor carried the diesel exhaust outside and up a 25' stack.
Chicago Pneumatic in-line air compressor and diesel engine. This machine supplied high-pressure air for the rock drills in the mine. The engine section is at the right and the double-acting compressor section is in the middle. The smaller diameter casting at left contains the crosshead. Note the injector push rod along the side, screened diesel air intake at the bottom, and screened compressor air intake at the top. The diesel exhaust went down through the 6' pipe at the base of the cylinder, while the compressed air flowed out the large pipe to the ceiling behind the compressor air intake. Note also the lack of any cam-driven intake or exhaust valves. The governor linkage to the injector return mechanism, the governor drive pulley, and the safety pulley can be seen above the diesel air intake, but the governor drive belt to the crankshaft is missing. The pipe from the floor to the manual valve on the side of the cylinder head carried compressed air for starting. The preheater torch can be seen at the bottom of the cylinder head. Pipes above the machine supplied cooling water for the engine and compressor sections.
The adjacent compressor building is overwhelmed by a Chicago Pneumatic inline engine and air-compressor combination. The engine is a single-cylinder, horizontal, two-cycle diesel with about a 13' bore and 13' stroke. The engine exhausts out a 6' unmuffled pipe that goes down to the dirt floor, outside the building, and up a 25-foot stack beside the sheet-metal building.
The double-acting air-compressor section between the diesel cylinder and the crosshead adds about 40' to the length of the machine. The in-line arrangement and the crosshead make this a very long and lanky machine. It is about 15' 6' long from the tip of the injector pipe in the head to the far side of its 5' x 60' double flywheels. The machine has a 12' x 34' frame casting that stands 33' high. The frame is bolted to a concrete base sitting on bedrock below the dirt floor of the building. A single rod along the side pushed the injector pump once per revolution. The injector return stroke is limited by a flyball governor mechanism driven by a flat belt from the main shaft. The reciprocating mass of the twin pistons, crosshead, and long connecting rod is balanced by massive counterweights bolted to the crank. A crude blowtorch heated a bulb on the bottom of the head enough to fire the fuel when this 40 HP engine was being started.
Left side of the Chicago Pneumatic. The manufacturer's symbol is prominently cast into the crosshead cover plate. The machine is built up from castings bolted together and to a common base casting. From left to right are the cylinder head, diesel cylinder, spacer, air compressor cylinder, and crosshead-main bearing castings. The small centrifugal pump in the foreground circulated cooling water to both the diesel head and cylinder as well as the double-acting air compressor cylinder. The pump's drive pulley is missing from the flywheel. The screened compressor air intake pipe and the air exhaust pipe to the ceiling are clearly visible. Note the massive concrete base on which the machine is mounted.
Imagine what it must have been like to tend that beast. When that engine was working it must have shaken the building and the ground it stood on. The bark of the 2-cycle diesel probably could be heard for miles. The winters are not particularly cold in this part of Arizona, so the heat from the engine and compressor probably kept the building fairly comfortable even if the doors were open. But in the summer when it was 115 or 120 degrees in the shade, the blazing noonday sun must have driven that sheet metal well past 150 degrees! That heat along with the noise from the unmuffled intake of the engine and compressor must have made hell seem cool and quiet by comparison. It would have been like working between a blast furnace and a drop-hammer forge.
Massive flywheels dwarf the lower end and connecting rod of the Chicago Pneumatic. Note the bolt circle on the spokes of the flywheel that mounted the water pump drive pulley.
Clearly this huge machine was not turned over by hand to get it started. An empty concrete engine base, compressed air tank, piping, and hand-operated valve at the head of the engine give convincing evidence the machine was started on compressed air. The operator watched a mark on the flywheel and gave it a shot of compressed air on each revolution to bring it up to starting speed.
The belt running the governor was held taut by a weighted pulley on a swing arm. The injector return stroke was also coupled to this arm so if the governor belt broke, fuel would be cut off to keep the engine from running away at full speed.
