New style of crawling begins

[z3_2drive]

I am showcasing my all new CrAwLeR with four link suspension, lightweight chassis and most importantly, new axles where the 9398's servo motor directly steers with no need for those pesky racks which take up space. I take this as the first model using the servo motor on the axle, but excuse me if someone beat me to it. Theres lots of room to improve because I built this in only a day, but this provides a simple platform for people to change. No room for two L-Motors so I used xl mounted vertically for the least amount of parts and weight. It's AMAZING! Only problem was the fact it's so light that these stupid lego tires(no offense, they're ok for models but not crawling) have little grip. In time I will buy rc tires similar in size to unimog tires to keep wieght down but same scale, and more grip Here's pics:

[Zerobricks]

Nice axles, they remind me of my raptor, but updated with the new portal hubs. Doesnt the 20 tooth half bewel gear next to Xl motor slip?

Try to move the battery box lower. Other than that great!

[z3_2drive]

Nice axles, they remind me of my raptor, but updated with the new portal hubs. Doesnt the 20 tooth half bewel gear next to Xl motor slip?

Try to move the battery box lower. Other than that great!

no the bley gear with pin hole opposite to the tan one with axle hole balance eachother out so no slippage, and yes I'll try to place battery box elsewhere. Axles where inspired by your raptor, yes, but steering of course and top link mounts are different. And axles have much more flex than the Raptor. Glad you like it!

Edited August 3, 2012 by z3_2drive

[skppo]

Lego rock crawlers are coming very close to RC crawlers. Axle mounted servos are common in those.

Only the wheels are lacking but atleast lego offers rims in useful sizes for third party tires.

Nice job on this chassis. It will be great to see these sort of "supercrawlers" developed even further!

[z3_2drive]

Lego rock crawlers are coming very close to RC crawlers. Axle mounted servos are common in those.

Only the wheels are lacking but atleast lego offers rims in useful sizes for third party tires.

Nice job on this chassis. It will be great to see these sort of "supercrawlers" developed even further!

Yes, the only thing separating this from rc performance is a superfast motor with good torque-like buggy motor but with more torque. But I doubt plastic parts would handle it, so thats the limit, but then thats the fun, pushing the limits. It's not metal rc, it is just our wonderful Lego.

[Hopey]

Looks nice.

I can't quite see it clearly, but it looks as though you've mounted the shock absorbers with only one degree of freedom, by simply attaching them with a pin, rather than the two degrees of freedom that the 8110 and 9398 achieve by attaching them with those pins with the hole in the middle.

Doesn't this twist them and put a lot of strain on them when one wheel is lifter higher than the other?

[timslegos]

I would love to see a video of the crawling action. I have been trying to build a crawler for some time now and I can never manage to get the suspension correct, nice job.

tim

[DLuders]

@ z3_2drive: I like the simplified steering setup, and the lightweight design.

If you want to keep the same-scale tires as the Umimog tires you have now, I recommend the "Rock Creepers" tires ( http://store.rc4wd.com/Rock-Creepers-19-Scale-Tires_p_222.html ), which have these dimensions:

Outer Diameter: 3.8" (95mm)

Width: 1.45" (37mm)

Inner Diameter: 1.9" (48mm) .

I own some of these, and have held them side-by-side with the Unimog tires. The Rock Creepers are REAL CLOSE to the Lego Unimog's 92912 tire's dimensions (94.3 x 38R), but with the soft rubber compound and big lugs, it will perform better in rock crawling duties.

Edited August 3, 2012 by DLuders

[z3_2drive]

Looks nice.

I can't quite see it clearly, but it looks as though you've mounted the shock absorbers with only one degree of freedom, by simply attaching them with a pin, rather than the two degrees of freedom that the 8110 and 9398 achieve by attaching them with those pins with the hole in the middle.

Doesn't this twist them and put a lot of strain on them when one wheel is lifter higher than the other?

LOL, just noticed that it looks like that, my bad! Actually it's attached to this piece which can move freely on the axle. It actually has more flex than 8110 or 9398 ever will . For example:

[Lipko]

Looks nice.

I can't quite see it clearly, but it looks as though you've mounted the shock absorbers with only one degree of freedom, by simply attaching them with a pin, rather than the two degrees of freedom that the 8110 and 9398 achieve by attaching them with those pins with the hole in the middle.

Doesn't this twist them and put a lot of strain on them when one wheel is lifter higher than the other?

I am wondering this too. And another thing: how do you define the lateral position of the axles?

Oh I see. There is still some unusual lateral forces on the shock absorbers though, but that's just a minor thing.

