Author Topic: Steering Idea: A "Fluid Draglink" (Read 6722 times)

RynothealbinO · « **on:** Nov 21, 2006, 08:41:56 AM »

I have been playing with the idea of putting crossover steering on my 4Runner but that still leaves me with a couple of problems: 1st, cost, 2nd, I would still have bumpsteer. Even if I built a 4-link with a panhard bar triangulated with the drag link I would now have the axle travel in an arc and that would cause a ceartain amount of bumpsteer. So to solve these problems I was thinking I would eliminate the drag link all together

. I was planning on mounting a small hydraulic cylinder on the framerail right behind the steering box. One end would attach to the frame and the other to the steering arm so that when the crlinder was at the center of its stroke the steering box would also be cendered. I would mount another cylinder whith one end mounted on the axle and the other to the tie rod so that when the steering was centered the cylinder would again be at the center of its stroke. Then you just run a hydraulic line between the two cylinders. That way the suspension has NO effect on the steering and if you made it wourself it could be done rather inexpensively. I know that some might be scared for the lack of a solid link but you trust your brakes to lines that are much thinner and see higher pressures, so why not do it? And if you bled the system properly there really would not be a whole lot more slop than if you just ran a solid drag link. So what do you guys think?

crawlerdan · « **Reply #1 on:** Nov 21, 2006, 09:05:15 AM »

allright captain engineer!!! that sounds cool, i understand what your saying...a drawing might help others understand...

i think you should be marlins crash test dummy and fab it up so we all can see

graet idea man

crawlerdan · « **Reply #2 on:** Nov 21, 2006, 09:07:21 AM »

oh ya..on a side note, i have a 4runner with a solid axle and crossover and have absolutly no bump steer that is noticable while operating the truck...im using marlins kit, a relocated toyota box, and the axle is moved foreward 4.5 inches, just my

toynorcal · « **Reply #3 on:** Nov 21, 2006, 10:58:35 AM »

Sounds to me like a single hydro-ram assist would be more reasonable for what you will accomplish. Most crawler guys will lean towards beefy steering set ups, but this could be reasonably strong and lower profile. You may want to consider mounting the upper cylinder tucked up under the radiator area to reduce the lenght of hydraulic line you will need and to keep things up away from snags.

snowplow · « **Reply #4 on:** Nov 21, 2006, 12:30:08 PM »

I love your Idea because I have bumpsteer too (not much but it is supposed to be non-existant)
Definitely post to let us know if it works. I dont see why it wouldnt... snowplow

CTENG in KS · « **Reply #5 on:** Nov 21, 2006, 12:35:23 PM »

This was brought up on Pirate the other day...was that you too?

Here are your issues...
...the slave cylinder needs to be no larger than the master (at the box end).
You can't use a little ram at the box to move a big ram at the axle because of the simple fact that, while the force may be transfered 1:1, you will not have the displacement at the axle necessary to fully turn the wheels.
You will therefore have to use a big ram at the box and at the axle...
You will have lots of fun mounting that ram somewhere at the frame and you will incur the cost of two large hydro rams...you are pretty much nearing the cost of just going full hydro from the begining except you now have a pump, steering cylinder, and TWO rams.

RRMike · « **Reply #6 on:** Nov 21, 2006, 03:42:13 PM »

Quote from: RynothealbinO on Nov 21, 2006, 08:41:56 AM

Even if I built a 4-link with a panhard bar triangulated with the drag link I would now have the axle travel in an arc and that would cause a ceartain amount of bumpsteer.

A panhard bar with crossover and the panhard the same length and mounted at the same angle will completely eliminate bumpsteer. It causes the axle to travel through a side to side arc specifically to keep the distance between the steering box and the pass knuckle constant throughout the suspension cycle thus completely eliminating bump steer.

That being said I like your idea but I wouldn't want to try to make it work.

