The Vulture Mine Engines

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Cylinder-head of the Western engine.
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Head of the single-cylinder diesel. From the top, pushrods actuate the injector, intake, exhaust, and starting-air valves. A spare valve lies across the intake pushrod and spring.
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Head end of the single-cylinder diesel. One drive belt remains in position while another lies limp over the flywheel shaft. The little hit & miss sits on the floor in the background.
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Sullivan single-cylinder air compressor in the ore-crusher building. The crankcase cover was removed to show rod and crank detail.
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Ingersoll-Rand single-cylinder air compressor in the ore-crusher building.
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Little 3 HP hit & miss engine.
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Alternator end and camshaft side of the Union 6-cylinder diesel.
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Head end of the Fairbanks Morse 15 HP model Z hit and miss engine.
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Fairbanks-Morse 10 HP shotgun hit and miss engine rusting away in the desert air with loose head and many missing parts.
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Western winch engine for the main shaft of the mine.
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Rocker-arm detail of the Union 6-cylinder diesel.
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Cable-drum end of the Western winch engine.
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Cylinder of the Western winch engine.
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Cylinder head of the Chicago Pneumatic compressor and engine.
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Chicago Pneumatic in-line air compressor and diesel engine.
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Left side of the Chicago Pneumatic.
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Massive flywheels dwarf the lower end and connecting rod of the Chicago Pneumatic.
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Engine end of the Chicago Pneumatic.

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

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

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

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

 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

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.

 Mine Facilities

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

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

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.

The Powerhouse

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

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

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

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

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

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.

Other Equipment

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

 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.

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Preserving the History of Internal Combustion Engines