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16-46 Edition 47
Electric
Rope Shovels
MODEL
7295
7395
7495 HD
7495
Dipper Range
19.1-
38.2 m³
25-
50 yd³
20.6-
55.8 m³
27-
73 yd³
27.5-
60.4 m³
36-
79 yd³
30.6-
62.7 m³
40-
82 yd³
MODEL
7495 HydraCrowd
7495 HF
7495 HF HydraCrowd
Dipper Range
30.6-62.7 m³
40-82 yd³
30.6-62.7 m³
40-82 yd³
30.6-62.7 m³
40-82 yd³
Information subject to change.
Dipper Selection
DIPPER SELECTION
Selecting the correct dipper size plays an integral role
in maximizing productivity from a truck shovel opera-
tion. Optimal dipper size is a function of truck size,
material loose density, and fill factor.
The first step in calculating dipper size is to deter-
mine the machine’s optimal payload based on truck
size. To calculate this, divide truck payload by three and
four (three or four pass even loading is ideal for high
productivity). Compare these values to the machine’s
maximum payload. The machine’s optimal payload is
the largest value that is less than the maximum payload.
For example, consider a mine operating a 7495 shovel
(maximum payload = 120 tons) and 797 trucks (pay-
load = 400 tons). 400 ÷ 3 = 133.3 and 400 ÷ 4 = 100.
133.3 can be eliminated as it is greater than the shovel’s
maximum payload (120 tons). 100 tons is the largest
value less than the machine’s maximum payload, and
therefore, is the machine’s optimal payload.
Once optimal machine payload is determined, mate-
rial loose density and fill factor are used to calculate
the optimum dipper size. To calculate material loose
density, divide insitu (undisturbed material density) by
1 + swell factor.
Material loose density =
Insitu
(1 + swell factor)
Once material loose density is calculated, use the equa-
tion below to find the optimal dipper size. Fill factor is
affected by the dipper geometry, rake angle, and mate-
rial properties, including fragmentation and critical
angle of repose. Fill factors are generally between 90%
and 115% for efficiently-sized dippers.
Optimal dipper size =
Optimal machine
payload
Material loose
density
× Fill factor
For example:
For a mine with the following conditions:
Insitu: 2.276 ton/yd³
Swell factor: 35%
Fill factor: 95%
Optimal machine payload: 100 tons
Optimal dipper size =
100 tons
2.276 ÷
(1 + 0.35)
× .95 = 62.5 yd³