RynothealbinO · « **Reply #7 on:** Nov 22, 2006, 07:56:11 AM »

To clarify a few things, first the purpous of this is not for hard core rock crawling (I live in Minnesota) but a way that will allow me to do whatever I want with the suspension without having to worry about the steering. I eventually want to do a 4-link just because I can and don't want to have to design my suspension around steering components. Secondly, I do realize that if you set upm the drag link and panhard bar with the same geometry you will not have any bumpsteer in theory. But think about it, when the suspension moves up and down the axle will now move side to side slightly forcing the front of the truck to move side to side throughout the travel of the suspension. And that will cause the rear axle to turn unless its 4-link is set up the same as the front 4-link. The second thing is that this would not be expensive or complicated. It would use 2 smallish double acting cylinders and 2 hydraulic hoses, thats it. There would no extra pumps or anything to worry about. The only problem that I see is that it will be harder to steer simply because of the resistance from friction in the cylinders and in the lines. The whole system will act like a steering dampener but I don't think thaere will be enough resistance to make steering a chore. it would still be way better than manual steering. Thirdly, you could use the same size cylinder on the axle and the steering box. You just have to set it up so that the relationship between the motion of the drag link and the tie rod maintains the same ratio. I am geussing that the ration would not be to far away from 1:1 so just do the math and figure it out.

snowplow · « **Reply #8 on:** Nov 22, 2006, 09:32:32 AM »

I like your style!

RynothealbinO · « **Reply #9 on:** Nov 22, 2006, 09:50:17 AM »

I was thinking that I would use a cylinder similar to the one on this link: http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_413202_413202 Oh, that wasn't me on pirate so I have so I have no clue what you are talking about. I plan on using two of the same size cylinders. The ones on the link only costs $60 apeace so it won't be very expensive.

milla85 · « **Reply #10 on:** Nov 22, 2006, 10:19:37 AM »

I think the thought of full hydro steering is spooky due to the fact you truly have no phsycial link to the steering! I know that my brother was driving his boss mans truck on the highway and it has full hydro steering and the duramax decide... 65 on the freeway and no steering!!! Not a pretty sight. Thats my 2

. But hay do what you want, maby you will start like a "way cool" trend... dood

- Nick

RynothealbinO · « **Reply #11 on:** Nov 22, 2006, 11:14:45 AM »

Actually, it would not act like full hydro al all, it would be just lke regular steering with a little more resistance. On full hydro steering the hydraulic cylinder is not able to push back on the steering wheel, but in this system the tires are able to push on the steering wheel making it act as if you had traditional steering. But yes you could still lose control if BOTH hoses blew but I don't know how you would do that since they should be able to handle the output of a pump at MUCH higher pressures. Oh, I will try to post some sketches later dotay since I am currently at school.

BigMike · « **Reply #12 on:** Nov 22, 2006, 12:13:03 PM »

I had to read your post a couple of times to understand what you are talking about.

I think this correction will make it MUCH easier for others to understand if they can't picture it yet:

You wrote:

Quote from: RynothealbinO on Nov 21, 2006, 08:41:56 AM

I was planning on mounting a small hydraulic cylinder on the framerail right behind the steering box. One end would attach to the frame and the other to the steering arm so that when the crlinder was at the center of its stroke the steering box would also be cendered.

But I think it should read:

Quote

I was planning on mounting a small hydraulic cylinder on the framerail right behind the steering box. One end would attach to the frame and the other to the pitman arm so that when the crlinder was at the center of its stroke the steering box would also be cendered.

I kept trying to visualize a hydraulic ram positioned vertically from the frame down to the steering arm on the knuckle and I was thinking, "what, how can that stop bump steer, that could stop articulation" hahahaha

I think the problem with the hoses would be if something on the road camp up and hit your lines or something. Of course you will use hose of extra length and route them neatly and perhaps even protect them with some shielding if necessary, so that problem can always be avoided.

It sounds like a great idea, and it would solve a HUGE problem that I am having right now with my draglink, but it seems that the resistance would be very very large, no? I have zero experience with hydro rams, I don't even know what it feels like to move one in and out when its bone dry. But when I think of my 37x13.5 tires aired down to 3 psi in the rocks, that is a lot of force required to turn my tires, and if those rams have a lot of resistance, it would make it really hard on the steering box.

I am VERY interested to see how this goes. If it works out successfully for you, then I would HIGHLY consider doing it to my rig.

Keep us updated

BigMike · « **Reply #13 on:** Nov 22, 2006, 12:36:32 PM »

I just talked to TURBO about this, and we were discussing just what exactly this system will eliminate.

It will eliminate BRAKE steer, or Suspension-cycling steer, but now I think we need to define what bump steer is.

If bump steer is when you drive over a speedbump at a perpendicular angle, which then causes your steering wheel to react, then that is the same as Brake steer when you brake hard and your truck dives, your suspension is compressing which causes your draglink to move towards the direction of least resistance, which happens to be the pitman arm.

