hinge hitch low loader - loadquip - hinge hitch low... · the hinge hitch is actuated by hydraulic...
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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
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
LOADING PROCEDURE:
Note: Wheel chocks not required for normal operation.
T 07 3839 2349
F 07 3832 3491
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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T 07 3839 2349
F 07 3832 3491
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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.
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www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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.
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PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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.
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PO BOX 247, SPRING HILL,
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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.
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www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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.
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www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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
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PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
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
www.loadquip.com.au
PO BOX 247, SPRING HILL,
BRISBANE, Q. 4004
2ND FLOOR,
457 EDWARD ST
