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1.0 INTRODUCTION
Various different types of tracked machines are used on mine
sites; theseinclude dozers, drills, and excavators. Tracks are not
designed to travel longdistances and the tracks suffer very high
wear if a machine has to be drivenmore than hundreds of metres at a
time. Off-road Low Loader Trailers areused on mine sites to move
these large pieces of equipment. The low loaderstypically have
pneumatic tyres and can be driven for long distances
withoutdamage.
The key features required in a low loader are ease of loading
and unloading,load capacity, safety and low maintenance. An
off-road low loader isdistinguished primarily by its axle load
capacity and size. On-road low loaderscomply with road regulations
in terms of width and axle rating, but off-roadmachines do not need
to comply with the on-road rules as road widths onmine sites are
usually much greater, and axle capacities much larger than
forroad-going vehicles. Several different types of off-road low
loaders exist.
HINGE HITCH LOW LOADER
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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2.0 GENERAL DESCRIPTION
The Hinge Hitch Low Loader is a rear-loading heavy equipment low
loader,with a unique method of pivoting the hitch to permit loading
on a fixed, inbuiltramp at the rear of the machine. The hitch
action is particularly simple. Whenactuated, the hinge hitch
arrangement allows the front of the deck to beraised. The deck
pivots about the low loader wheels, in turn lowering the rearof the
deck to the ground. The hinge hitch is actuated by hydraulic
cylindersand is positively located in place by locking pins driven
by hydraulic cylinders.
During this pivoting action, the low loader is secured by the
park brakes of theprime mover and trailer. This means the trailer
will be safely secured fromunexpected motion during the entire
loading and unloading cycle. It ispossible to complete a load or
unload cycle in about 5 minutes, with themajority of time being for
the manoeuvring of plant onto or off the deck of thelow loader
trailer. The speed of the hinge hitch motion has been
deliberatelyset low to minimise any safety issues relating to
moving large masses.
For loading and unloading, the tilting motion is controlled via
a wirelessremote control unit. By allowing the operator to operate
the tilt from within thecab of the payload item, there is never a
need for the operator to walk on thelow loader deck when tilted.
The tow unit shown is a Caterpillar 785, howevera Caterpillar 777
would generally be suitable for the 150t payload.
There has been considerable effort applied to the design of this
machine, withthe key priorities being high reliability and
maintainability. The use ofCaterpillar parts has been maximised in
the design. This improves theavailability of spare parts and
ensures a quick turnaround in the event thatthere may be parts
required for maintenance purposes.
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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LOADING PROCEDURE:
Note: Wheel chocks not required for normal operation.
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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150t HINGE HITCH LOW LOADER SPECIFICATIONS
Model 1 HH150
Rated Capacity 150 tonne
Prime Mover Caterpillar 785 (modified for haulage) 2
Prime Mover Tyres 33R51
Trailer Hubs Caterpillar 785
Trailer Tyres 33R51
Braking System Caterpillar Oil Cooled
Overall Length 31.0 m
Width across tyres 10.0 m (6.7m across prime mover tyres)
Max Speed (unloaded) Subject to Prime Mover
Max Speed (loaded) 3 Subject to TKPH
Max Ramp Slope 12.3% (Gross)
Max Tyre Pressure Required 116 psi
Typical Loading Cycle 5 minutes (estimate)
1. Various load capacities and configurations available. Larger
or smallercapacity machines are available.
2. The low loader can be adapted to other tow vehicles.3. Max
speed automatically reduced based on load. This can be configured
to
site requirements, depending on tyre TKPH demands.
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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Ap
pro
x.3
10
00
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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3.0 MACHINE CAPABILITIES
3.1 Performance
The Hinge Hitch Low Loader uses a 3 axis hitch on the prime
mover whichhas the dual benefits of allowing the payload weight to
be partially applied tothe prime mover, and also moves the towing
point to between the primemover axles rather than behind them. The
key to the success of this machineis the ability to get weight on
the prime mover axles for traction and to preventjack knife events.
This is an advantage over low loaders that have the hitchpoint
behind the drive axle of the prime mover.
The configuration of the Hinge Hitch Low Loader is intended to
provideenhanced manoeuvrability. The trailer axle is positioned
such that the primemover can execute a U-turn at its minimum
turning circle.
