ETF HTX-380 Mining Truck.

[efferman]

oh my god, now it is a fact that i cant build this truck with my current parts. i have enough tires but other parts are empty after , well this....

beside of my insufficent count of some parts iam happy. the turning circle is exactly 1.35 meters from outside to outside and the tires are rolling fine without moving to side

[Pat-Ard]

I don't believe it... That looks so cool...I would be glad if I only could build stuff like that half as good as you...

Just WOW!!!

[KopMaister]

Dammit that's super-mega-foxy-awesome-hot!

[timslegos]

So many parts! I wish you would build a full one.

tim

[efferman]

oh, what iam happy that i have build a test chassis. Under load the wheelbase is too short and the mudguard collides with the axle behind and blocks the return tu the center.

[Feradin]

...Gigantic...

[otpi]

Nice project! I had a look at http://www.etftrucks.eu/, that's some heavy machinery porn

Would it not be easier to use a nxt and servos for steering? If you settle for the 5 axle variation you could use 1 servo for the first and last axle, one for the no. 2 and 3, and the last for the center axle. This way you could use the center axle as the fixed axle in for the ackermann geometry, unless you want to crab, then you'd turn all wheels 0-90 degrees depending on crab angle.

Speaking of Matlab; If you need a hand shoot me a message.

[efferman]

simple answer: four intelligent nxt bricks, 10 servos

would you pay for this?

[otpi]

No, no, what I meant was to link steering of 1st and 5th axles, 2nd and 4th, and center (3rd) by it self. This way you get away with 3 nxt servos and one brick. :)

[efferman]

but where is the sense to use nxt, if not to make crab steering possible?. and for this, every steering point needs its own servo

[otpi]

It's a compromise I agree since even one nxt is expensive. A more expensive compromise would be to have two nxt bricks and 6 servos. three for the left and three for the right side of the vehicle.

You'd have two steering modes: Crab steering which turns all wheels (turntables) the same angle; and regular steering which turns the front wheels opposite of the linked rear wheels, with the center axle fixed. Since the nxt servos measure angle you could maintain correct steering geometry over the entire range of angles.

The down side is that you'd have to return to center to switch modes (which would reverse the turning direction of either the forward or aft wheels). You could do away with this in a 3 axle version, such as the one you have, since you'd have one servo for each pair of axels (front, center and rear). Come to think of it that may be preferable? Do you have one or two nxt's around?

[efferman]

you know that the fifth axle has in normal mode an different direction to the first axle? how do you give them the same direction for crab steering?

Edited February 1, 2013 by efferman

[otpi]

Yes, that's one of the compromises. You would have to return wheels to center and reverse the direction using gears to switch between modes.

Just thinking out loud: For a 5 axle etf, do you think it is possible to turn the 4th using the angles of the 3rd and 5th, and some clever gearing to get 4th to turn. It should at least be possible to gear it such that the 4th gains 1/2 of the 5th and 3rd, i.e.:

• 5th at 0 deg, 3rd at 0 deg yield 4th at 0 deg
  
• 5th at 30 deg, 3rd at 0 deg yield 4th at 15 deg
  
• 5th at 30 deg, 3rd at 30 deg yield 4th at 30 deg
  

For a 3 axle version you could do with one servo for aft axle pair, one for center pair, and one for the front pair. You would have to forgo the ackermann geometry for the left right side, unless you also implement track rod for fore and aft steering. But then you would not be able to turn the wheels 90 degrees? This way you wont have to switch modes mechanically, only on the nxt brick.

Another way to arrange this is to have one servo for the center wheels, and connect left fore and aft to one servo, same for the right side. This require a gear switch to reverse the turning directions for crab mode. But you'd have correct steering geometry for all angles, but be limited to always turn about the center axle.

Sorry for all the ramblings, I just thought it'd be interesting to see a solution that did not require eleventy nxt's.

[efferman]

Gears are jumping over, so gears are not an option and ackermann is a must have for me. either a full programmable or a full mechanical steering system. thanks for your thoughts and maybe someone wants to try it out with my suspension system but myself is going the mechanical way.

[efferman]

the backbone, with the main steering system, is finished. the actual ldd file you can find %20etf-backbone%20von%20efferman%20auf%20Flickr"]here[/url].

[Rishab N]

oh my god, now it is a fact that i cant build this truck with my current parts. i have enough tires but other parts are empty after , well this....

beside of my insufficent count of some parts iam happy. the turning circle is exactly 1.35 meters from outside to outside and the tires are rolling fine without moving to side

How big is that and how much does it weigh?

[DLuders]

@ efferman: I'm not sure whether you are already aware of this (or whether you MOC will be using these or not), but Saberwing40k made a LDD File of the Lego Power Functions L-motor and Servo-motor, and posted it here. You can see how he built up the equivalent pinhole locations:

They represent Bricklink Part 99498c01, "Light Bluish Gray Electric, Motor 9V Power Functions Servo with Dark Bluish Gray Bottom".

...and Bricklink Part 99499c01, "Electric, Motor 9V Power Functions L with Dark Bluish Gray Bottom."

Edited February 2, 2013 by DLuders

[efferman]

on this picture its weight is 2500 grams, the width 305mm and the wheelbase is 350mm and the length overall is 650mm. the final mining truck will have roundabout 720mm wheelbase

@david

thanks for posting the link

Edited February 2, 2013 by efferman

[Paul202]

Holy crap, that's one heavy lego model.

[efferman]

indeed, hopefully one hard shock absorber per wheelpair is enough for the real model.

btw, a big step is done. the wheel pairs are attached, but not reinforced yet.

current part count: 3228

actual file: http://www.brickshel...entywheeler.lxf

bugfixes: little error in steering system fixed

Edited February 3, 2013 by efferman

[Edwin Korstanje]

And i was thinking that i am a liftarm maniak, but you olso .

Very nice chassis again Effe

[Brickend]

Is it possible to see the axle spacing in plan view?

[efferman]

this view?

[timslegos]

Thats one huge model, I would love to see it built.

tim

[otpi]

Gears are jumping over, so gears are not an option and ackermann is a must have for me. either a full programmable or a full mechanical steering system. thanks for your thoughts and maybe someone wants to try it out with my suspension system but myself is going the mechanical way.

Even with the all the gearing on the input side of your linear actuators?

Do you plan on implementing a system for crab steering? Won't the shorter track rod, that gives you ackermann geometry, get in the way of crab steering?