New Prototype Crawler Axle

[Someonenamedjon]

WOW! The axle is really big, are you going to make two and then make a whole crawler?

[Alasdair Ryan]

WOW! The axle is really big, are you going to make two and then make a whole crawler?

What is the point of making a crawler with one axle?

Max I think your construction of the chassis is quite weak and messy,I would try to make a better chassis if I was you.

Edited April 13, 2013 by Alasdair Ryan

[Someonenamedjon]

What is the point of making a crawler with one axle?

Max I think your construction of the chassis is quite weak and messy,I would try to make a better chassis if I was you.

i meant making two and attaching them together to make a crawler, so he makes two of the axles.

[Alasdair Ryan]

Ah but what you said and what you meant is different.

[z3_2drive]

What is the point of making a crawler with one axle?

Max I think your construction of the chassis is quite weak and messy,I would try to make a better chassis if I was you.

well, I did build it all in a couple hours and there was a lot of half stud offsets to deal with, but actually, it's much stronger than it looks and of course i'll make changes in the future but I'm leaving the main structure as it is because it's strong and it works. And Tim, that idea looks very interesting and if I find this does not have enough torque in the end i'll switch to it-BUT it makes the wheelbase 4 studs longer and I dont really want that... Edited April 13, 2013 by z3_2drive

[AndyCW]

This transmission/output selector will work fine in my last crawler chassis. I used a 24t, worm, and PF Med to shift gears. I ended up twisting a 4l axle w/stopper, but it worker fine.

9:1 axle plus transmission meant that at 7.4 Vdc I had some trouble with really large obstacles in low gear. Your higher voltage should mean that you will have no problems. Higher speeds almost require return to center steering. It was hard to drive well in high gear.

Why do you have the extra link on the top of the axle? You can eliminate it if you increase the level of triangulation on your four link. This looks promising.

v/r

Andy

Edited April 13, 2013 by AndyCW

[z3_2drive]

Why do you have the extra link on the top of the axle? You can eliminate it if you increase the level of triangulation on your four link. This looks promising.

v/r

Andy

haha I know, but the way I situated the links may need some work, I was trying to finish quickly, and I also was thinking about your KOTH crawler while building this

[AndyCW]

My latest iteration has a four speed transmission. I am working out the kinks right now. I may create myself a custom 9.6 volt battery pack to follow your trend.

[z3_2drive]

My latest iteration has a four speed transmission. I am working out the kinks right now. I may create myself a custom 9.6 volt battery pack to follow your trend.

sounds promising-will it be more of a trial truck than a crawler?

hey Andy, I fixed the triangulation! was very easy and actually offered another strengthening point in the middle Pic-

[AndyCW]

It is a cross between this and my KOH truck.

This looks better with the elimination of the extra link.

I like building in this method because it allows me to isolate different modules and work independantly. You can improve the axles independantly of the chassis and vice versa as well as working on the body separtely from everything else Edited April 14, 2013 by AndyCW

[z3_2drive]

interesting, I always enjoy watching videos of those rock buggies, especially Tim Cameron. I wonder if buggy motors could deliver enough torque without too much gear reduction that makes it soo slow... but I' sure it'll turn out great, good luck!

[Doc_Brown]

WOW, I'm totally loving this! Can't wait to see it in action! So many cool ideas, my brain is buzzing.

Those wheels are awesome too! Wish I had RC motors, they look so powerful.

[AndyCW]

Bricklink is your friend. After all, it is only money. You can't take it with you. Have you ever seen a moving trailer towed behind a hearse?

