Silo Truck (2017)


Building instructions (PDF)
(541 pages)
Example instructions (PDF)
Parts Inventory:
(2.835 parts)

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Manual Controlled

Finally - in October - I was able to present my 'contribution' to the 40 yr anniversary of LEGO® Technic. This time a mobile Silo Truck that I had several years on my wish-list to develop. I never started to design this truck earlier, as I was convinced that a 'full 90 degree' tipping of the silo platform required the so-called 'long pneumatic cylinders' (11 studs long instead of 5 studs for the standard cylinder). More about this later.

As mentioned, the model has a pneumatic system for loading/unloading the silo (5 cylinders, 24 pneumatic tubes), including a pneumatic pump driven by a Power Functions M-motor. That same M-motor drives the tilting of the cabin (2x mini Linear Actuator) or the extension of the rear outriggers (2x mini Linear Actuator) depending on the switch box selection. Manual functions are driving & steering, as well extending the rear bumper, necessary due to the overhaul of the silo.
Both rear twin-wheels have differentials that drives a 8 cylinder fake motor, a large fan in the bumper and 2 mini fans (tan gears) behind the cabin grille.

Fun part is that both seats in the cabin can be pushed down to be able to unfold the driver's sleeping bed. To be honest, I never saw a sleeping bed in such a truck, but found it nice to make :-)

Last but not least: the silo bucket can be open/closed (mini Linear Actuaror). It is really fun to have small LEGO® 1x1 plates popping around by opening the bucket.













The technic specifications of the 'Silo Truck' are:
* Manual controlled steering & driving
* Steering on 1st and 2nd wheel unit
* Double differential unit on rear axle
* Working V8 engine with 3 fans
* Full pneumatic system for loading/unloading; operated by
  a Power Functions M-motor driven pump
* Automated cabin tilting and outriggers extension; operated
  by a switch-box and the Power Functions M-motor
* Manual extension of the rear bumper

Non-technic functions are:
* Cabin door open & close
* Seats can be folded; to unfold a sleeping bed in the cabin
* Raise-able wind deflector
* Cabin grille open & close for mini fans access




Details applied:
* Cabin interior with seats and dashboard, and coffee machine
* Fuel tank
* 4 Spotlights, flashlights, horns and airco-unit on cabin roof
* Fire Extinguisher and exhaust pipes
* Air compressors between rear wheels

The dimensions of Silo Truck:
* Length: 56 cm
* Width: 14,5 cm
* Height: 22,5 cm
* Height with full raised silo: 34,5 cm
* Weight: 3,2 kg

* Total number of parts: 2.835

Photo-shoot (The Netherlands):
* Industrial Area A'dam Rijnkanaal, Breukelen & Loenersloot




Technical inside (cut-away render):



Bottom view:
Clearly visible are the rear twin-wheels with differentials and the drive-train to the front of the truck. Notice as well the pneumatic tube routing, especially the 'light bluish gray' ones between the 3rd and 4th twin-wheels at both sides. These pneumatic tubes do come from the twin-cylinders and are used for extraction / unloading of the silo.



Simultaneously operation of 2 pneumatic 'twin-cylinder' stages
The silo tipping is done in 2 stages. both operated simultaneously. The 1st stage is the traditional tipping of the platform with a twin-cylinder setup, nothing unusual. However, this 1st stage is connected on a 'sliding unit' in the truck's chassis! This sliding unit is driven by 2 horizontal cylinders that do 'push' the 'sliding unit' to the rear side of the truck; the 2nd stage. The beauty of this solution is the fact that this pneumatic system - both stages are connected to the same air in/outlets - balances itself in the force needed for extraction (horizontal and diagonal).
Why such a solution? This has all to do with the short distance (only 6 studs) between the platform's rotating point on the truck's chassis, and the mounting point of the 'twin-cylinders' on the platform. Simple said: the shorter the distance, the more force (momentum) is needed to tip the platform. In real life, cylinders do have a long stroke and much more force as the cylinder extraction is based on oil (un-compressible). In LEGO®, 2 flaws needed to be addressed; the short cylinder stroke and extraction based on air (compressible).



The silo itself was first developed in the program MLcad (CAD/CAM), so that I could calculate the overall weight of the silo. After a couple of redesigns the weight downsized from 850 to ~685 gram. Not much, but enough in the LEGO® scale!














The Silo Truck has many functions that make it really fun to play with. It takes a little time to be experienced in controlling the pneumatic switches to unload/load the silo, but after this you will be able to seamlessly operate them. Kids do love the ability to load the silo with little LEGO® parts and carefully open the bucket to have the parts all falling on the floor.
But even adults do like the silo truck, as I experienced during my exhibition on LEGOworld 2017 in Utrecht, The Netherlands. They reward the details on the truck and are mostly surprised that I was able to 'squeeze' in the ability to slide-out the rear bumper...























Sleeping bed inside the Cabin (Blakbird render):
Both seats in the cabin can be folded down to be able to unfold the sleeping bed. On the mentioned LEGOworld exhibition I was informed by a truck-driver that these kind of trucks do have sleeping beds as well (instead of what I thought)!