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Enter data in yellow colored cells only. Use
tab key to advance to open cells.
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Seconds-Minutes
Calculator
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Enter
seconds here:
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Read decimal minutes here:
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Enter
decimal minutes here:
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Read seconds here:
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Base
Cycle Time of Excavator (Can Be Wheel Loader) & Wait-Repositioning
Allowance
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The
three listed cycle times are only a guide.
Cycle time depends on where the excavator is situated, material
hardness, arm length, etc. In mass
excavation, a base cycle time of 15 sec. is not uncommon with a skilled
operator. Prospect experience is the
best guide. Repositioning normally
averages only a second or two per cycle.
Excavator wait time can affect the job immensely. If the excavator operator cannot
immediately load the next truck in position and has to wait until the loaded
truck pulls out and the next one pulls into position, you might have a half
minute or more of wait time (to be prorated over three or more
cycles--whatever is normal for the size of excavator). This can greatly affect the number of
trucks put on the job.
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Once
you have entered data for the first four cells, the spreadsheet calculates
(on the right) the number of unrounded excavator cycles per truck load. If this figure is not a whole number, it
will be rounded up to the nearest whole number for the load time calculation.
Example: 3.5 will be rounded to 4 because the excavator must make 4 passes
for 3.5 bucket fulls. It is often more
efficient to make only fully loaded passes, especially if the excavator
becomes a bottleneck in the operation (see below). If your prospect makes only fully loaded
passes and does not want the excavator cycles automatically rounded up--say,
from 3.2 to 4, enter on X in cell B17.
Using one fewer cycle per truck load will shorten all cycle times and
should allow more trucks to be used on the job.
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Haul
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The
haul can have several sections. If the
grade or haul road condition changes more than nominally, you will need to
add a new section. Enter the section
distance in feet/meters, the percent of an adverse grade, or a favorable
grade, and the haul road factor from the list on the sheet. Use whole numbers only. The maximum total resistance (grade + haul
road) is 60. If you have the degree or
the ratio of a grade, use the grade calculator to obtain the percent of the
grade. Note that the haul road factors
must be increased or decreased by a factor of one for each 2,000 lbs. (907
kg) over/under the rated payload (do not round up). The increase or decrease
factor is calculated for you in Cell D47, and is limited to three points of
increased or decreased resistance.
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Fill
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Depending on the size and the amount of maneuvering on the fill
area, select a positioning and dump time--three times are listed as guides.
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Return
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Note
that the return is not necessarily the reverse sections of the haul. The departure spot from the fill may be
different, and even the haul road may not be the same. Make careful note of
any sharp turns on the return. The
program calculates for straight travel.
A sharp turn on a high speed haul road will cause a delay usually of 8
- 12 seconds.
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Delay
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Confer with the prospect about anticipated delays. The
spreadsheet accounts for acceleration and deceleration times between
sections, but does not account for sharp turns or obstacles.. Add about 12 seconds
for each sharp curve or other obstacle on a high
speed section, especially on the haul where it takes longer to accelerate to
max speed. Do not factor in any wait
time in the loading area. The
spreadsheet is based on just-in-time arrival, so any positioning time where
the excavator is waiting for the truck to be spotted must be accounted for in
the excavator load time.
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Total
number of BCY/BCM (or Tons) to be moved and
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Number of hours for job
completion
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Although the spreadsheet will calculate cycle times and
production without inputting the two numbers called for above, most users
will want to know how many trucks to run on the job, and they would also want
to use the separate Job Cost Analysis spreadsheet to calculate cost per yard
of material moved and total cost. Use the Tons per Hour entry section for material handling
applications.
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Production
Estimate
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These
are calculated values. Cycle times are
listed in minutes and then separately in seconds. Average speed is based on the haul, return,
and delay, not on total cycle time.
Compare the number of ADTs needed to complete the job on time with the
maximum number that can be employed.
The latter figure means that you cannot increase production by adding
more trucks--excavator size or cycle time or wait time won't permit it. Also computed is the time required for
various numbers of ADTs to complete the job.
If the prospect wants fewer than what is listed, input the number in
the yellow highlighted cell.
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