Somebody posted about how to "overvolt" the buggy motors to 18 vdc. This would provide stupid power in a crawler, but longevity of the motor will definitely be downgraded. It all depends on how far each one of us is willing to push it.

v/r

Andrew

[AKM_76]

Love the crawlers, never made them myself yet. I'm not clearly understand something. Is there some explanation how they mechanically behave? For a single wheels axis there is usually 4 links and 2 shock absorbers, i.e. 6 points of contact with a body. For 9398 4x4 Crawler there is 5 points of contact including that 'round parts'. Why 4 links but not a pair of them? Also I saw construction with 4 links without shocks absorbers at all, I just don't understand how the body does not fall on the ground:

Edited April 14, 2013 by AKM_76

[legomuppet9]

Also I saw construction with 4 links without shocks absorbers at all, I just don't understand how the body does not fall on the ground:

On the front axle at least, it's because the body is resting on the axle

[z3_2drive]

Love the crawlers, never made them myself yet. I'm not clearly understand something. Is there some explanation how they mechanically behave? For a single wheels axis there is usually 4 links and 2 shock absorbers, i.e. 6 points of contact with a body. For 9398 4x4 Crawler there is 5 points of contact including that 'round parts'. Why 4 links but not a pair of them? Also I saw construction with 4 links without shocks absorbers at all, I just don't understand how the body does not fall on the ground:

on a 4 link setup-well-on any suspension-all forces acting on the axle have to be equal in order to keep it in place-normally called 'triangulated 4-link' but this is only to keep the axle from moving side-to-side, which is a bad thing for a crawler. Here is a real-life example:

And the reson for having two pairs is if there were only one, the axle would become extremely unstable and rotating up and down...it would look something like this

-the second pair equals out the forces keeping the whole axle stable-and that no-shock absorber crawler is stupid IMO, it can easily roll over and driveshafts can pop out if his geometry is not perfect. It can get complicated with lots of terms and hard to explain through text, maybe andy can give a bit more insight.

[AKM_76]

Thank you so very much, great explanation, seems much clearer now.

Do I understand right that the shock absorber both ends connection points must be able to move just in one (vertical) dimension? Or two dimensions required (vertical)?

And why it is important for the links to be semi- triangular and not rectangular?

Edited April 14, 2013 by AKM_76

[z3_2drive]

Thank you so very much, great explanation, seems much clearer now.

Do I understand right that the shock absorber both ends connection points must be able to rotate it two vertical dimensions and the third one (dimension), horizontal, should be solid?

And why it is important for the links to be semi- triangular and not rectangular?

because when they are rectangular they are parallel-so they are not acting against eachother, which allows the bad side to side movement. And yes but shock absorbers can be placed many different ways to offer different degrees of articulation, check out this topic of mine to see a high articulation setup: http://www.eurobricks.com/forum/index.php?showtopic=72695&hl=

[AKM_76]

I understood now, thank you.

[AKM_76]

Checked your example, you have two degrees of freedom on the lower ends and one on the upper ones? What for is the link on the upper ends of the shock absorbers? Is it to limit the rotating ability of the whole axle?

Edited April 14, 2013 by AKM_76

[z3_2drive]

Checked your example, you have two degrees of freedom on the lower ends and one on the upper ones? What for is the link on the upper ends of the shock absorbers? Is it to limit the rotating ability of the whole axle?

the link on the top of the shocks is just to keep the shocks from coming off the chassis, while letting them move independently at the same time In fact, I decided to use that for the current crawler-here's a photo of the shock setup plus some extra bracing on the axle:

Really like these tires, but they could use some larger treads/knobs whatever you want to call them

Edited April 14, 2013 by z3_2drive

[AKM_76]

Just great. Thank you so very much.

[camaudio]

Really like those tires also. Cant wait to get a set.

[AndyCW]

You may run into issues with your links so far out of plane with the horizontal. When encountering an obstacle, the front axle will try to tuck under the vehicle instead articulating. These forces could cause the links to easily pop off of the towballs or the towballs to pop out of the lift arms. It also causes the front axle to shift forward when compressing. This measn the suspension cycle will be going counter to the obstacle.

[1nxtmonster]

As of the two-speed gearbox, i have one in my 2-speed buggy:

Edited April 27, 2013 by 1nxtmonster