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Loading Considerations
© 2000 Dr. B. C. Paul revisions 2009Note These slides include screen shots from the Caterpillar Performance ManualEdition 29.
Field Loading Configurations
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 abetter view
Loader working into cut in thefaceLoader swings about 120degrees to dump
Advantages of Single Truck Loading
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
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
120 degree swing angle can be slow• Manufactures often rate on 90 degree
More Disadvantages 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
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 onlythe trucks pull up on bothside
Advantages of Double Truck Loading
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
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 Alongthe face
Trucks pull forward andstop beside the loader
Shovel Swings 90 to 180degrees to dump
Advantages to Truck Drive-By
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
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 Trucks get to drive those
expensive tires through spills
More Disadvantages
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)
Shovel in Drive-By Position Truck Drives up to Shovel as if it
was a drive-by• Loading drops onto a moving target
While the Loading goes for the next bite the truck backs into a single load like position• Shortens swing distance
Advantages
Get most of the positioning advantages of single truck load without the idle spot time
Disadvantages
Dump onto a Moving Target• With swinging over cab can be a real
adventurous feeling for driver Gets the tires into some real rocky
conditions
Backhoe Loading Methods
Backhoe works below grade• Can allow work to be kept off wet pit
floor• can also provide multi-level loading
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
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
Can also get 3 position loading• often a bit of overkill
Front End Loader Configurations
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
Tandom Loading• This time there are two loaders and
the truck backs between Drive By Loading
Chain Loading
Staggered Tandom Loading
My Consideration – What Kind of Turning Radius is
Needed
Turning Radius for Single TruckLoading
How Big a Truck can I Use?
About 15 feet for berm and edge clearance
About ½ truck width
Truck Length
Turning Radius
Checking Out Cat 793(Our biggest option)
43 ft 4 inches long
26 ft 8 inches width
99 ft 2 inches full circleTurn clearance(effect 50 ft turn radius)
Plugging In
About 15 feet for berm and edge clearance
About ½ truck width
Truck Length
Turning Radius
15 feet
43 feet
50 feet
13 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 15 feet for berm and edge clearance
About ½ truck width
Truck Length
Turning Radius
9 feet
43 feet
32 feet
15 feet
99 ft < 100 ftJust Works(smaller trucks ok)
For Single Truck Load
Cat 777 is the largest that will work• One of our two smaller would leave us
a little more room for comfort We could look into drive by but we
might want to consider our loader options more