Sunday, January 10, 2010

Week TechVideo, 2010 #02 - Fully remote controlled pneumatic Excavator

Since we are all excited about the new 8043 LEGO Excavator, nothing more appropriate than another great Excavator to rejoice.

After some flaws and challenges (if you have been following it from facebook), Paul (Sariel) published yesterday his new pneumatic Excavator (a model from Volvo EC290C). It is a fully pneumatic excavator with a full remote control. It differs from almost everything else ever made before, because former similar models use to have a remote tethered by the pneumatic hoses, which houses the pneumatic valves and usually also the compressor, battery box, etc...

Thus one of the main challenges consisted to fit everything needed inside the superstructure, inclusive the electric command for each individual valve. For this Paul used the concept developed by Dmac, another LUGPol member (but that's a topic for a later opportunity...).

The model features:
  • 7x PF M-Motors
  • 1x 71427 motor
  • 3 pneumatic circuits with 8 cylinders total, for each of the arm 3 sections (boom, dipper and bucket)
  • Internal 4-pump compressor with integrated manometer

As usual, you may find all the construction details, photos at

This is to me, certainly the Holy Grail concept for a LEGO Technic Excavator! Pneumatic, fully remote controlled and with all the required elements on board.
There are certainly some issues requiring improvement in this model. It is quite unusual on Paul's models but this was a very difficult challenge and I think Paul wanted to finish at any cost in a reasonable amount of time, instead of delaying by going through a succession of heavy rebuilding steps. Nevertheless I guess this is not going to be the last Excavator in this class, we will see from Paul.


zimvaider said...

I love that excavator! The only thing that concerns me is the bucket looks quite out of proportion... or maybe it's just me.

Al said...

Just a shame he had to double up the pneumatics, know what i'm sayin ;^)

Al said...

Incidentally I built a similar one using one motor to drive everything (bar the pneumatics) via a gearbox that could operate both tracks and superstructure rotation independantly or simultaneously in any direction. To power the pneumatics I used one XL motor driving eight pumps, the power and performance was epic and quite realistic and there was almost no lag time to raise the arm, I highly recommend doing this. Anothing thing to try is limiting the air flow by clamping (but not completely closing) the air pipe between two appropriately space pieces so the arm doesn't drop down. With experimentation you'll find it quite easy to get it to come down at a realistic speed. This simple trick also helps to prevent it coming down during drops in pressure. That's how I did it in my model. Alternatively you can counter the weight of the arm by using shock absorbers or belts, so that with no pneumatics attached, the arm would "float". This also helps to prevent it coming down during drops in pressure. I still have it partially built, may post some pictures somewhere, gotta get a camera first tho 8^D.

Sariel said...

Thanks. I should mention that I've just learned that another fully pneumatic and fully remote-controlled excavator has been build by my countryman earlier. Here it is:

Al said...

Another brilliant excavator and a great example that pneumatics can be controlled smoothly but with added grace, power and realism.

TechnicBRICKs said...


Ok, added to the text one "almost", that solves everything!... :D

Anonymous said...

I think he could optimize performance if the primary arm was lifted by linear actuators while leaving the secondary and the shovel on pneumatic control. But that's easy to say...

still amazing machine to see it self contained. Nicely produced video as well.

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