3.2 Braking System
The low loader utilises Caterpillar 785D front hubs with 33R51
tyres. Allwheels are braked with oil cooled disc brakes, fully
integrated with the primemover braking system. This is a very
similar system to that used in manyarticulated coal haulers in
Queensland, and to systems used in our other lowloaders. It is a
very simple and robust braking system, which draws on
coolingcapacity that is already available in the prime mover and
which wouldotherwise be under-utilised. The pivot geometry allows
the tilting to occur withthe trailer park brake engaged.
Safe braking of any mining machinery requires absolute
reliability andrepeatability and speed of operation in emergency
circumstances. The triedand tested brakes used in Caterpillar
trucks are highly reliable, fail safe, andfast-acting, particularly
if the actuation system uses no air - such as for theHH150 low
loader. For these reasons, they are used on the low loader.
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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On the Loadquip Hinge Hitch Low Loader, the prime mover brake
demandpressure is measured, and a proportional oil pressure signal
is sent to thetrailer brakes. The Caterpillar service brakes on the
low loader are preciseand highly controllable, and the system is
virtually instantaneously linked tothe action of the service brakes
on the prime mover. The trailer’s Caterpillarpark brakes are also
precise and highly repeatable, as they are spring appliedand
hydraulic release. This means that with any failure of the park
brakesystem, the brakes will be engaged owing to the energy stored
in the parkbrake springs.
3.3 Payload Items
The machine is designed around carrying a 150 tonne drill, with
the AtlasCopco Pit Viper-271 and Pit Viper-275 among the models
currently beinghauled by the Hinge Hitch Low Loader. In general
most other payloads up to150 tonnes are easier to accommodate
because they are less restricted inwhere they can be parked on the
deck. There are many other items of siteequipment that are also
currently being hauled, including Caterpillar 992wheel loaders,
dozers and excavators.
4.0 MECHANICAL
4.1 Hydraulics
The low loader uses industry-standard hydraulic components,
fittings andhoses in a conservative design for a long period of
trouble-free operation.Extensive use is made of filters, relief
valves and limit switches to protect thesystem.
Hydraulic cylinders are used to tilt the deck of the low loader,
with the floatheld in place during travel by locking pins, driven
in place by small hydrauliccylinders. Power for the tilt and lock
cylinders of the low loader comes fromthe hoist pump on the prime
mover. The tilt cylinders incorporate pilot-operated check valves
to ensure that the mechanism does not collapse in theevent of a
hose failure.
Some low loaders require disconnection of the low loader from
the primemover when loading or unloading, as they are loaded from
the front of thefloat. This can introduce contaminant into the
hydraulic system, and therepeated making and breaking of electrical
connections can introduce asource of maintenance issues into the
float. Our floats are permanentlymounted on the prime movers, and
there is therefore no need to make andbreak hydraulic and
electrical connections.
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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4.2 Lubrication
The grease metering system on the prime mover is used to
lubricate the fewpins on the trailer through flexible hosing over
the hitch. The hitch pins anddeck tilting pins are lubricated by
this means.
4.3 Ramp
The Hinge Hitch Low Loader has a flat deck top that tilts to
form the loadingramp. The angle of the ramp is 8.0 degrees with the
ramp on the ground. Thefact that the ramp has no angle change means
that loading machinery isparticularly easy, with no need to climb a
steep section of ramp, and then rollover onto a flatter section of
deck.
The first 2.5 meters of the deck/ramp is steel and the balance
is F17 gradetimber. The timber is 125 mm thick and 200 mm wide
ironbark. We use thehighest grade of hardwood, so the timber is the
strongest selection we canchoose for the application. The timber is
retained by steel frames, and toreplace any, it is a simple task of
unbolting a section of frame and insertingreplacement timber.
4.4 Access Systems
The primary access to the low loader trailer itself is via a set
of retractable“self-levelling” stairs, located on the right hand
side of the deck. These stairswork on a parallelogram principal so
that irrespective of the height of the stairsat the time, the step
treads remain parallel to the surface of the deck. Thestairs can be
operated using controls located at ground level and at the top
ofthe stairs.
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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The motion of the tilt cylinders is interlocked to prevent
machine movement ifthe stairs are not elevated to their retracted
park position. This is to preventinadvertent damage to the stairs.
