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A work in progress version of a 400 ton ETF truck. More info soon.

etf1s.jpg

Edit: some quick stats: 28 wheels, 14 L motors, 14 turntables, and 2438 parts as of right now. So, yes, it's really big.

When I started this project, it was smaller, scaled down to the only type of wheels I had the right quantity of. Much to my dismay, they were far too wide for scale. I tried literally every other tire in my collection, and got the same result, except for these tires. Even so, building the axles was a pain, I'll tell you why tomorrow.

Update: The axles were a major pain in the butt to build because of the fact that I had to include a differential in a module only 5 studs wide. However, this first iteration (shown above) was not strong enough, or geared down enough. So, I modified it, keeping the same torque tube design , but with the c bracket turned on it's side in order to accomodate portal axles. I also moved the motor from on the axle to a spot within the chassis. My model is currently roughly the same size as the one efferman is making, but since I have more motors (14 versus 10) and hopefully less weight overall, mine will be far more powerful. It also helps that these motorcycle tires are very, very grippy.

The chassis was also updated, with the frame rails now being 5 studs apart, providing room for the steering servo motor, and steering reduction gearboxes.

etftruck2frames.jpg

Also shown in this picture is the power module, with 6 receivers. 4 of the six will be slaved together, and provide power to the L motors. the remaining 2 will control the rotation of the bed, the tilt of the bed, and trafficators. Yes, it's going to have turn signals, and likely flashing warning lights. And, thanks to the fact that this model has a lot of internal room, I can include several engines, likely two supercharged v8s

The red beams on the chassis merely mark the outlines of the cab and dump bed, and will disappear by the time this is finished. The bed is currently in the prototype stage, as I am still working on the bed lift, and how the whole shebang is going to connect to the chassis.

March Update: This project is moving forward, albleit slowly. The mechanism for the turn signals is complete, but I have no photos. I'm actually building the truck as 3 sub models (the front, the rear, and the dump bed), due to the fact that the computer can't really process LDD models above 2500-600 parts.

The engines have been incased, and will be lit from below.

etftruck2frame3s.jpg

P.S. Does anybody know if you can slave an M motor to the same channel as the servo motor, and have the M motor continoulsy rotate even if the servo stops?

And, it's update time.

I've started on the cab, which will have seats, and house the trafficators.

etffront.jpg

No, the yellow and black colors aren't a mistake. Those will be the final production colors.

Rear view:

etffront2.jpg

this view shows the trafficators. The bottom motor is slaved to the steering channel. (I hope that it is possible to do that with an M and servo motor.), and the top motor is slaved to the drive mechanism, giving the model flashing warning lights. If you all are wondering what happened to the rest of the truck, I had to divide up the model so that the computer would stop freezing.

The dump bed has also been rearranged, and has the linear actuators, but not their drive motors or shafts.

dumpframe.jpg

dumpframe2.jpg

Still to do:

Finalize dump bed frame.

Finalize turntable connection, and add motor.

Add motors to control bed lift.

Add bed front and back walls, and dump gate.

Finish cab.

Mount Trafficators

Finish bulking up frame.

Colorize.

Real life testing.

Make instructions.

So yeah, lots to do, since this is a school project, I can afford to work on this a lot. Should hopefully be done by late April/ early May.

Edited by Saberwing40k

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Very futuristic looking truck! Power Miners does Technic (I'm actaully working on thing like this myself)

etf671cweb.jpg

But I think you'vee chosen the wrong wheels though? How about 20 Unimog wheels instead?

Would be killa (and expensive to boot) if you do it in lime :thumbup:

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I think the Unimog tyres are proportionally too wide, meaning that to allow the axle bogie to rotate 360 degrees, the bogies will have to be spaced unrealistically far apart.

The old 24 x 43 seems proportionally the better tyre, but maybe not tall enough for the scale required.

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But I think you'vee chosen the wrong wheels though? How about 20 Unimog wheels instead?

Would be killa (and expensive to boot) if you do it in lime :thumbup:

Nope, Unimog wheels would not work. See below. And it's probably going to be gray and white, or yellow and black, instead.

