Hrafn

Since I'm working on a white car myself, I'm quite pleased - though now I wish I'd waited a bit to buy the panels from BL until the prices dropped some. Maybe we'll see some of the 'very small' panels in white in one of the 2H2014 sets. Here's hoping...

Or if you have any of the old 9V extension cords (and the inventory for 8479 shows it contains several), those can connect to micro motors and 2838 motors.

I agree. Whatever TLG's reason was for putting the servo in this set, doing so without also including the train remote strikes me as a mistake. Alternately, they could have used a PF-M and either linear actuators or a series of gears to do the steering; that would have worked fine. This is one of those compromises that just doesn't work, IMO.

Really? From this picture it appears to be one part. What am I missing?

Thanks for doing that! Lacking a tachometer myself I couldn't do the test here. Do you remember roughly what the percentage losses were when the parts weren't put together well? Was it a question of misalignment, rubbing, flexibility in the support structure, or what?

Outstanding creation! The video is also very well put together.

If you're still working on this, is there a way to use or or something similar instead of on the rear suspension, to reduce its thickness to 2 studs? The bike looks great so far and I really hope you get to finish it.

I'd also add this: high quality and durability are worth paying for. Most of my childhood toys quickly fell apart or were discarded or sold because they had lost their limited play value. But I've saved all of my childhood Lego for my kids to play with - and almost all of it is in excellent condition. That's a useful lesson outside of Lego - when I need, say, a winter coat, it costs less in the long run to buy a good one initially instead of buying something cheaper that won't last.

5 is nice, but unfortunately according to Bricklink that part has never been made in yellow.

Your early-morning English is clearer than my pre-coffee English, and it's my native language, so no apologies necessary! I thought it might be too complicated to really measure, but it's good to hear that from someone who's been building with Technic for a while. Your explanation of the axial and tangential forces makes sense, thank you (or köszönöm, as my mother would say).

They should be useful for building complex angles into models, but unfortunately are unlikely to be useful for Technic suspensions - the joint has a lot of friction in it. They also appear in the Chima Legend Beasts, especially 70123 and 70127.

Is there any chance it got wet?

Oops! Right you are. I agree about this being a somewhat complex design for multiple axles, but it would work. Note the 16t clutch gear above the differential that engages with it. My guess is that another gear, connected to the motor, drives this clutch gear and thus the differential. The same setup could be repeated for an arbitrary number of axles, though it requires a lot of space (especially vertically). EDIT: in terms of gearing, it also works to do this: power the axle going into the 24t side of a 4L differential connect the other axle to a 12t single bevel, which drives a 12t double bevel (and one wheel) connect the 16t side of the diff to a 24t crown gear (which drives the other wheel) However, I couldn't figure out a good way to connect the structure for the half-axles.

That's a good point. Intuitively I would think the same, but it would be nice to have some experimental data to check intuition against. Zblj, could you expand on this? I would also expect larger gears to be more efficient than smaller ones because of reduced backlash. I'm also curious to know if power losses depend on whether the gears being meshed are spur to spur, bevel to bevel, or spur to bevel. The bevel gears seem to be made of a softer material. I think the profile of their teeth is essentially the same as those of the spur gears, though.

Has anyone attempted to measure the power loss from gearing motors up or down? What I'd really like to find is something like Philo's excellent work on motor specifications, batteries, tire traction, and so forth. Ideally it would compare all common pairs of gears (8/8, 16/16, 12/20, 8/24, 8/40, etc.) for at least a couple of motors.

Take a look at allanp's other photos (there's a link at the bottom of post #10), especially this one: It looks like he's running two driveshafts off the differential. One, visible from the bottom, comes from the axle on the wheel side of the differential, and it drives the tan bevel gears and one wheel. The other comes off the other side of the differential, going from the black 12t gear to the 20t gear above it, along that axle, and then (as far as I can tell) to another 20t/12t pairing on the far side of the wheels to drive the black bevel gears and thus the other wheel.

I'm holding out for this

Apparently so.

Ditto to all of the above. My undergraduate education is in mechanical engineering but I had zero interest in cars, so it's a bit embarrassing how little I knew about how they work.

Off topic here, but this is apparently a real problem with full-size electric cars. I know someone with a Nissan Leaf, and winter temperatures (even in California!) noticeably reduce the car's range. Charging and discharging batteries involves chemical reactions, and all chemical reactions happen more slowly in lower ambient temperatures. If Nissan can't insulate their batteries enough to prevent this problem, I doubt it's possible in a Lego model.

The short explanation is that a differential (in the Lego model this is a dark gray tubular part that has 3 small gears in it, located between the rear wheels) allows the wheels to rotate at different speeds. If the vehicle is stationary, then yes, one wheel will go forward and the other backward. If the vehicle is moving forward, then both wheels roll forward - but they may do so at different speeds. The reason for this is that when the car turns, one side of the car moves in a tighter curve than the other, so the wheels on that side move more slowly. For a longer but very clear explanation, watch .

It's hard to tell from the small photo exactly how the steering on the real thing works, but one approach to an apparently similar tractor is here. Search the forums (and MocPages and flickr and Brickshelf) for "articulated hauler" and you'll find similar implementations. The linear actuators are probably a better solution than pneumatics, because they move slowly and can be stopped at any intermediate position; pneumatic cylinders are much harder to control precisely.

Thanks! Since you didn't mention turntables in your title, I didn't put the two together - I thought you'd somehow found a way to make driving rings for gearboxes that could select between three different gears, and I didn't see how that was possible with those parts. Looks interesting, good luck!

I suspect that some version of Zblj's "Twister" tri-star setup is going to work best. It's simple and looks pretty robust, and the arms are spaced at exactly 120 degrees.

Could you explain how this works? I'm not getting it just from looking at the pictures. Thanks!