Engine end of the Chicago Pneumatic. To start the engine, compressed air was valved into the side of the cylinder head manually with the lever-operated valve in synchronism with a mark on the flywheel. Immediately below this valve is the fuel pipe and blowtorch arrangement used to heat the starting bulb at the bottom of the head. The governor on top, missing one of its flyballs, was spun through bevel gears by a flat belt from the crankshaft. The smaller pulley below swung up to hang on the governor drive belt as a safety measure. It hangs in the fuel cut-off position in the photo. The injector is seen beside the base of the cylinder head where the fuel pipe comes up from the floor. The linkage from the governor varied the return stroke of the injector piston to limit the amount of fuel injected on each stroke and thus controlled the speed of the machine. The hand lever at the injector adjusted the mechanism for the desired amount of fuel.
Various buildings scattered around the property served as bunk houses, kitchen and mess hall, offices, and for other purposes. They stand today in a wide range of decay from fallen down, to falling down, to open-to-the-public. The two-story assay building is open and in rather good shape. Sitting in the corner just inside the door, but missing its head, is a 1 HP Cushman Cub hit & miss. Mine overburden rocks in the walls of the building are said to contain over a million dollars in gold at today's prices.
Off to the south and below the head frame and compressor building stands a two-story sheet-metal and concrete ore-crusher building. One side is a concrete tipple for accumulating ore for processing. Inside, ball mills ground ore so the metals could be extracted. Although the milling machinery is gone, the building still contains two large air compressors. Their prime movers have been removed, and only the massive concrete bases remain as testimony to the size of the equipment they supported.
One is an 8' x 8', 300-RPM, single-cylinder, horizontal compressor made by Sullivan of Chicago. It is class WG6, S/N 10443 had 3' x 39' flywheels'. It was driven by a 7' flat belt gripping a 40' diameter pulley. Its frame is about 74' long x 18' wide and the top of the cylinder is 25' above the concrete base. It was rare to find this much information about a machine. Unfortunately, most builder's plates have been removed from the machinery at the mine by souvenir collectors. Those selfish acts make it especially difficult to identify these machines.
The crusher building also houses a second single-cylinder horizontal compressor. I'd estimate the bore and stroke at about 9' x 9'. It has 6' by 48' flywheels and was driven by a 10' flat belt on a 48' pulley. The frame is 77' x 26' and the top of the cylinder is 19' above the concrete base. With the builder's plate missing, the only clue to its pedigree is the raised letters 'Ingersoll Rand' on its base casting.
A few yards downhill from the crusher building stands the two-story sheet-metal powerhouse and machine shop. The machine shop in the east end contains a rusting Prentice Bros. 16' x 6' engine lathe. A bench grinder and two drill presses complete the shop equipment. No overhead lineshaft hereeach was driven by its own electric motor.
Three-phase AC power was generated in this building to supply the needs of the entire mine complex. Three of the four engines used in the building still remain. Most tragic, perhaps, is a 12 5/8' bore x 15' stroke horizontal, single-cylinder, fourcycle, valve-in-head diesel engine. It sits on an 86' x 36' x 25' high concrete base with the top of the cylinder 25' above the base.
Standing chest high with its 62' double flywheels and 11' x 60' generator drive pulley, it is a short brute of a machine. But why tragic? It seems that after lying idle since 1942, it was fired up in the mid '50s. For whatever reasons, the connecting rod cap broke while it was running and the crank driven by the massive flywheels caught the .loose Tad. The tremendous energy stored in the flywheels bent the rod as it broke pieces out of the piston skirt, cylinder liner, and main casting. And there it sits, 40 years later, broken pieces and all. Repairs must have been contemplated, for sitting on the floor nearby are a spare cylinder liner and piston. Two spare heads in poor shape lay nearby, and a complete engine frame and cylinder rust away outside.
