Types of Loaders
©Dr. B. C. Paul 2000
Modified 2009
Note – These slides contain drawings copied from the book
Surface Mining Equipment
Loading Equipment

Four Basic Types of Loaders
• Cable Shovel
• Hydraulic Front Shovel (also called
hydraulic excavator)
• Backhoe
• Front End Loader
Front End Loader
F is the Bucket - note
that it is a solid unit.
Dumping is achieved by
rotation. Can be critical
consideration in loading
height
G is Teeth - FELs known
as whimpy diggers
- load is spread over a
bucket as wide as a
machine
- May have penetrating V
Digging Motion of FEL
I, J, H, and E are the hinges
and hydraulics used for
rotating the bucket
- They provide limited
pry and dig motion
C is a one piece arm moved
by hydraulic cylinder D
- Wide bucket
- Rigid Arm
- Limited Pry Pivot on
bucket
Limited Digger
Crowd Motion on an FEL
Oh Cool
It has a
CounterWeight to
help with
Digging
Force
Crowd Motion is the Tires.
The machine drives
forward
- Powered by Diesel
Engine A
Problem of Tearing up
Underfoot under wet
conditions
Hydraulics on arm
competes with propel
motion for power
The Articulated Machine
Front End Loaders are
articulated which gives
them their Y shape loading
pattern
Mobility of FEL makes
great for cleaning up
spills
The Dilemma of Cab
Position


Which side of the articulation
point does the cab go on?
Put it in Front
• Driver has better view of digging
• He is in a better position to get
squished if the pile collapses
• Very bad backing view - this
machine moves fast
The Other Choice

Put the Cab on the Back
• Still a reasonable Dig view with
less opportunity to get squished
• Still rather marginal on backing
view - some things are just
dangerous
• Vibration from motor causes
operator fatigue
• Now putting cabs on flotation
suspensions
Hydraulic Front Shovel
Has a two piece bottom dump
bucket
- Higher wear from two
pieces
- Bottom open eliminates
need to pivot to dump helps loading height
- Can get a rock stuck too
Hydraulic bucket opening for
gentle loading
- can position low over
truck and open bucket at
a controlled rate
The Machine That Digs
It
Machine has two piece are
and a pivoting bucket
- Allows range of motion
like human arm - lots of
dig and pry for hard rock
Can Selectively Pick Out
Rock Layers
- Can be valuable for acid
or toxic layers or prep.
of synthetic topsoil
Hydraulics can develop
100,000 psi at the teeth
The Machine That
Swings
This is a track mounted machine
lacks mobility of FEL
- Picks up load and pivots to
dump into truck
Tracks provide for low bearing
pressure. Coupled with minimal
movement is much easier on
ground - especially when wet
View Arrangements
Cab Location Provides Good
View of Digging Operation
Cab Location to one side
can be a view problem for
loading a truck on the wrong
side
Has a Low Built Upper
Structure to allow open top
access to components - with
5000 psi on hoses you need it
Other Machine
Properties


Power Supply Can be Diesel or
Electric (often Diesel)
Power is converted to hydraulic
for most motions including
propel
• Hydraulics allow trade off between
power and speed at steady engine speed

Very Gradable - Can Pull itself
up with boom
The Backhoe
The Cable Shovel
Basic Design has changed litte
from the turn of the 1900s
Spindly version shown here is
stripping shovel. Was never
popular outside Midwest and
none built since 1969
- had more limited overburden
range than dragline
- operates on pit bottom so
more vulnerable to water
- had lower profit margin than
draglines.
The Mining and Quarry
Version
Tall Massive Machine So Can Load Almost
anything with no loading height problem
Has Cables rather than hydraulics to drive
motions
- Can move in tension but gravity needed
for other motions - dipper door is tripped
and swings open under gravity
Is a track and pivot machine like hydraulic
excavator - big inertia and slower moving
Has same operator cab view problem as HE
Has a full field shop on back
Cable Digging Technique
Has the limited swing up digging
problem of the FEL
Dipper (not called a bucket on this
machine) does not pivot
Cable connections avoid major shock
transfers to boom - lets outlive the HE
Crowd produced by either rack and
pinion on boom or cable wheels
- wheels preserve insulating boom
from shock
Powering Cable Shovels



Except for Mike Muligan’s Steam
Shovel all the big ones are electric
Extension Cord Does Limit Mobility
(one reasons for machine shop on
back)
New SCR and Frequency Control
Systems offer good power control even giant circuit boards
• Simplicity makes high reliability
Comparative
Advantages of Each
Loaders We Are Offered to
Consider








The following loaders are also to be
considered
Cat 994F with a 24.5 yard bucket
Cat 988BLog with a 38.66 yard bucket
Cat 5230B with a 22.5 yard bucket
Cat 5230ME with a 21 yard rock bucket
Cat 345B L series 2 with a 3.3 yard bucket
P+H 2300XPA with a 27 yard dipper
P+H 4100 with a 56 yard dipper
What Must a Good Loader
Do?




It has to be able to handle the
material without tipping over
It has to be able to get the load over
the edge of the truck and preferably
center and heap the truck
It has to be able to fill the truck in a
reasonable integer number of passes
It has to be able to maneuver on the
ground conditions and space
available in the loading configuration
My Decisions

I propose to disqualify all front end
loaders
• Trucks at the bottom of the 3rd bench
will get stuck so the FELs will almost
surely get stuck also
• FEL also has no chance of lifting high enough
to load a truck on the top of a 30 foot bench.

Actually anything that loads from the
bottom of the bench will be down in
the mud
• I’m going to suggest a Back Hoe