Before self-propelled haulage vehicles, operators transported
aggregates, ore, waste and fill by traditional means
and repetitive standards. This format included loading
the material into a box supported by a single axle drawn by a
mule or horse and led by a driver using a short harness.
Through repetition, the animals quite often learned to
make the journey to and from the load and dump locations
without a driver, however a driver needed to turn the cart
around for dumping and positioning the cart for loading.
Over the years, the internal combustion engine driving the
rear axle replaced the horse and mule.
While the performance advantages of speed and payload
have grown with the development of larger and larger
engines, transmissions and tires, the basic design of the
haulage vehicle remains the same. A loader puts material
into a box largely supported by a single axle that is driven by
a power plant and guided by a driver. The vehicle backs into
its loading position, travels to the dump area where it turns
around and dumps its load, then travels back to the loading
area where it turns around and starts the next cycle.
The haulage cycle:
Today’s large haulage vehicles have grown into behemoths
with payloads of hundreds of tons,driven by power plants of
thousands of horsepower. But despite their huge size and
capability, they still follow the path of the horse-drawn cart.
Be it overburden and ore at a mine site,aggregate and fill for
road building, or one of the many other applications of the
large capacity haulage truck, the haulage cycle is the same.
There is no escaping the fact that the truck must make two
180-degree turnarounds per cycle. In addition, today’s haul
trucks must also reverse into position for dumping and
depending on the loading procedure, must also stop and
reverse into position for loading.
The patented vector-neutral truck eliminates the turnaround
and back-up sections of the haulage cycle offering a
performance advantage.
The driver sits amidships (between the two axles) facing perpendicular
to the line of travel.He drives by watching a multiple-
screen display that is fed by multiple redundant cameras
that produce a virtual view of the vehicle’s travel path.
The truck drives directly to the load pick-up area without
turning around. The payload is deposited into a dump
bucket that is hinged on the main frame to discharge the
load.The truck then drives toward the unloading site, again
without turning around.Once at the site, the bucket unloads
and the whole process is repeated.
There is no differentiation in driver control and operation
of the vehicle with respect to the direction of travel. It is
insensitive to direction; hence its name, vector neutral.
The major performance advantage of the vector-neutral
truck is in the timesavings gained by not having to turn
around and reverse with every haulage cycle.
There are many more benefits flowing from the
vector-neutral truck’s haul cycle in addition to the straight
time and distance advantages. Fewer brake and steering
applications mean reduced wear on the entire drive train,
including less scrub and wear on tires. There’s less
road maintenance because of the elimination of the
turnaround area and it is simple to adapt remote and
automated vehicle control.
In addition, there is a reduced effect on the environment
and the conservation of energy that results from travelling a
shorter distance.
THE COMPARISON:
The two conventional trucks, a 60-ton
capacity mechanical-drive Terex TR-60,
and the multi hundred-ton capacity,
electric-drive truck, the Liebherr T282,
have the following common design. A
power plant drives a rear axle with
four tires either through a mechanical
transmission or through electric wheel
motors. The front axle, made up of
two independently suspended tires and
wheels largely supports the power
plant. A driver sitting above the axle
facing forward steers the truck. The
payload is deposited into a dump
box that is then hinged to discharge
the load.
60-ton conventional carrier:
The TR-60 (Terex, 1998) has a 650 hp
engine, located above the front axle,
driving a single rear axle through
a mechanical transmission. Four tires
on the drive axle carry half of the
vehicle weight when the vehicle is
empty and two-thirds of the vehicle
weight when it is fully loaded.
The drive axle is connected to
the main frame by a variable rate
nitrogen/oil cylinder, with “A-frame”
linkage and lateral stabilizer bar.
The front axle is comprised of
steerable Kingpin type suspensions,
steerable rubber-tired wheels that
combined carry half of the vehicle
weight when the vehicle is empty and
one-third the vehicle weight when the
vehicle is fully loaded. Overall dimensions
for the TR-60 are: 9.2 m long,
4.4 m wide, 4.4 m high, with a minimum
outside turning radius of about 9.9 m.
The driver sits above one of the
front wheels facing forward. The
payload is loaded into a dump bucket
with a heaped capacity of 35 m3 that
is hinged on the main frame.
400-ton conventional carrier:
The Liebherr T282 has a 2700 hp
engine located over the front axle,
driving a single rear axle through an
electrical drive system. The rear drive
axle is connected to the main frame with
a three-bar linkage that is suspended
on nitrogen/oil cylinders. Four tires on
the drive axle carry slightly more than
half the vehicle weight when the
vehicle is empty and two-thirds of the
vehicle weight when it is fully loaded.
The front axle is comprised of two
steerable, independently suspended
Kingpin-type structures that combined
carry just less than half the vehicle
weight when the vehicle is empty and
one-third of the vehicle weight when
it is fully loaded.
