Unimog U4000/5000

April 15, 2024 Leave a comment


Time for another Thirdwigg Unimog!

Instructions are available at Rebrickable.com.

I am now averaging about one Unimog a year now, so it was about time for me to make another one. The 1:21 scale truck is now fairly common, for good reason: it’s a playful size, it does not take too much space or too many parts, and yet gives plenty of space for functions. The popularity of the U423 led me to try a U4000/5000 version.

As I started designing, I wanted to have the standard functions: steering, a drivetrain, an engine. But once I placed these functions, I was left with a lot of space, and the truck was missing something to set it apart from all the other Unimogs. I added a simple two speed transmission, but I still wanted another function. After some looking at a number of photos of the U5000, I started noticing a common feature: a winch.

With a little bit of work, I was able to add both a front and rear winch. The front is mounted to the right of the engine with a HOG on top of the cabin next to the steering HOG. The front winch has a lock, which can be released by moving the step on the right of the truck. The rear winch is controlled by a HOG on the right of the truck, with a lock under the fuel tank.

In addition, I wanted some options for bodies, so I created two chassis lengths. The short wheelbase (U4000) has a 19 stud wheelbase, and the long wheelbase (U5000) has a 24 stud wheelbase. Both are similar in design, but have different bed lengths. The U5000 version also allows for both a standard, and four door cab. For the long wheelbase version, I built a fire truck box, and a long bed. For the short wheelbase version, I built a bed and a little camper. The camper features a bathroom, little kitchen, and a table to converts to a bed. Also, plenty of storage compartments are both inside and on the outside of the camper. Finally, a little tipper trailer is available. I built it to match the Dark Bluish Grey U4000, but it can be made in many colors.

I have created instructions for each of these versions, and each can be found at Rebrickable.com: U4000 SWB Truck, U5000 Fire Truck, U5000 LWB Truck, Trailer, Camper.

Just like the U423, I was very happy with how these trucks turned out. The Dark Bluish Grey version is my favorite. The trucks work well, and have all the functions a 1:21 scale truck should. I love all the functions; playing with the winch is great fun! The hood is a little too fragile for my liking, but it looks just like it should. Also, it was a great reason to finally build a camper, and this won’t be the last time. But first, we may need to do another Unimog in 2024. Stay tuned….

Happy Building…

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Hybrid Garbage Truck

January 29, 2024 Leave a comment


I had on my goals to complete another Garbage Truck for while. Now it is finally completed.

Instructions are available at Rebrickable.com.

I like trucks, and I like building them. Garbage trucks are the most interested to me. Not only do they look interesting to my eyes, but mechanically they have a lot going on inside of them. Naturally, recreating this out of LEGO fits well with the type of building I enjoy. When I started on this project, I settled on a couple of standards. First, it would be 1:21 scale, second, it would be manually functioned, and finally, it would be a rear loader.

I worked on this model differently than I normally do. Generally I design a crude frame, and place all the mechanical aspects on this frame, and slowly build out the rest of model until it is done. On the garbage truck, I worked on three sections on the build in tandem: the chassis, the body, and the compactor.

The compactor started first, and was the hardest to get right. I settled on a function that is controlled by one gear on the left of the truck. The gear moves the compactor door mount, and an interval resistance gear allows for movement of the compactor plate. The one gear controls the two movements. So when trash is added to the hopper, moving the gear extends the door down, pivots the plate, moves the door up, and then pivots the plate open again.

The body was started soon, and would need to work hand in hand with both the compactor and the chassis. The body would house both the extractor plate to push trash out of the truck, and the mechanism to pivot the compactor up to open. These two functions were simple to design, but what took the most time was making sure the body was strong to support the functions and the rear compactor, and to be smooth internally to make sure trash would not get stuck.

The chassis followed a more common building process. I started with the hardpoints like the wheelbase, length and engine placement, and slowly added in all the other parts needed. Right from the beginning I decided on a three axle chassis with axle 1 and axle 3 steering. Axle 2 would be the drive axle. As I built, it was clear there was a lot of extra space in the chassis. I added a little hybrid/EV drive to fill the space. The torque from the drive axle routes through a center differential that splits the torque between a fake electric motor and a fake piston engine. A resistance plate is added to the front of the piston engine so the torque will always start with the electric motor. When the speed increases, the torque will overwhelm the resistance plate and start using the fake piston engine too. It works just like a real hybrid engine. A selector is on the left side of the truck to select EV only where only the electric motors is used, or to select hybrid where both are used.

The truck and body are easily connected by four pins at the corner of the body. The cab tilts to make it easy to work on the engine. Finally, I created two small dumpsters for to hold trash. A small one and a larger one, and each fits with on the rear of the truck.

This ended up being one of my favorite models since the Ionos. The truck looks great, but packs lots of functional elements. The hybrid function works great and will be used again for another project. When I presented it at a show people could not get enough of watching the trash get cycled through the compactor. I always enjoy building a garbage truck, and I look forward to the next one I make.

Happy building.

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Mercedes 917

January 5, 2024 Leave a comment


A simple, but iconic truck.

Free instructions may be found at Rebrickable.com.

I am beginning to get more efficient in my builds. Many of the axles, drivetrains, and little mechanisms I have designed over the years are finding their ways into other builds. When I completed the Off Road Truck, it was clear there was a lot that could be turned into another build, rather quickly. The Off Road Truck had a great, strong chassis, a little fake engine, a working transmission, and a tipping bed. With a couple of changes it could turn into another truck.

I lengthened the chassis, and removed the crane. I added a longer bed and changed how the tipping function worked. The cab stayed the same for the most part, but I changed the grill to match the look of the Mercedes Benz 917 truck. Since much of the truck is the same as the Off Road Truck, this one still retains the I3 fake engine, the pendular rear suspension, rear wheel drive with two speed transmission, and the tilting cab. Two HOGs are on the roof, one for the steering, and one for the bed tipping function. The bed can tip in all three directions.

Sometimes these type of builds feel a little bit like cheating, as they use much of a previous build. But this little truck was a nice addition to my builds that is fun to play with and is easily built by others people who have a moderate Technic collection.

Happy building.

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