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SHOVELS
William S. Otis, of the firm
of Carmichael, Fairbanks
and Otis, when living in
Canton, Massachusetts in
1834 and 1835, while his
firm was performing grading
work for the Boston &
Providence Railroad built
the first steam excavator - a
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., ۸۸ EARLY
. (۱
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SHOVELS
Front shovels are used
predominately for hard
digging above track level
304 توق erin.
shot rock
would be a
typical
application. =
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STEP 1: BUCKET SIZE
Shovels can usually be
equipped with different
size buckets. Bottom
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STEP 1: BUCKET SIZE
Buckets are rated in both
heaped and struck
capacities.
Both PCSA and SAE use a
1:1 angle of repose for
evaluating heaped bucket
capacity. CECE specifies a
2:1 angle of repose.
Heaped Capacity is the
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STEP 2: FILL FACTOR
The Fill Factor adjusts
Heaped Capacity in Icy
based on the type of
anew handlosada
Table 9.1, page 258
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STEP 2: FILL FACTOR
HEAPED BUCKET
CAPACITY
x FILL FACTOR
= VOLUME (Icy)
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STEP 3: CYCLE TIME
There are four elements
in the production cycle
PL aathnralet
2.Swing with load
3.Dump load
4.Return swing
See page 260
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Rr
STEP 3: CYCLE TIME ‘Wp
Height of cut affect. ~~
shovel production.
Optimum height of cut
ranges from 30 to 50% of
maximum digging height,
with the lower percentage
being representative of
easy-to-load materials,
حون ال ينو يديت اس ین wie اسلا سین وی
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STEP 3: CYCLE TIME
Angle of swing affects
shovel production. If the
angle of swing is
increased, the time for a
cycle will be increased,
whereas if the angle of
swing is decreased, the
time for a cycle will be
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STEP 3: CYCLE TIME
Ideal production of a
shovel is based on
operating at a 90° swing
and optimum height of
cut. The effect of the
angle of swing on the
production of a shovel is
6 7 5۲ ._f_gi..g. Feo i rr ft. fr ew
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STEP 4: EFFICIENCY
FACTOR
When selecting a minutes
per hour efficiency factor
visualize the work site and
consider:
٠ Materials being handled,
bank or
broken
¢ Size of the shovels’s
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STEP 5: CLASS of
MATERIAL
Production
will be in
Icy, will
need swell
factor to
adjust to
bey.
TARIF 4.3
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STEP 6: PRODUCTION
Working mins/ hr
Total cyde time (min)
X Heaped Capacity (Icy)
xX Fill Factor
X height/swing
factor
= Production
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