Edited August 3, 2012 by Lipko

[z3_2drive]

I would love to see a video of the crawling action. I have been trying to build a crawler for some time now and I can never manage to get the suspension correct, nice job.

tim

Sorry, can't make video, but here's a tip for four link setup, It's all about GEOMETRY. You have to triangulate the links. To simplify this phrase, lets say two links are set next to eachother on a table. they are parallel to eachother at a distance of 5 studs. first, move one end of both links 2 studs further apart. so at one end the links are 5 studs apart and the other ends are 7 studs apart. Now to equalize the forces to keep the axle the links are connected to from moving side to side is to add two links on top of the previous two at opposite angles. this is too confusing. Here's an example:

[z3_2drive]

@Dluders thank you, will probably get those in coming months. Great to see so much feedback! It's like brainfood for more ideas Be sure to visit my brickshelf! link is below.

Edited August 3, 2012 by z3_2drive

[Lipko]

Sorry, can't make video, but here's a tip for four link setup, It's all about GEOMETRY. You have to triangulate the links. To simplify this phrase, lets say two links are set next to eachother on a table. they are parallel to eachother at a distance of 5 studs. first, move one end of both links 2 studs further apart. so at one end the links are 5 studs apart and the other ends are 7 studs apart. Now to equalize the forces to keep the axle the links are connected to from moving side to side is to add two links on top of the previous two at opposite angles. this is too confusing. Here's an example:

Hmm. That makes sense. The lower "layer" wants to make the axle rotate in the opposite direction than the upper "layer" if you try to push the axle in a lateral direction.

But the image shows slightly bigger angle than your implementation. Does the angle only affect the backlash sensitivity of the suspension (backlash of the ball joints of the links)?

Edited August 3, 2012 by Lipko

[Aussie BJ]

Now that's some serious articulation well done!

Brendan

[Kisvakond]

Hey z3_2drive!

I really love this design, nice work indeed!

- I see you just mount your PF Servo like the way on most RC Crawlers / AWD Cars was mounted

>> Q#1: Is it stiff/holds itself enough?

- I love the longer 4-link suspension supports

>> really nice wheel travel achieved! Congrat!

Sooner or later could you make for us some short in-action vid, please..

Edited August 3, 2012 by Kisvakond

[z3_2drive]

Hmm. That makes sense. The lower "layer" wants to make the axle rotate in the opposite direction than the upper "layer" if you try to push the axle in a lateral direction.

But the image shows slightly bigger angle than your implementation. Does the angle only affect the backlash sensitivity of the suspension (backlash of the ball joints of the links)?

I'm not sure but I think the greater the angle the less side to side movement , because I can still move the axle slightly side to side , but it's too little to make a difference in a lego model. Another thing I wanted to point out is that the point where the ball joint is attached has to be in line with the middle of the U-joints to prevent the axle from the driveshaft to pop out. the way I built it one side isn't in line so If the chassis was higher in the middle the axles would pop out. But I have it limited to the maximum clearance befrore that can happen, you can research it if you want further understanding, because this stuff just comes to me naturally :)

Hey z3_2drive!

I really love this design, nice work indeed!

- I see you just mount your PF Servo like the way on most RC Crawlers / AWD Cars was mounted

>> Q#1: Is it stiff/holds itself enough?

- I love the longer 4-link suspension supports

>> really nice wheel travel achieved! Congrat!

Sooner or later could you make for us some short in-action vid, please..

A#1: It's stiff enough, yes. This piece with the ball joint on the servo sometimes slips out after a long time of constant steering but I'ts ok. It needs some improvement... for equal steering I'd need a 9L link with the servo a bit to the left or right from the middle of the axle. But as it is it turns(when on a flat surface) a bit less in this direction:

Regarding a video...sorry but no promises, I'd like to though because this performs very well, maybe could do windows media player video, but the main reason...I'm not sure if I have a proper camera. Maybe could make youtube account but need permission, as I am (sorry please dont ban me, I behave!) a bit underage.

Edited August 4, 2012 by z3_2drive

[z3_2drive]

Doesnt the 20 tooth half bewel gear next to Xl motor slip?

For the first time It did, but this is because I went crazy and tried to climb impossible negative incline But it handles everything great and front climbs up straight 90 degree angle with no problems

[timslegos]

great and front climbs up straight 90 degree angle with no

I dont think that it is possible to climb a 90 slope . Any video is better than no video!

tim

[LEGO Train 12 Volts]

Very cool realization!

I like the neat design!

[z3_2drive]

I dont think that it is possible to climb a 90 slope . Any video is better than no video!

tim

I mean the front axle can drive up, of course when the back axle gets there it flips over

Edited August 4, 2012 by z3_2drive

[allanp]

Having the servo motor in the axle makes much more sence than having the drive motor in the axle, kinda like an electric power steered axle (but without the link to a working steering wheel ).

[daniele]

Waiting my 9398 I tried to do a servo :D

(I think it has not enought power for a big truck )

[z3_2drive]

Yeah the servo motor's pretty powerful, I usually used the m motor with hockey spring before this came out but It broke both pieces Now just need to buy a second set of L-motors, servo and v2 receiver so I can have two rc models at once instead of switching electronics from MOC to MOC.