Shipyard transporter is a vehicle which can transport ship parts in shipyards. It isn’t the same as the modular trailer or SPMT that can carry up to 1000tons by only 1 set.
The Shipyard transporter has a larger working platform and higher Loading surface as shown.
The shipyard transporter became a lot useful in the transportation of heavy industrial equipment, vehicles and ships. Industrial facilities such as power plants, shipyards and factories often need very big delicate objects that re normally heavy.
The movement of such objects within the buildings or to the test locations becomes almost impossible through the use of conventional lifting equipment such as forklifts.
The invention of the shipyard transporter came about because of the following scenarios:
- The most commonly used method of lifting and transporting objects within industrial facilities was mainly through the use of cranes. The gantry crane was and to this day been used for lifting heavy objects through the use of a hoist attached to a trolley running in a horizontal format along the gantry rails. The gantry crane however could not suffice when lifting much heavier objects such as ships on a shipyard. The equipment is disadvantaged when required to lift big size, particularly high objects. Another challenge with the gantry crane is the maneuverability efforts. Lifting equipment in this category usually found in many industrial facilities is the overhead crane system. This works with beams usually mounted on the side walls of a building. For the overhead crane unit, the hoist mounted on a trolley carries the load as it moves along the beams. The main disadvantage with this arrangement is the inability to move the object from one yard to another especially outside the building past where the track system of the overhead crane extends.
- The shipyard transporter is great solution to the incapacities also realized with the use of very heavy capacity forklifts and trailers. These two need an extended space to operate from and a place for heavy point-loading on the ground surface during operations. These heavy capacity forklifts are usually on solid tyres or limited mechanically balancing suspension depending on the tyres’ compression for compliance to rugged operating surfaces. Very heavy capacity solid tyre trailers are restricted to mechanical equalizing suspension. That means that the provision maneuverability and compliance on congested floors and irregular floors is limited. These have sharply diminishing abilities for loads over 40 tons in weight.
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Table of Contents
1. Concept Development of the Shipyard Transporter
The need for transporting much heavier loads inside an industrial facility where objects are over hundreds tons in weight led to the development of the Shipyard transport, In Plant-Self-Propelled Modular Transporters (IP-SPMT).
These are low-profile deck self-propelled transporters with multiple axles and independent suspension axle assemblies basically used for carrying and transporting heavier loads up to hundreds of tons.
The IP-SPMT is basically powered through internal combustion engine-electric means and consists of 6-12 or even more on-center rotation assemblies of axles.
These axles can be steered independently through varying motor direction and speeds.
However, IP-SPMT devices and these other movers cannot suffice in certain applications owing to the fact that the wheels can overload the surfaces upon which they operate.
To address the issue, air bearings were proposed or the type where some special ground preparations is needed. Another proposal was the use of tracked type vehicles but these did not have maneuverability and also needed larger space.
Such scenarios presented a transporter that would address all these challenges and this is through the use of the Shipyard Transporter.
Here are the common specs for reference:
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2. Design and Construction
The successful and effective transportation of heavy objects over hundreds tons in weight requires a transporter with many track-axle assemblies and that is what characterizes the shipyard transporter.
The track axle assemblies have independent self-loading, suspensions and on-center axle rotation abilities.
Each of these track axle assemblies have hydraulic piston and a cylinder housing with the first and the second track units linked up on opposing sides of the frame of the axle.
The design configuration is of a transporter with track-axles meant to take very heavy loads.
More specifically, the transporter has multiple track axles each with independent suspension, a self loading and on-center axle rotation ability to enhance capabilities of carrying very heavy loads without interfering with the transport ground surface.
3. The Structure
The shipyard transporter is a multi-wheeled transport vehicle with capabilities of loading and carrying very heavy objects as it cross over uneven surface without torquing the load.
The structure contains a modular wheel unit with a low profile with attachments for equalizing the load exerted between each of the individual wheel units.
Specifically, the structural design is made in way that the axle assemblies do not result in contact pressures that lead to rutting in asphalt surfaces.
With this type of construction, there is no need to resurface the roadway following use or to make a replacement of the roadbed through the use of concrete surfaces meant to take up the wheel loading.
Essentially, the shipyard transporter can take up very heavy objects without exerting much contact pressure on the roadway and at the same time provides a high maneuverability level.
