Thirdwigg Posted November 12, 2015 Posted November 12, 2015 Some projects just take a long time to complete. The Audi allroad is finally complete, and since it took so long to come together, I took it apart yesterday. I guess I was a little more motivated by the disassembly, than by the assembly. More information is at thirdwigg.com. A video can be found , but keep your expectations low.Features: All wheel drive Steering by PF Servo Three speed transmission Drive by three PF L motors All wheel independent suspension Roof rack for all your toys Enjoy, and happy building. Quote
Zerobricks Posted November 12, 2015 Posted November 12, 2015 That looks really well done! The wide tyres really make it look sporty! How does the drive work? Can you explain the idea behind it? Quote
grum64 Posted November 12, 2015 Posted November 12, 2015 (edited) A great build & with it being battery powered the first 'honest' Audi built in recent years? Edited November 12, 2015 by grum64 Quote
Thirdwigg Posted November 12, 2015 Author Posted November 12, 2015 (edited) That looks really well done! The wide tyres really make it look sporty! How does the drive work? Can you explain the idea behind it? Basically each motor is a gear, with the differentials reducing the speed when a motor is not operating. When all three motors are running, no subtraction happens through any of the differentials. It's simple, and works pretty well. Edited November 12, 2015 by Thirdwigg Quote
zux Posted November 12, 2015 Posted November 12, 2015 What if you switch the motor to rotate the opposite direction? I assume it will slow down in speed and increase the torque? Quote
2LegoOrNot2Lego... Posted November 13, 2015 Posted November 13, 2015 (edited) Love the logo to start with and the grill in general, that really stands out... That is not all, love the bodywork also and the functionality! Great "gearbox" even though it is a little expensive this way... BTW, checked the video, it sure needs difs in front and rear axle... turns hard... What if you switch the motor to rotate the opposite direction? I assume it will slow down in speed and increase the torque? I doubt this even though it sounds like it would make sense... Probably both motors having running the opposite direction just makes them doing nothing at all... Not sure though Edited November 13, 2015 by 2LegoOrNot2Lego... Quote
Thirdwigg Posted November 13, 2015 Author Posted November 13, 2015 (edited) Yep, the suspension and drive works better with rear wheel drive; differentials would be better in this all wheel drive application. I doubt this even though it sounds like it would make sense... Probably both motors having running the opposite direction just makes them doing nothing at all... Not sure though Correct, if you run two motors in the opposite direction, the car will stay put and not move. Edited November 13, 2015 by Thirdwigg Quote
zux Posted November 13, 2015 Posted November 13, 2015 Oh true-true, the car will stop. Not sure what I was thinking Quote
JamesJT Posted November 13, 2015 Posted November 13, 2015 (edited) So with different gearing from the motors in to the differentials you could make a 3 speed with just 2 motors. One motor backwards to slow down and forwards to speed up. The other motor would just be on or off. 3 motors, all with different gearing would give 27 speeds(?) Somebody check my maths, that sound like way too many I like that they would be seamless changes too. Edited November 13, 2015 by JamesJT Quote
PKW Posted November 13, 2015 Posted November 13, 2015 lot's of time i thought about building subtractor "gearbox" biut the problem is that the torque of one motor weigh on all the other motors, and of motor torque is really lower than the one of the powered one so i think the car slows because other motor turn in the opposite direction and detract speed while they are unpowered, furthermore lego gears absorb loto of power and bevel gear also a bigger amount... so i don't trust in this kind of gearing, do you have a video where you show the different speed of the different "gearing"? anyway, the look of this car is really cool! Quote
Lakop Posted November 13, 2015 Posted November 13, 2015 Great build. On this occasion I would like to see it stripped of the motors and have some internals, seats etc. I would like to see it built without the PF. H PS: Then maybe a sporty version Quote
Thirdwigg Posted November 13, 2015 Author Posted November 13, 2015 (edited) lot's of time i thought about building subtractor "gearbox" biut the problem is that the torque of one motor weigh on all the other motors, and of motor torque is really lower than the one of the powered one so i think the car slows because other motor turn in the opposite direction and detract speed while they are unpowered, furthermore lego gears absorb loto of power and bevel gear also a bigger amount... so i don't trust in this kind of gearing, do you have a video where you show the different speed of the different "gearing"? anyway, the look of this car is really cool! The video link is posted above. Great build. On this occasion I would like to see it stripped of the motors and have some internals, seats etc. I would like to see it built without the PF. H PS: Then maybe a sporty version Thanks. I took it apart already as I was ready to be done with this project. Feel free to take a swing at it, and let me know what you came up with. So with different gearing from the motors in to the differentials you could make a 3 speed with just 2 motors. One motor backwards to slow down and forwards to speed up. The other motor would just be on or off. 3 motors, all with different gearing would give 27 speeds(?) Somebody check my maths, that sound like way too many I like that they would be seamless changes too. It's not quite that complicated. Basically think of it as three motors all spinning in the same direction; one for each gear. When you turn on each motor, it increases the speed applied to the wheels. Think of it this way; take any LEGO vehicle with a fake motor and a differential connected to two wheels. Turn one wheel while holding the other stationary, and note the speed of the fake motor (half the speed of your wheel rotation). Now spin both wheels in the same direction, and the fake motor will spin faster (the same speed as both wheels). The allroad uses this concept twice by having three motors (e.g. wheels) move through two differentials to the drive axle (e.g. fake motor). Edited November 13, 2015 by Thirdwigg Quote
JamesJT Posted November 13, 2015 Posted November 13, 2015 (edited) I get how your system works, I just noticed that you could have 3 speeds with just 2 motors in to 1 differential. Edited November 13, 2015 by JamesJT Quote
Thirdwigg Posted November 13, 2015 Author Posted November 13, 2015 I get how your system works, I just noticed that you could have 3 speeds with just 2 motors in to 1 differential. Correct, but I use three motors rather than two different ratios. Quote
LEGO Train 12 Volts Posted November 14, 2015 Posted November 14, 2015 Nice one! I really line the front! Quote
2LegoOrNot2Lego... Posted November 14, 2015 Posted November 14, 2015 Yep, the suspension and drive works better with rear wheel drive; differentials would be better in this all wheel drive application. Correct, if you run two motors in the opposite direction, the car will stay put and not move. May I ask why you did not implement differentials then? IMHO it would for sure increase the overall performance of this beauty! I already thought so, but was not sure...thanks... 3 motors, all with different gearing would give 27 speeds(?) Somebody check my maths, that sound like way too many I get how your system works, I just noticed that you could have 3 speeds with just 2 motors in to 1 differential. This explains a lot and indeed the different gearing even add one gear to it, nice concept. Agree with PKW though that it is not that efficient, but works well! What about the math, you were able to check it yourself... :laugh: I am curious! Quote
Thirdwigg Posted November 14, 2015 Author Posted November 14, 2015 May I ask why you did not implement differentials then? IMHO it would for sure increase the overall performance of this beauty! I already thought so, but was not sure...thanks... I did not use Differentials due to the space, as independent suspension was my first priority. I think I can make it work with a floating setup like my 8081 RT, but that may be a couple of MOCs from now. Quote
2LegoOrNot2Lego... Posted November 14, 2015 Posted November 14, 2015 I did not use Differentials due to the space, as independent suspension was my first priority. I think I can make it work with a floating setup like my 8081 RT, but that may be a couple of MOCs from now. That makes sense, thanks! Nevertheless, as I already told you I really love this MOC!!! Quote
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