SHERMAN
HILL SUMMIT
AND
UNION
PACIFIC BIG BOY LOCOMOTIVE
Research
of topics under discussion at the 8 am coffee hour at
Wescoats
Corner & Five Points Arbys.
The
1885 era of the Union Pacific railroad's saw locomotives
struggle
to move trains of 3600 tons over the Wasatch mountains
between Ogden, Utah and Green River. Wyoming.
These
mountains held the 176 miles of track beginning at
Ogden,Utah, sitting at 4300 feet above sea level, climbing the
Wasatch
Range, to 7300 feet at Aspen tunnel, then down to Green River,
Wyoming, sitting at 6100 feet above sea level.
On
occasion Union Pacific had to combine three or more steam
engines
to assist heavily loaded trains over the Wasatch mountains.
Early
1940's when the Union Pacific was enjoying a period of
high
earnings and profits, the company under a new president , William
Jefferies,
ordered built, an locomotive that could pull 3600 tons over
the
Wasatch Range unassisted..
Also
on the mines of American manufacturers and transportation
managers
was the eventual entering of the United States in World War II
which was already putting additional traffic on the heavily
traveled
Ogden - Green River route.
In
Omaha, Nebraska's Union Pacific's Department of Research &
Mechanical
Standards, Otto Jabelmann, calculated that 135, 000 lb.,
of
'tractive effort' was needed for the engine ordered built for
Jefferies to
achieve
it's goal. The engine was quickly designed and the American
Locomotive
Company agreed to build such a locomotive. These new
engines
were given trade numbers of “4000 Class” and were to be named
Wasatch
series, however, a worker wrote “Big Boy” on the front of
the
first
engine as it was being built and that name 'stuck'. Union Pacific
already
had the Challenger built in 1936, but Big Boy was larger,
heavier
and required Union Pacific to lay heavier rails and realign
curves.
With
the tender Big Boy was the largest steam locomotive built that
could
operate
on existing standard gauge railroads.
But
wait, an interruption, “tractive effort', what is that?
Calls for another research period. So it be.
PAGE
TWO
Tractive
Effort, or Tractive Force, a mechanical engineering term,
refers
to the total traction a vehicle exerts on a surface or the
amount
of
total traction parallel to the direction of motion. Got that down
and
understood
? I bet.
Railroad
engineering holds the term 'tracfive effort' is used to
describe
the pulling or pushing capability of a locomotive.
The
term tractive effort is starting tractive effort, continuous
tractive effort, and maximum tractive effort, and are related to
common
mechanical
factors , input torque to the driving wheels , the wheel
diameter,
coefficient of friction between the driving wheels and the
supporting
surface, the weight added, is the factor of adhesion that
determines
the maximum torque that can be applied before the onset of
wheelspin or wheelslip. Starting tractive effort, is the
tractive force
generated
at standstill, determines the train weight a locomotive can
set
in motion, maximum tractive effort is the highest force under
a
condition
not injurious. Continuous tractive effort is the tractive
force
to
be maintained , before the system overheats. “Power at rail”
is a
railroad
term for the available power for traction or the power available
to
propel the train.
We
intend to have Warren explain this “tractive effort” thing to
us
in
more detail so perhaps the following will be some help .
An
estimate tractive effort of a steam locomotive can be obtained
from
the cylinder pressure, cylinder bore, the stroke and diameter of
the
wheel
. Torque depends on the driving rod angle made with the
tangent
of
the radius on the driving wheel. The driving force is torque
divided
by
wheel radius, thus: d = d2 sp / w X 0.85.
OK
Lets get back to Big Boy, a 4- 8-8-4 locomotive, the only one
to
be so, the front leading truck, had 36 inch wheels, following
were 8
wheels,
68 inches, the drive wheels, driven by a piston to each 4
wheel,
followed
by 8 more drive wheels identical to the first. Under the cab was
a
4 wheel trailing truck with 42 inch wheels. Each set of 8 drive
wheels
had
its own frame and was articulated which allowed Big Boy to handle
20
degree curves. Number 4000, the first Big Boy locomotive delivered
, was on track by 5 September 1941.
PAGE
3
All
Big Boys were 132 feet, 10 inches long, the engine being 85
feet,
9-1/2 inches long, the tender was 47 feet, 5 inches long. The
height
of
the locomotive was 16 foot, 2-1/2inches. Locomotive and tender
were
a
maximum of 11 feet. 6 inches wide. The weight, engine was 772,250
pounds,
436,500 tender for total of 1,208, 750 lbs . Almost 605 tons.
The
tender, named 'centipede' because of it's 14 wheels, each one 42
inch
tall. The tender could carry 64,000 lb of coal. It also carried
25,000
gallons
of water in a rear compartment. Big Boy was designed for a
top
speed of 80 mph. Seldom did it ever exceed 50 mph and over the
mountain
it was down to 12 mph. At a speed of 41 mph there was 6290
hp
at the drawbar. Each drive wheel rotated 202 times a minute. This
called
for
12,869 cu ft of steam every minute.
The
cab had four seats for a three man crew. An Engineer, fireman, and
breakman. In 1944 the class 2 Big Boy cost $319,600.
The
Ogden to Green River 76 mile run would take at least four hours,
uphill,
a clime of 2500 feet. Under full steam the Big Boy consumed
22,000
lb of coal ans 12,000 gallons of water per hour.
As
diesel locomotives became the prime mover, Big Boys soldiered
on
and were the last steam engines used in regular service. There
had
been
17 Big Boys locomotives total in operation for 20 years.
Sherman
Hill Summit is the highest point of the Union Pacific
Railroad's First
Transcontinental Railroad at 7247 feet. It had first
been
named Lone Tree Pass and Evans Pass. The town of Sherman was
a
train stop where engines were changed, had a roundhouse,
turntable,
water
tank, and section houses. There were maybe 100 residents of
Sherman, a general store, post office, school, two hotels and two
saloons.
Abstract:
Wikipedia, and William Pearces' Old Machine Press, www,
by
Harrison H, September 16, 2018, for
www.iinni,blogspot.com and facebook's
Harrison
H page.
Abstract:
(if you want to call it that OK) September 15, 2018,
&
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