Each track unit for this track-axle assembly could include a side plate mounted pivot-ably to the frame of the axle, an idler axe and a driver axle attached on the side plate,
a gear box and an electric motor attached on the side plate, power transmission systems that extend between the driver axle and the gear box to rotate the driver axle,
and then an idler wheel as well as a driver wheel attached on the idler axle and the driver axle, respectively. Hydraulic motors are also used in this application.
Every track system of the track-axle assembly could also include a track belt fit for both the driver wheel and the idler wheel. A means of tightening the track belt such as a tensioner roller is also included.
A support frame for the track is mounted between the driver wheel and the idler wheel and again a track roller support assembly or a low friction pad well-mounted on the framework of the track support.
The track roller assembly could include a sensor that determines side loading on the installed track belt.
The design comes with a frame and load deck, a machine logic controls, a power compartment and electrical compartment; a hydraulic power system and several track-axle assemblies located underneath the load deck.
The shipyard transporter’s power compartment could include a generator, a combustion engine and a battery.
The track-axle assemblies of the shipyard transporter could also include an axle frame with a hydraulic piston and cylinder housing as highlighted in the design.
The transporter processor could include a dedicated machine logic controller to manage and control all the track axle assemblies.
On the other hand, the machine logic controller has a steering logic to laterally, linearly, rotationally and obliquely control the track-axle assemblies.
There is also a direction/speed controller that offers command signals to each of the track-axle assemblies and a suspension controller for lifting and carrying the load, lowering and raising the transporter and to establish and keep a desired travel height.
It is also used to provide a sequential load relief.
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4. Operations Modes of the Shipyard Transporter Parts
The controller for load relief of the shipyard transporter can decrease a fluid pressure inside the cylinder housing of selected singe or
a pair of track-axle assemblies to facilitate the transfer of the load unto the neighboring cylinder housings that are fully pressurized.
The cylinder housing for the shipyard transport could also be pivotally attached on the axle frame through a pair of trunnion pins that permit the track units to tilt in response to the laterally irregular surfaces.
The shipyard transporter suspension controller controls fluid pressure that acts on all the hydraulic pistons of the various track-axle assemblies.
This provides an interaction between various track-axle assemblies to travel through surface irregularities on the transporter’s line of movement.
On the other hand, the lift circuit of the transporter could be fitted with pressure transducers. The electrical section of the shipyard transport also includes a shore power supply.
The track-axle assemblies of the transport could also have a fluid pressure transducer in place, lift and angularity sensors, wheel direction/speed sensors and also track stress sensors.
Wireless, tethered or embedded interface for the user can can also be included in a shipyard transporter.
The innovative way of synchronous steering of the track axle assemblies possible with this configuration ensures the performance of a limited radius turning capability hence keeping the operations safe from tip overs.
When the travel steering gets to a stress limit point of side loading for each of the track assemblies, there is a way of stopping the transporter to facilitate the achievement of a closer turning radius to counter that effect.
This makes it possible to sequentially offload, rotate to a new direction of travel and loading each of the transporter’s track-axle assemblies again. At that position, the shipyard transporter can now move in a different travel direction.
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5. Hydraulic Systems and Control
- Hydrostatic drive system
The hydrostatic drive is a closed-loop system of hydraulics with a variable drive pump where the variable control is the electric proportional.
- Hydraulic Steering System
The hydraulic steering system on the other hand is an open-loop system. The open loop system has a variable pump used to integrate the load-sensing together with the pressure-cutting-off flow control capabilities.
The output flow of the variable pump is also adjusted based on the need of the load to save energy.
Through the use of the pressure-cutting-off flow control function, the utmost output pressure of the pump can be restricted in order to protect the system.
- Hydraulic Lifting System
The hydraulic lifting system together with the hydraulic steering unit has a common open-loop variable pump.
Hydraulic oil coming from the pump is supplied evenly to the lifting cylinder. This makes it possible to lift the platform at a leveled position.
- Hydraulic Cooling System
There are two system gear motors that are used to drive the fans to cool down the composite radiator. One of the pumps is used to supply the hydraulic oil under pressure to the system gear motors.
- Hydraulic Break System
The shipyard transporter achieves the brake function and the parking brake through hydraulic means where the brake cylinder pushes and releases the brake drum.
Inside the cylinder, there are springs that are used to keep the vehicle in the parking brake status in the absence of pressure oil inside the cylinder.
A manual pump is also part of the braking system and its main function is to release the brake should there be no power of the vehicle.
