42100 Liebherr PR 776 Dozer

An alternative model for 42100 Liebherr R 9800 Excavator

Designed and built by Eric Trax, instructions made by me.

Visit his Facebook page for more great models:


Model is completely motorized, with 6 motors (three C+ XL motors and three C+ L motors) and controlled by custom profile in Buwizz application.

Parts list in Rebrickable, Bricklink XML, Brickstore and versions can be found here:


Before you buy these instructions, please read the following really carefully.

– This model is not recommended for persons under 14 years of age and those with little experience in building more complex models. On other hand, you are here, because you have built the R9800, right? 😉

– This time wiring might give you give you a small headache. There are two C+ Hubs and 6 wires needed to be placed in the hull.

– All wires are color coded:

– The assembly is likely to take quite a bit of your time. It may not seem like a large model, but after adding tracks you will be surprised.

– To turn on bottom Hub press down left front handrail, to turn on top Hub press the connector above it.

– Also, there are several submodels that connects together, making one, large submodel. For example managing to fit whole blade assembly is tricky, because of several mounting points that has to be clicked togehter at the same time (actuator ends, arms etc).

– To comfortly play with this model, I reccomend to use fresh and unplayed batteries

Please be aware that this model will not work with LEGO App. We have created a special custom profile for Buwizz app, after buying you will receive a ZIP file with all files needed to run it in Buwizz app.

Instructions can be bought at Sellfy and Rebrickable:



The instructions how to use app are below:

– Model shown here uses custom sticker pack, made by Technic Projects.

It can be bought here:


Sample pages from instructions:

About the author

A 30 year old LEGO fan, who sometimes build something.