I think the Unimog tyres are proportionally too wide, meaning that to allow the axle bogie to rotate 360 degrees, the bogies will have to be spaced unrealistically far apart.

The old 24 x 43 seems proportionally the better tyre, but maybe not tall enough for the scale required.

Correct, they would be far to wide. Even with the narrow tires, getting the axle to be that small was a bear. 24 x 43 tires are still to wide, and too uncommon. I can buy these wheels and tires from Lego Direct, on the other hand.

Okay, all that aside, I need some help. I need to test the design of the axles in real life, but I don't have any L motors. If anybody has a spare L motor and wants to help, just download the file attached to this post. Also, I need a better way to connect the springs, so could you all help with that and post pictures in this thread when done? Also, please ask if you want to do this, so I know who's involved and doing what.

P.S. The first post is being updated with more details.

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i can test it if you want

where is the file?

Oops, I forgot to attach it. It'll be attached to this.

I may or may not have forgotten to put a u joint in the torque tube joint, but that should be easy. Okay, test away!

Also, and this is for everybody, I need a steering system. Does anyone have any ideas?

etfaxle.lxf

Edited by Saberwing40k

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Could you copy the 8043 slew drive and then convert it into a horizontal drive shaft and then gear it down to the motor?

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Could you copy the 8043 slew drive and then convert it into a horizontal drive shaft and then gear it down to the motor?

Do you have any idea how hard that would be? Oh wait, that could work, albleit with some difficulty, and it would not be that precise. Due to the fact that I'd have to use many 8 tooth gears, there would be a lot of backlash, and the gears introduce the potential for breakage.

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I don't think you would get a lot of backlash because its well braced.

You could always brace a worm gear to each side of the turntable ,but would would have to make sure it is well build.

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before you think about a steering system you should think about a more stable axle. your construction is a little bit more than weak

8424470300_02831d6192.jpg

the gears are not properly reinforced, the universal joint must hold the PF-L

the wheels and their crossaxles are only hold by the 12 tooth bevel gears in the diff, and the whole axle is not flexible.

on the picture i have reinforced the connection between turntable and 5to11 liftarm.

the 5to3 liftarms are only secured by one pin and the axle through the torque tube part.

and with 1:2,334 the gear ratio is too fast for a vehicle like this

edit: my version

i have moved the motor to the chassis because so much L motors are too expensive for a real model

8423750097_cc73120377.jpg

ETF HTX-380 Mining Truck von efferman auf Flickr

Edited by efferman

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i will do it, but i will use the ldd because i would need the tires of my unimog. and sorry, this is absolutely not an option :wink: this axle pair i have only built to check the function

Edited by efferman

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i think i have a good working steering system

It seems very symmetric to me, but since the steering lock is not great that probably will not matter. The real thing can just about pivot on the inside middle wheelset, so they use fancy computer control to get every wheel angled properly. I was trying to work out a mechanical solution for this, even approximate, but I gave up at the cam operated gearbox stage. Even disallowing crabbing, the "ackerman" compensation has to be huge on the front wheels because the width is so great compared to the turning circle (it's not quite 1:1).

I wonder whether the plans for the real thing use strain guages to correct the steering angle, rather than trying to estimate suspension movement and pre-steer to compensate (as one wheel of the pair lifts the centre moves sideways, stressing the support pillar). Given the size of the truck it's not out of the question that they use live ground measurement of some sort - I haven't seen it mentioned but it seems obvious to me.

And "too expensive"... from someone using 20 unimog wheels!

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@ too expensive

tires are tires and dont need something else, but every four PF-L you need (in best case) an receiver and a battery box. saberwing 40ks ldd model had 14 PF-L. so there would be need to buy electrics for roundabout 350 euros (batteries and connection problems not included. so i will go a more efficent way and use 2 XL

@ackermann

the difference should be enough to get a proper ackermann geometry at the second axle. the insane is, to find out if it is correct i have to build the whole chassis. damn, this should be an ldd project, but this is the only way to make it work fine.

by the way, the second axle on the left side is made in LDD

8429424146_bacc565d13.jpg

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There is also MATLAB, if one is inclined to that sort of stuff. Or Python for that matter.

Edited by stfn

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