- Hydraulic Suspension
The hydraulic suspensions are categorized into wheel bogies with brake, wheel bogies without brake and wheel bogies with drive. Ideally, the hydraulic suspension consists of a bogie frame,
hydraulic suspension cylinder, rocker arm, axle with brake, or without brake or with drive, tyre and so on.
The gear shaft sleeve is welded on the frame of the bogie and the hydraulic suspension cylinder located between the rocker arm and the bogie frame.
The rocker arm is used for linking up and bearing the road. This setup creates the hydraulic suspension adjusting range of + or -350mm.
The motor and the reducer are attached to the wheel bogies that have drive and are use to give the driving force needed for the vehicle.
The wheel bogies that have been installed with brakes have axles with brake and have a brake cylinder on it that actualizes the parking brake and service brake for the vehicle.
The three different types of wheel bogies are all provided with mechanical stoppers to control and limit the maximum position and
make use of the minimum suspension cylinder stroke to control the lowest position normally used for vehicle transportation, replacement of tyres and also needed when repairing wheel axles.
The process of making a replacement of the tyres unloaded or on full load are as follows:
- Lift down the bogie with the tyres that need a replacement
- Shut off the suspension cylinder’s ball valve
- Lift up the entire shipyard transporter
- Make the tyre replacement
Once the tyre replacement is done,
- Lift down the entire shipyard transporter up to the lowest point
- Take off the locking pin
- Open up the ball valve on the suspension cylinder
- Lift up the entire shipyard transport to the recommended driving height
The recommended replacement tyre us the solid quality type 355/65-15/9.75, the most suitable option that can meet the loading bearing requirements of the entire vehicle of up to 1.1times dynamic loading.
The rims are of different types: one with the wheel bogie having a drive and the rim on the wheel bogie that has brake and that without brake.
By way of making adjustments to the hydraulic suspension system, the support system of the shipyard transporter can create 3 or 4 points of support to brig balance through the equal distribution of loads on all the tyres.
Additionally, this makes the transportation on the rugged road reliable and safe.
Each of the suspension cylinders is installed with 2-direction anti-break valve to cover up should the pipeline be broken.
The increasing flow will suddenly cause a differential pressure between the inlet port of the valve and the outlet port to block the broken pipeline. This measure is crucial in preventing the cargo from inclining to one side.
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6. Electronic Multi-Mode Steering System
The electronic compound multi-mode steering system is typically made of steering hydraulic pump, oscillating cylinder, proportional sandwich valve, angular sensor, rack-and-pinion steering device and the electronic calculating element.
The rack-and-pinion unit comprises oscillating cylinder cases, angular sensor, oscillating cylinder, rack and pinion among other elements.
The oscillating cylinder cases have the function cross girder and are welded with the frame with great manufacturability and enhance the reliability of the structure.
The angular sensors are well attached on each of the wheel bogie.
The moment the remote controller sends the steering signal, the electronic calculating element will respond by calculating the theoretical inclination or angle based on the steering mode.
This will the make a comparison with the feedback as provided by the angular sensor where the wheel bogie will calculate the amount of electric current of proportional sandwich valves to facilitate the control of opening.
Ultimately, the wheel bogies will be pushed through the hydraulic steering cylinder to get to the desired destination positions through the steering.
The Shipyard transporter can attain 8 steering modes: each wheel steering along, each wheel steering cross, front wheels stressing, rear wheel steering, diagonal steering along, diagonal steering cross, circle steering and rest mode.
It can also set other modes of steering based on the operation needs. The steering modes of the multi-coupling transporters are usually similar with those of a single transporter.
When the difference of the steering angle of the wheel bogie is more than 8°, the system driving the vehicle will shut itself off automatically. This is a safety configuration that stops the vehicle and sound an alarm.
The shipyard transporter is a transport mainly used in the transportation and movement of ships between shipyards or to their docking stations.
Most of these liftings and movements except by SPMT have mainly been done in-house. Therefore, the shipyard transporter is a designed in a way that can offer much more capabilities for weighty objects.
Additionally, the nature of the design does not interfere with the transporter’s travelling ground which has been a challenge with previous transporter designs.
Most of the in-built systems for the shipyard transporter are hydraulically controlled.
This is a detailed document with information about a shipyard transporter, its design considerations and structure and how it can optimally be used to produce the desire results in operations as would deem necessary for its use.