[TC29] Tracked Bucket Truck

[lmdesigner42]

Hi everyone, my idea for the TC29 contest is a tracked bucket truck similar to the one below. The plan is to have six motorized functions (2x driven tracks, outriggers, 3x boom movements) using a distribution gearbox à la 8043. White would be fine for a colour scheme, but it's a tad boring, maybe purple and yellow will work?

So far, I have a rudimentary tracked chassis with 3-bogie suspension. The 3x19 frames are placeholders, but the width is correct.

I have a good start on the distribution gearbox, the orange shaft drives a worm gear to move the changeover catches back and forth. It's going to be fun routing the coaxial driveshafts to go under the turntable :).

[Paul B Technic]

Nice work so far and this is a great idea.

[lmdesigner42]

I made some more progress on my entry, the distribution gearbox is now finished. The left and right outputs on the motor side (LBG 16t gears) drive the left and right tracks through the bevel gears and brackets at the other end of the assembly. The central output on the motor side will drive the outriggers via the red axle connectors. On the non-motor side of the gearbox, the central and right outputs are transferred concentrically up through the turntable to operate the boom. Finally, the last output, the isolated red clutch gear on the left, will drive the turntable. This setup allows the turntable and boom bending to be operated together when all three driving rings are on one side of the gearbox, with the tracks and outriggers on the other side.

Now the next step is to put a sturdy frame around all of this to mount the tracks and turntable.

I also have a rough draft of the boom done. It would be nice to give it a boxy cross-section like the real machine, but it's hard to do at this scale due to the size of the large linear actuators. At least the range of motion is pretty good.

[Paul B Technic]

That is coming along well.

 

[Teo LEGO Technic]

Looking great! The solution with the red clutch and clutch gears to transfer two functions through the turntable reminds me of the LEGO 8043 excavator, still one of my favourite sets ;)

[lmdesigner42]

I finally have a bit more progress to report. I added a bit more structure to support the turntable, and a rotation mechanism using a worm/8z gear combo. More reinforcement is needed, though, the tracks are only attached by pins. There's very little space to add a proper chassis around the gearbox, but on the plus side, the narrow width means that the bending stresses are already lower.

The arm has also been lengthened and updated with a more efficient actuator placement and a 4-bar linkage for a wider range of movement. It reaches pretty high, even without the bucket.

Finally, a simple video to demonstrate the motorized functions. I'm happy to report that everything spins the right way!

 

[lmdesigner42]

The outriggers are all done. They're not strong enough to actually lift the vehicle due to the linkage geometry, but the folding/unfolding range is pretty good. I also added a few more parts to finish the bucket arm and start on the bucket itself. If I hurry, I think I can get the rest finished in time.

[2GodBDGlory]

Looks like some good progress!