Also, interlocks prevent travel of the primemover if the stairs are
not in their retracted position.
4.5 Design Matters
Our trailer floats are designed with the utmost effort to meet
or exceed allrelevant standards in terms of structural and
mechanical requirements. Weadhere strictly to the Australian
Standards both for design and manufacture.
We are aware that our floats may sometimes be a little heavier
than others ofsimilar capacities, but the extra weight is due to
the attention we place onmeeting the requirements of the standards,
which are not in fact onerous, butneed to be followed carefully and
rigorously. The capital costs for our floatscan therefore exceed
that of other suppliers, but we are certain that ourwhole-of-life
costs are lower.
Part of the reason we are certain about the integrity of our low
loaders is theeffort placed on understanding the loading situations
involved, and thenapplying the loads in appropriate combinations in
the design of everycomponent. Our knowledge of load cases comes
from many years of sitestrain gauge and accelerometer measurements
of mobile mining equipmentsince the late 1980’s when CMP Engineers1
was formed.
1 Our engineering design company.
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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More recently, we have carried out site strain gauging and
accelerometermeasurements on each type of low loader we have
designed and built. Thisexperimental work has verified, and allowed
us to refine, the load cases used.If companies are carrying out
designs of low loaders without suchfundamental test data being
collected, there can be no certainty about thesuitability of the
design load cases.
Considering the data that we have collected, we are certain that
companiesthat have not carried out strain gauge and accelerometer
testing of theirequipment will underestimate the dynamic loads that
occur in normaloperation on a mine site. A potential purchaser
should query the supplier as tothe extent of their strain gauge and
accelerometer testing of their equipment,targeted at assessing
appropriate load cases. If they have never carried outsuch tests,
their equipment is likely to be under-designed for fatigue loads
ormaximum load cases. We know that with the exhaustive testing that
we haveconducted, our equipment is designed with the highest
integrity.
Careful design means that weld repairs will rarely be required
on ourmachinery unless there has been some abuse or accident on
site (e.g.handrail damage or similar). The floats are not
over-designed, but areintended to accommodate a range of unusual
load events that might occur onsite, including but not limited to;
applying full rimpull to a bogged low loadercaught by one wheel,
loading the payload off centre (sideways and fore-and-aft) then
being subjected to exaggerated (but possible) dynamics
fromirregularities in the road, emergency braking events while
fully loaded and withfailure of either the prime mover or the
trailer brakes, jack knife events, severevertical dynamics, very
tight cornering, brakes dragging and more.
The load cycle spectrum for a vehicle of this type, which is
infrequently loadedto its rated capacity, dictates that maximum
load events dominate the designcriteria and not high cycle fatigue.
This contrasts with a coal hauler forexample, which is typically
loaded close to its rated capacity on every cycle.
As accumulation of “fatigue damage” is relatively slow, the
float life will be farin excess of 20,000 hours, as shown by a
consideration of fatigue issues.
It should be noted, as a testament to CMP Engineers' experience
in this area,that using the same design techniques, many of the 220
and 160 tonne coalhaulers that we designed, achieved well in excess
of 80,000 hours service,despite relatively severe fatigue
loading.
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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Finite Element Stress Analysis of trailer. Viewed from under the
front LHS.
5.0 ELECTRICAL AND CONTROL
5.1 Electrical System
The spot and work lighting, brake, turn and reversing lights,
operationalbeacons as well as the reversing alarm, are all directly
wired to the primemover using harnesses and terminal boxes all
constructed to appropriatemine site standards. The electrical
systems are schematically and physicallysplit into “Lighting” and
“Control” circuits, with the latter all passing through thePLC.
All lights are normally LED’s, but we are able to supply HID's
if preferred.
Cameras may be added and wired to a display in the cab if
required. Thiswould allow the operator to scan back over the deck
of the low loader andalso to view behind the machine.
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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5.2 Control System
Loadquip has designed and implemented the complete control
system andgraphical user interface (GUI) for the Hinge Hitch Low
Loader, interfacingsuccessfully with the prime mover to provide a
fully integrated solution. Thecontrol system primarily uses IFM
Effector and Caterpillar components, andhas been designed with
user-friendliness and safety as principalconsiderations.