Graydon Gaudy of Cottonwood, Arizona, who was gracious enough to accompany the author on a field trip to the Vulture Mine, indicated this engine could, indeed, be repaired. From the restoration work this man has done, there is little doubt he is right.
This little 3 HP hit & miss engine served the vital role of compressing the air used to start all the other engines in the powerhouse. Although grimy and covered with the caked dust of years of neglect, it still turns over easily. Expert readers can probably identify the manufacturer easily.
This large engine drove a small generator-alternator combination via 1?' vee belts. The generator-alternator has a four-groove driving pulley for the vee belts, but they just ran on the flat surface of the 60' pulley on the engine. The generator portion of the machine supplied the DC current to energize the rotating field coils of the alternator. Three-phase AC power was generated in the stationary windings of the alternator.
The engine is particularly interesting for all the push rods, rocker arms, valves, and plumbing outside the engine. It's interesting to ponder what all the rods, valves, and pipes were for and how they functioned. For example, it has four cam-driven pushrodsintake, exhaust, injector, and compressed airfor starting the beast. Fuel was injected at the top and bottom of the head. A curious bulb-shaped casting above the cam chamber encloses a flyball governor.
Sitting on the floor nearby is the smallest engine in the building. It's a little 3 HP, 475 RPM, horizontal hit & miss. The engine carries number 307840, but no other identification remains. It has a 4 3/16M bore and an 8' stroke, and still turns over easily. Even though small, it had a most important role to play. It drove a two-cylinder air compressor which slowly filled a 6' tank outside the building with enough air to start the single-cylinder diesel and its bigger brothers.
The Union Engine
Alternator end and camshaft side of the Union 6-cylinder diesel. The smaller, belt-driven machine is the DC generator which supplied power through two slip rings to energize the magnets of the alternator rotor. Three-phase 60-cycle power was taken from the outer, stationary windings of the alternator. The walkway is 6 feet above the floor.
Rocker-arm detail of the Union 6-cylinder diesel. With cover raised, the three rocker arms and valves of #3 cylinder are visible. Rollers reduce the friction between the rocker arms and the camshaft. The longer, outer rocker arms are for intake and exhaust while the shorter, center rocker drives the injector pump.
Dominating the room is a gigantic 6 cylinder, four-cycle diesel engine. Opinion varies as to where it was madein Germany or in the U.S. under German patentsbut the word 'UNION' is cast into each of its 12 crankcase cover plates. The engine stands over 10 feet tall and is over 15 feet long. The assembled upper and lower crankcase castings are 14' 8' long, 47' wide, and 38' high. They are split at the horizontal centerline of the crankshaft.
Each cylinder and water-jacket casting is 22' in diameter x 40' tall. They are individually bolted to the crankcase through 22' square, 8' thick flanges. I'd estimate the bore at about 18' and the stroke perhaps 20'. It is an overhead-cam design with three lobes per cylinderintake, exhaust, and injector. The cam is driven by a vertical shaft at the rear of the engine via two sets of offset right-angle gearing.
An overhead walkway, 6 feet above the floor, surrounds the cylinder heads so the engineman could make adjustments and see to their proper operation and lubrication. The engine carries a 7' x 69' flywheel and a smaller, precisely marked timing drum. The flywheel is notched and a prybar is rigged so the engine can be turned over slowly to time and set the valves from the marks on the drum. Yes, I did try. The engine still turns fairly easily for its size.
Last run in 1954, the Union engine was shipped to the mine fifty years earlier in 1904- It came disassembled, but with a German engineer to install, assemble, and get it running. It was brought by ship around the horn, up the Gulf of California and then by barge or steamer up the Colorado River to Ehrenberg. There, the many crates were loaded on freight wagons for the 115-mile dirt road trip to the Vulture Mine. Handling those two massive crankcase castings and the crankshaft itself must have been interesting.