The Liebherr T282 dimensions are:
14.8 m long, 8.8 m wide, 7.5 m high,
with an outside estimated turning
radius of 16.2 m. The driver sits
above one of the front wheels facing
forward. The payload is loaded into
a dump bucket with a heaped capacity
of 183m3 that is hinged on the
main frame.
Vector-Neutral Truck:
The vector-neutral truck has the
same power plant as the conventional
trucks. It is mounted amidships in the
main frame, driving two axles through
a mechanical transmission or electric
wheel motors. Each of the two axles
has four tires, which carry half the
total vehicle weight, both when the
truck is loaded and empty.
The suspension members for the
two axles are the same type of suspension
components found on the rear
suspension of the conventional truck,
a three-bar linkage that is suspended
on nitrogen/oil cylinders. These suspension
members are fixed to a slew
bearing that allows rotation of the
axle and suspension about a vertical
centerline. Rotating the axles equally
and opposite to each other on the
slew bearings steers the truck.
The vector-neutral truck design has
a horizontal pivot added to one of
the two axles to accommodate roadway
irregularities without transferring
torsion loads into the main frame.
Today’s large haulage vehicles have grown into behemoths with payloads of hundreds of tons, driven by power plants with thousands of horsepower. But despite their huge size and capability, they still follow the path of the horse-drawn cart.
There is no new technology needed to build the vector neutral
truck; the novelty and innovation are in the arrangement
and combination of the components.
60-ton vector-neutral truck
A 650-hp engine drives through a mechanical transmission
transfer case and drive shaft to two axles with four tires each.
The fully enclosed operator’s compartment is located
amidships, facing inward perpendicular to the line of travel.
The 60-ton vector-neutral truck is 10.6 m long,5.2 m wide and
3.9 m high with an outside turning radius of 9.5 m.The dump
box has a heaped capacity of 35 cubic metres and is hinged
on the main frame.
400-ton vector-neutral truck
The vehicle has a 2700-hp power plant that drives through an
electrical drive system to two axles with four tires each.The
fully enclosed operator’s compartment is located amidships,
facing inward perpendicular to the line of travel.The 400-ton
vector-neutral truck is 19.9-m long, 9.1-m wide, and 7.5 m
high, with an outside turning radius of 17 m.The dump box
has a heaped capacity of 183 cubic meters and is hinged on
the main frame.
The calculated time required to stop the 400-ton or the
60-ton vector-neutral truck from a speed of 12.8 km/hr, and
again from a speed of 8 km/hr results in a time of 0.13 min per
haul cycle required to position for loading and dumping.
The distance and estimated time required for a conventional
truck to make two 180-degree turns, stop and reverse into
position for loading or dumping is longer.One turn manoeuvre
starts at 12.8 km/hr,the second manoeuvre starts at 8 km/hr.The
time to complete these manoeuvres is 1.6 minutes per haul
cycle for the 60-ton Terex, and 2.4 minutes per cycle for the
400-ton Liebherr.
The biggest dimensional differences between vector-neutral
and conventional trucks appear in overall length: 4.6 m for the
400-ton truck and 1.4 m for the 60-ton truck.This is caused by a
slightly longer wheelbase on the vector-neutral trucks and a
dump box that is longer than the conventional dump box.
The loading height of the 400-ton vector-neutral truck is one
metre higher than the conventional truck,but the two trucks do
have the same overall height. Loading heights on the 60-ton
trucks differ by only 0.2 m. There is a slight difference in the
turning radiuses, less than one metre for the 400-ton size, and
0.4 metres on the 60-ton version.Overall road width is the same
for both the 400-ton vector-neutral and conventional trucks.
The 60-ton vector-neutral truck is three-quarters of a metre
wider than the conventional truck.
There is also a difference in weight between the vector-neutral
truck and the conventional truck due to the addition of two
slew bearings to the major component list.This is partially offset
by the deletion of the Kingpin and front suspensions, not
needed on the vector-neutral truck.
The vector-neutral truck’s,eight tires share the same payload
and similar vehicle weight carried by only six tires on a conventional
truck.This means either smaller tires or a larger payload
when compared to the same sized conventional truck.
From a physical standpoint,the vector-neutral truck is able to
work alongside conventional trucks of the same capacity,with
little or no changes to ancillary equipment or roadways.
The vector-neutral truck uses the same major components
(i.e. engines, transmissions, tires and wheels) as conventional
equipment and thus would not require any special maintenance
services.
The comparison between the two different-sized conventional
haulage trucks and their haulage cycles and the vectorneutral
haulage trucks and their performances demonstrates
the advantages of this new design.
Mike Parsons, C.E.T., is proprietor of Parsons Design.
Readers
may contact him at 705-673-1232, e-mail: parsons@vianet.on.ca.
Web site: www.mikeparsons.ca.
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