|Dump Truck 10x4 (2009)|
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In the Netherlands, 5 axle dump trucks (Ginaf, MAN, Mercedes, Scania, Terberg) with a loading capacity of ~25m3 (~ 30 ton) are frequently seen because the Gross Vehicle Weight (GVW) in the Netherlands is 50.000 kg. Although not equipped with many technic functions, I decided to rebuild one in Technic LEGO® because it are impressive vehicles. And, children do like to play with dump trucks.
The model has the following technic functions:
3 axle steering with ability to lift the 3rd axle, working V8 engine,
differentials on both rear axles, power
functions head-lights and of course tipping of the tipping bed.
It took about 4 months to build this model, which was not very complicated, except:
3rd Axle lift: Although the 3rd axle is steered, it should be disabled from the steering mechanism when lifted. As well, an ' auto center' function was necessary to assure that the 3rd axle always will be always locked in 'straight forward' position when lifted, even when the 3rd axle wheels are not in 'straight forward' position when the lift is started. Both functions are realized.
Tipping: Ability to tip the '45-studs tipping bed' with significant load (DUPLO® bricks). First try with two linear actuators in parallel did not succeed, due to the huge force on the gear mechanism. Of course this has to do with the 'short range' of the linear actuators, which means that the linear actuators must be almost at the end of the tipping bed to assure at least a 45 degree tipping angle.... resulting in very high momentum. The solution was to use pneumatic power instead of geared powered. Therefore, the tipping is achieved by the usage of a parallel double pneumatic cylinder configuration.
Hopefully, LEGO® will launch in the future a 'long range' linear actuator.
Packed rear chassis: The 3rd axle lift mechanism and tipping mechanism are very closely packed within the model. It took some time to assure that the 3rd axle could be lifted when the tipping bed is lowered.
Initially, the idea was to make the dump truck fully remote controlled. However, during the project, two 'not enough space' issues occurred:
PF XL motor for driving: There
was not enough space left for a power functions XL motor nearby the
differential units for driving. An alternative, applying the XL motor under the cabin
would results in a very high (unwanted) torque on the drive-shaft axles and was
therefore no option.
PF medium motor for 3rd axle lift: The main problem was to enforce the 3rd axle to remain in lowered position when the truck is driven. In other words: a bumpy 3rd axle when driving a rough terrain was not acceptable. This means that (worm) gears could not be used, because they can 'rotate' a little when locked. A linear actuator could do they job, but did require - together with the necessary PF medium motor - too much space between the 2nd and 3rd axle, which was not available.
And, because it was obvious that a pneumatic system should be applied anyway for tipping, I decided to gave-up the remote controlled function.
Remote controlled 'pre-defined' ?!: Nevertheless, if the chassis of this truck is used for an other application (container instead of dump per example), it should be possible to replace the 'tipping' pneumatic cylinders with a 'driving' PF XL motor. Because the battery box is already available in the cabin, it should be easy to find a location for the 'steering' PF medium motor and a remote receiver.
The dimensions of this model are based on the Ginaf x5450 truck. The model is 66 studs long, and 18 studs wide. The building technique with stud-less is uneven which is the case for this model. Only exception is each mud guard which adds at every side an extra 1/2 stud. The reason is twofold:
All wheels are precisely ' in-line' with the mud guards. Very realistic
view of the cabin (17 studs width) whereof the 1st axle mud-board protrude 1/2 stud.
Practical: A perfect fit with the tipping bed which build is even.
The appearance of the truck is not
based on a particular truck brand. I tried to be as much as realistic by
applying details as: interior of the truck (dashboard, coffee machine, coffee
tanks, air compressors between the rear wheels, raise-able wind deflector,
spotlights, fire extinguisher, cabin doors open/close and more.
And yes, the cabin front does look very similar to the '8258 Crane Truck'... although I did not had the 8258 at the time of development. It appeared that the 8258 cabin height is according to the dimensions of the Ginaf x5450. And, eventually, most of these truck cabins do not differ very much from each other. So I decided to take the realistic 8258 cabin as a starting point, but with standard technic fairing panels.
Photo-shoot: Reconstruction of highway A2, Breukelen - Vinkeveen (The Netherlands)
The technic specifications of the 'Dump
Truck 10x4' model
* 5 axle truck, first 3 axles steered
* Turning cycle correction for 2nd and 3rd axle (with gears)
* 3rd axle can be lifted (pneumatic) and has an 'auto-center' mechanism
* Working V8 engine, including fan
* differential unit on 4th and 5th axle, interconnected
* Pneumatic tipping of tipping bed, consisting of 4 cylinders (2 in parallel)
* Headlights equipped with Power Functions LED's
* Different pneumatic circuits for 3rd axle lift and tipping
Non-technic functions are:
* Cabin doors open & close
* Cabin can be opened for engine access
* Raise-able wind deflector
* Dashboard with coffee machine and coffee cups
* Fuel tanks, air compressors and air filter units between the wheels
* Fire extinguisher, exhaust pipe
* Spotlights, flashlights, horns and airco-unit on cabin roof
The dimensions of the 'Dump Truck
10x4' model are:
* Length: 53 cm (66 studs)
* Width: 14,5 cm (18 studs)
* 3rd axle lift: 1 cm
* Tipping angle: 45 degrees
* Weight: 2,8 kg (including batteries)
* Number of parts: 2.454
* Development time: ~100 hours
* MLcad time: ~45 hours
A drawbar trailer was developed for this dump truck as well.
Technical inside (cut-away render):