This huge engine drove a three-phase alternator 80' in diameter and 8' thick with a 56' diameter, 26-pole field structure. With 26 poles, it had to run at 277 RPM to produce 60-cycle power. A set of three vee belts drives its exciter generator which produced 50 amps of 250-volt DC power to energize the 26 field coils of the alternator through two exposed slip rings.
The electrical panel beside the alternator contains meters which give a clue to the power this engine delivered. The AC voltmeter on the panel ranges from 1000 to 3500 volts indicating the system probably produced 3000 or 3200 volt line-to-line AC power. The AC ammeter's range of 80 amperes (probably line current) and the range of the voltmeter seem to indicate the panel could measure upwards of 440 kilowatts. Assuming a 70% alternator efficiency, the diesel would have to deliver 628 horsepower to generate that much power. The 320-kilowatt range of the wattmeter is not inconsistent with this speculation because it could have been switched to two different line-to-line connections each measuring about half the system's total generated power.
Other meters on the panel include a synchroscope and a pyrometer. The synchroscope indicated the generated AC power was above or below the desired 60 cycles per second. The pyrometer measured the exhaust temperature of the diesel engine and could be switched to make that measurement at any cylinder. The only concessions to safety are a thick rubber mat below the electrical panel and handrails around the rotating machinery. Rheostats and switchgear at the panel complete the control equipment. Off to the side, under inch-thick dust, lay many small electrical service parts.
The fourth engine is missing from the powerhouse, but its concrete base gives evidence of its size, configuration, and purpose. It was likely a mid-sized, in-line, vertical diesel driving an alternatorperhaps for auxiliary power.
Head end of the Fairbanks Morse 15 HP model Z hit and miss engine. Except for a missing exhaust rocker arm and broken exhaust-rocker support, this engine is in fairly good condition.
At least two other hit & miss engines exist on the property. One 8' x 9' with 2' x 41' flywheels lays in the native desert brush northeast of the assay building. Valve gear, carburetor, and magneto are missing. This 10 HP shotgun style engine, probably Fairbanks Morse, carries s/n 323598. On the south side of the parking lot is a 15 HP Fairbanks Morse Model Z in fairly good condition, but missing the exhaust rocker arm and with a broken exhaust-rocker support.
East of the parking lot are two more air compressors. All that remains of one are the two cylinders of a vertical compound. The other is a Chicago Pneumatic two-cylinder, horizontal compound with a single central driving pulley and flywheel. Those who've fought the battle of freeing frozen pistons and bearings, scraping rust, and rebuilding parts would face an extra challenge in restoring this one. Its air-intake manifold is full of angry wild bees intent on protecting their combs of honey.
John Osborne, the caretaker at the Vulture Mine, can be reached at P.O. Box 1869, Wickenberg, Arizona 85358. Write to get the days and hours the mine is open to visitors. The best seasons to visit are the cooler late fall, winter, and early spring months. Avoid the searing heat of June through August. Directions: From Phoenix, head northwest on U.S. 93 &. U.S. 60. In the middle of Wickenberg, take U.S. 60 west, under the railroad tracks, and go 3.3 miles to Vulture Mine Road. A shopping center is on the south side of U.S. 60 just west of this road. Turn south and go 11.5 miles on a winding paved road to the mine entrance. Turn right, follow the signs, and park in the lot. Pay admission at the curio shop and enjoy the self-guided tour, but please don't collect souvenirs. The artifacts left behind could be the key pieces in restoring an engine.
For those interested in more history of the mine, visit the Arizona Mining Museum at 1502 W. Washington in downtown Phoenix. A free parking lot is next to the building. Ask to see the Vulture Mine file. It contains lots of history and stories about the mine, but very little about the machinery still there.
The Vulture Mine represents a unique challenge to gas-engine hobbyists. Most of the equipment could be restored if taken to shops off the property. The challenge is to restore and run them at the mine to make an operating museum featuring the prime movers used in the early 20th century.