Loading Considerations
© 2000 Dr. B. C. Paul revisions 2009
Note These slides include screen shots from the Caterpillar Performance Manual
Edition 29.
Field Loading
Configurations
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Depends on the type of
equipment used
On the space available
Shovels and Hydraulic
Excavators tend to load in one
set of ways
Backhoes have some variations
FEL have some unique ones
Single Truck Loading
Loader near the face
Truck backs up next to the
loader on the drivers side
(Gives the loader operator a
better view
Loader working into cut in the
face
Loader swings about 120
degrees to dump
Advantages of Single
Truck Loading
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Simple
Truck doesn’t have to back tires
into the rockiest areas
The shovel faces armor of the
tracks into the dig face
Shovel operator has optimized
view of truck bed target
Disadvantages of Single
Truck Loading
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Backing into place can take
around 1 minute and may
require a spotter
• Loaders expensive and idle
• Back time is an unproductive bottleneck
• Can form large ques because trucks
tend to bunch
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120 degree swing angle can be
slow
• Manufactures often rate on 90 degree
More Disadvantages
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Limited Space Available for
Oversize Material
• Can set to side
• Do a bowling ball drop into truck
• Hydraulic shovels can set - but cable
shovels drop bucket bottom open
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Extension cord problems with
electric equipment
• Cord has to cut across truck path
• Putting on poles can cost time
Double Truck Loading
Same Arrangement as
single truck loading only
the trucks pull up on both
side
Advantages of Double
Truck Loading
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Second Loading Spot Allows a
second truck to spot during
loading operations
• Avoids dead time on the loader
• Doesn’t help the truck cycle time
other than eliminating some
queing
Disadvantages of
Double Truck Loading
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Still have extension cord
problems on electric units
Oversize boulder problem is now
even more severe
Forces Loader operator to load
on the blind side (most big
loaders put the cab to one side
of equipment)
Drive By Truck Loading
Shovel Lines up Along
the face
Trucks pull forward and
stop beside the loader
Shovel Swings 90 to 180
degrees to dump
Advantages to Truck
Drive-By
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Greatly Reduced Spotting Time no backing cycle
Cable doesn’t cross the Trucks
Path
Can Set Oversize Beside and out
of the way
Machine marches on a steady
forward advance
Can do in a narrower space
Disadvantages of Drive By
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Often have problems with dipper
swinging over the top of the
drivers cab
• Loader gets revenge for the truck
running over its extension cord
• If the dipper comes open your
truck driver can get dead
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Trucks get to drive those
expensive tires through spills
More Disadvantages
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Lack of spotting makes it a one
shot that can lead to long
swings
Tracks are broadside to long
face area
Modified Drive-By (Or
Getting Fancy)
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Shovel in Drive-By Position
Truck Drives up to Shovel as if it
was a drive-by
• Loading drops onto a moving
target
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While the Loading goes for the
next bite the truck backs into a
single load like position
• Shortens swing distance
Advantages
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Get most of the positioning
advantages of single truck load
without the idle spot time
Disadvantages
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Dump onto a Moving Target
• With swinging over cab can be a
real adventurous feeling for driver
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Gets the tires into some real
rocky conditions
Backhoe Loading
Methods
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Backhoe works below grade
• Can allow work to be kept off wet
pit floor
• can also provide multi-level
loading
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Backhoes generally need good
size machine relative to bucket.
Doesn’t wear as well - generally
used for special conditions
Can Work Double and
Single Truck Loads
Can also Load on
Multiple Levels
Multilevel Loading
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Double Loading configuration
• has extra room for oversize and
still two trucks
• Because truck has to come in on
right level does require some
additional advance data to send
truck to right spot
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Can also get 3 position loading
• often a bit of overkill
Front End Loader
Configurations
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FELs are less expensive than
the trucks and are mobile
Makes practical to consider
more than one loader providing
loading service
Limited lift heights make truck
match more critical
Tires can tear up bad underfoot
Single Truck Loading
Common Loading
Arrangements
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Tandom Loading
• This time there are two loaders
and the truck backs between
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Drive By Loading
Chain Loading
Staggered Tandom
Loading
My Consideration – What
Kind of Turning Radius is
Needed
Turning Radius for Single Truck
Loading
How Big a Truck can I
Use?
About ½ truck width
Turning Radius
Truck Length
About 15 feet for berm and edge clearance
Checking Out Cat 793
(Our biggest option)
43 ft 4 inches long
26 ft 8 inches width
99 ft 2 inches full circle
Turn clearance
(effect 50 ft turn radius)
Plugging In
About ½ truck width
Turning Radius
13 feet
50 feet
Truck Length
43 feet
About 15 feet for berm and edge clearance
15 feet
121 Feet – I don’t have that
Try 777 (789 was similar to
793 in dimensions)
Turn Radius 43 feet
Width 18 feet Length 32 feet
Checking Out the 777
About ½ truck width
9 feet
Turning Radius
43 feet
32 feet
Truck Length
About 15 feet for berm and edge clearance
15 feet
99 ft < 100 ft
Just Works
(smaller trucks ok)
For Single Truck Load
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Cat 777 is the largest that will
work
• One of our two smaller would
leave us a little more room for
comfort
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We could look into drive by but
we might want to consider our
loader options more