This is a really small but functional wheeled excavator built with stud-less Technic pieces.
The core of this concept is the possibility of fitting the connection between fake piston engine in the rotating excavator tower and the wheels in the base along with differential and steering in such small scale model.
It's also about making a set that has wheels, steering and differential, turntable and a lot of gears plus a reasonable amount of Technic liftarms to play with and build different mechanisms and vehicles, but not a huge one and based on IP like existing kits with a lot of gears and mechanisms.
I'm generally not fond of making full showcase videos - I like building mechanisms with Technic, but making a video composition with good timing, music and descriptions feels like a chore/work to me. Below you can find feature footage so you can take a look at what interests you instead of scrolling through a lengthy showcase.
This model was built as a proof of concept with limited supply of Technic elements and my assumption is that LEGO team would be able to improve upon external aesthetics and some functional details.
The model has working excavator arm that is controlled with two knobs at the back. That's a lot of spinning, but it is a cool detail if you want a pose'able model on your shelf.
The steering knob on the top of operator's cab is connected with an axle going through the centre of the big turnable between the base chassis and the tower of the excavator. This axle then uses worm drive to angle and transfer steering towards front wheels. The worm drive use makes it so that small turns of the tower are negligible for the wheel steering due to gear ratio.
Around the steering axle in the middle of turn table, there is an old type differential frame that lets you put an axle through. This differential body is used as a shaft with two gears that transfer the drive through the turn table around the steering input axle. This lets this model have working piston engine in the back of the tower regardless of how the tower is oriented.
Final touch on this model is the inclusion of front dozer blade at the front and spring-snapping support arms at the back of the base like the ones in real wheeled excavator.
This model is a proof of concept showing how much fun mechanisms can be fitted within a small scale LEGO Technic model. The base chassis has one assembly step that might be hard for smaller kids as three smaller assemblies need to be held together while the additional reinforcing elements are attached from the sides, after which the construction of the chassis becomes fully rigid. Those sub-assemblies are pretty simple assemblies though, it's just that putting them together may be harder for smaller kids.
- built with stud-less Technic pieces
- detailed operator's cab interior with steering wheel, excavator arm control sticks and seat with armrests
- working knob-controlled excavator arm
- front wheel steering connected to the control knob on top of rotating excavator tower
- rear wheels with differential connected to piston engine at the back of rotating excavator tower
- spring-snapping support arms at the back of the base chassis
Why does it make sense as a LEGO Ideas set:
- has balance between fun gear mechanics, interior/exterior details and making enough structural integrity to support the weight
- contains multiple gears, wheels, cardan joints, actuators and a big turntable so it could be a new go-to mechanical set for MOC creators community
- the amount of bricks is similar to medium sets in contrast to other Technic sets with a lot of gears and mechanisms
- does not base on IP/trademark so again it won't require to license the IP
The model in a final kit could be made two studs bigger in each dimensions to improve upon accessibility of the build and for the production optimisation. Such decision would allow for potential use of slightly bigger wheels, maybe addition of a spring-snapping mechanism for the dozer blade, improving gear ratios for excavator arm knob operation and finally aesthetic detailing of the whole model.