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CAPITAL EQUIPMENT NEWS
AUGUST 2017
12
of job conditions includes the assessment
of desired productivity, material densities,
working hours, type of ground, dump
heights and ramps, among other things.
“It gives you the needed info for a proper
machine sizing, which always starts
with the key metric of a wheel loader:
its payload. A proper payload choice
guarantees the desired productivity and
optimised costs,” says Torres.
McNeil says to know the right sized
machine, one needs to calculate what size
of wheel loader is going to deliver the most
productivity with the least idling time for a
particular operation. But, how best do you get
this right? Brandauer says a number of factors
need to be considered. These include required
capacity per day/shift/month; material filling
factor of the bucket; loading cycle (distance/
time); working hours per day/shift/month; idle
time/breaks per day/shift/month; material
density; and average speed of the wheel
loader. “With these figures you can calculate
the right size of the bucket, which in turn
allows you to choose the right sized wheel
loader,” says Brandauer.
According to Tuntland, one of the most
effective ways of sizing a wheel loader or
any loading tool is through a site assessment.
“Caterpillar and its dealers are equipped
with system application specialists that
can perform this assessment. For existing
sites, it is very important to measure the ‘as
is’ production capabilities. This is done by
capturing various parameters from the site:
cycle times, payloads, fuel burn, production
per hour, haul road profiles, among others,”
he says. “Once this is complete, data can
be compared with production targets.”
Additionally Caterpillar has the capability
to run “to be” scenarios in its own software
tool by changing parameters: loading tools,
hauling units and even haul roads.
Schmitt also believes sizing the machine
plays a big role. He says there is need to
consider the conditions on site. “For sure, the
productivity requirements for bucket size and
cycle time play a major role. However, you
also need to consider matching the equipment
to avoid any losses in the production process,
for example, due to a long loading time or
idling of the hauling units in the supply
chain,” he says. He also believes that the
daily schedule also plays a role. “Often you
see during rush hours a queue of customer
trucks waiting to be loaded – if it takes too
long you may disturb the job site.”
Schmitt adds that the most common
reason for high costs per tonne are oversized
machines versus the required production
output. Oversized machines have a higher
initial purchase price, higher running costs
and usually also higher idling times. “The
Volvo SiteSimulation software helps to
select and define the right machine for the
production targets and or hauling units. Volvo
SiteSimulation makes it possible to provide
different scenarios and makes efficiency gains
immediately visible,” says Schmitt.
Fuel efficiency
Fuel efficiency is always one of the key
considerations when choosing any piece of
equipment for the job at hand. While fuel
efficiency is achieved through a number of
initiatives, the choice of a wheel loader’s
driveline plays a bigger role in the overall
efficiency. “The choice of the driveline is
very important for fuel efficiency. With
Liebherr’s hydrostatic driveline you need
less rpm to get the same output on torque
as on a wheel loader with torque conver ter.
Less rpm means less fuel consumption,”
says Brandauer.
McNeill says hydrostatically driven
machines are generally deemed to provide
better fuel efficiency advantages, but the
customer pays for this with the higher capital
cost, as well as repair and maintenance costs
associated with the machines. “Bell wheel
loaders are direct drive vehicles with an
automatic transmission and torque converter.
They deliver similar fuel efficiency, because
it is not only the drive that impacts this, but
are less complex and less costly to maintain,
while being suited to all applications,” says
Brandauer.
According to Tuntland, overall configuration
is very important when it comes to efficiency.
“Just to name a few: ride control, axle oil
cooler, standard lift or high lift, bucket,
tyres, all have a significant impact on fuel
efficiency. As you can imagine anything that
slows down production will in turn decrease
efficiency. Factors such as ride quality, reach,
dump clearance and stability, can all have an
impact on production. It’s very important that
the machine is configured correctly for the
application,” he says.
WHEEL LOADERS
Bell wheel loaders are direct
drive vehicles with an automatic
transmission and torque converter.
CASE´s wheel loader technology has
five effective electronic systems to
increase machine efficiency.