The hydraulic systems (including access stairs, tilt cylinders
and lockcylinders) are all controlled through a pair of IFM
Effector PLC’s, one mountedin the control cabinet, which is located
on the low loader deck at the front ofthe machine, and one on the
prime mover behind the cab. All of thesefunctions are interlocked
with the park brake of the prime mover and thetransmission, so that
it is not possible to move the unit unless all hydraulic
andelectrical systems are in a condition where it is safe to move
the machine.
The PLC program provides extensive diagnostic reporting and
systemintegrity checking. It also controls the selection of gear
limits, so that when thetrailer is loaded, the transmission control
is not permitted to select gearsoutside the current limits set by
the program. The presence of a load issensed by microwave detectors
mounted on the trailer deck.
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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The primary means of operation is via a simple six button
wireless remotecontrol unit, which includes a “deadman” switch. The
remote control unitallows the operator to control the low loader
from a safe location. The lockingand tilting functions operate at a
single slow speed. The speeds areconfigurable to suit site
requirements.
The control cabinet, located on the low loader deck at the front
of themachine, is only used when the operator is performing
maintenance orcommissioning work on the machine. The control
cabinet contains an IFMHMI2 Display, which provides feedback from
the machine and notification ofany warnings or error messages. The
control cabinet display can also be usedby suitably qualified
personnel to operate features of the low loader formaintenance
purposes, including operating any hydraulic functionindependently
of any other.
2 Human Machine Interface
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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The second IFM Effector HMI Display, located in the cab of the
prime mover,does not offer any control capability of the system, as
it would not be a safepractice to operate the low loader from the
cab, where visibility to the rear isrestricted. The display in the
cab is strictly used to indicate the machinestatus to the operator.
The cab display in conjunction with an audible alarmnotifies the
operator of any warnings or error messages.
Emergency Stop buttons are provided along the side of the low
loader, whichshut the prime mover engine down if required. Audible
signals alert theoperator of normal or abnormal operation.
We have sufficient sensors to provide appropriate warnings of
high or lowpressure events, and high or low temperature events. Low
pressure mayindicate a hose burst, and of course high pressure may
result in damage. Hightemperature may also indicate a system
problem, but we also detect lowtemperature. Low temperature can
result in higher viscosity cooling oil, and inthis case, we reduce
the oil flow to the trailer brakes until the oil heats up, sothat
back pressure on the brakes does not lead to problems with
theCaterpillar brake duo-cone seals. Any unsafe conditions either
produce analarm or prevent operation. Interlocks prevent movement
of some parts of themachine unless other elements are in a safe
condition, such as movement ofthe prime mover if the trailer stairs
are down, or if the tilt cylinders are notlocked in their travel
mode. We have a large number of clear andcomprehensive diagnostics
that are displayed on the operator’s screens toassist warning or
identifying any problems.
An additional option that can be considered is a connection back
to Loadquipvia a modem. This would enable Loadquip to diagnose
issues that might ariseon site. This can be accomplished if a modem
and associated software wereto be installed on the low loader.
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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6.0 SAFETY
All relevant codes and standards are strictly adhered to, so
that safety ismaximised. This allows proper, safe retardation when
descending ramps, aswell as ensuring safe braking in emergency
situations. The service brakepressure demand by the operator is
sensed and the control system operates amanifold to apply the
correct proportion of pressure to the trailer brakes. Oilpressure
actuation results in faster response times than if air were to be
usedas on some low loaders, and leads to safer operation as the
risk of jack knifeis reduced. We are able to control the relative
braking effort of the trailer, fromthe loaded to the empty
situation, so that optimal braking will occur withminimal risk of
jack knifing. When the trailer is empty, the trailer braking
effortmay be reduced (not always necessary) so that the trailer
wheels will not lockup.
During unloaded operation the low loader is able to travel at
the normaloperating speed of the prime mover. During loaded
operation, the higherprime mover gears will be locked out to limit
the speed of the machine. Thisnot only ensures the unit continues
to operate within its tonnes-kph (TKPH)rating for the tyres; it is
also a safety enhancement, to ensure that speeds arekept to a safe
level when the machine is loaded.
Interlocks are provided to minimise the risk of unsafe acts that
might occurthrough operator error.
T 07 3839 2349
F 07 3832 3491
[email protected]
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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