But what about when you drive your truck in Crawl at a brickwall at a 45degree angle. As the front tire approaches the wall, it will immediately try to climb it and the steering wheel will likely be forced into the wall, since as the tire climbs the wall, the wall would pull the tire into the wall. Depending on the angle, wreathe the tire is pulled into the wall or turned away does not matter to prove my point that the tire will still be forced to turn.

Now is that bump steer? Because your double ram setup will not eliminate that kind of bumpsteer, but instead it would just act as if you had like 10 steering stabilizers installed...

So I think your idea is Great to eliminate Brake Steer, but it will not stop the steering wheel from reacting to say if you went over some railroad tracks at a slight angle.

But that of course is related to when you come out of corners, the steering will naturally recenter itself with little input from the driver. That of course is great to have. But going over a speedbump at any angle other than zero will cause some bump steer.

Again, I really like this idea because I am having trouble with my draglink to oil pan clearance, and eliminating the draglink would be extra sweet in my case. Plus I dislike brake steer, so I am all for it

FIREBALL · « **Reply #14 on:** Nov 22, 2006, 01:06:28 PM »

I saw this setup on a buggy about 8 or 9 years ago. Seemed to work very well. If you drive this rig on the street you may want to check your local laws. It may be illegal to have no physical link. In Cali you can have hydro assist but not full hydraulic because full hyd has no drag link.
Also you would only have to have 1 of those hoses fail to have a major ouch happen.
Again, I like this idea, but your argument about bump steer doesn't really stand up. If your geometery is such that you don't have bump steer driving down the road your golden. You aren't going to notice the effects of the spring arc vs the steering when your in low range going through the twisties. Unless you're jumping it (not a great idea in a yota) you won't feel any bump steer.

The buggy setup I saw actually had the steering box behind the dash with the ram. This way he didn't have to run steering linkage past the motor.
This setup would probably work better with a chevy box and pump since the yota ones are a bit under powered.

RynothealbinO · « **Reply #15 on:** Nov 23, 2006, 08:30:20 AM »

Yeah I guess you guys are right about the bump steer versus brake steer thing. Even if you look in major off-road magazines you will find that what should be called "Brake Steer" or "Suspension-Cycling Steer" is always referred to as "Brake Steer", in fact I have never heard of either of these terms so maybe you guys should write in to the major magazines and school some noobs. But yes, this would not eliminate bump steer, but neither could any other type of non full hydro steering. I also know that if you properly set up a 4-link there will not be any Suspension-Cycling Steer at the front axle but because of it traveling in an arc side to side you could have your front axle move up to a few inches left or right throughout the cycle of the suspension. Even though that would require massive amounts of travel to happen there would still be some left to right travel even at normal use. It's not that you would notice it, but that you could notice it. You would not notice a pull at the steering wheel but the whole vehicle would rotate left or right slightly. So back to the real subject, when I said steering arm I meant pitman arm as "Big Mike" has pointed out, so thank you for that. Hopefully the attached sketch will help eliminate any further confusion. As far as line breakage you would have to lose both lines to lose total control. Even though on a double-acting cylinder each chamber is designed to push only one way you could still use it to pull on the fluid well enough to get yourself down to a stop in the event of one line breaking. I believe that the lines and the cylinders in the drawing were accidentally oriented correctly (I really was't thinking about which way they should be mounted but in hindsight I did draw it right...I think).

Hyena · « **Reply #16 on:** Nov 23, 2006, 09:49:36 AM »

I don't get it. that is just like full hydrolic steering but with only one ram. this is also illegal for the road since there is no mechanical linkage for the steering.

79coyotefrg · « **Reply #17 on:** Nov 23, 2006, 10:39:35 AM »

Quote from: Hyena on Nov 23, 2006, 09:49:36 AM

I don't get it. that is just like full hydrolic steering but with only one ram. this is also illegal for the road since there is no mechanical linkage for the steering.

many heavy offroad trucks ie, LARGE cement mixers use this exact set up, the only diff is they do have a tierod but the drag link is actually a hydraulic cylinder

this guys idea is even better because the system when bled of air would be sealed

and would use the stock push pull steering boxes everybody tosses aside now

BigMike · « **Reply #18 on:** Nov 23, 2006, 12:18:53 PM »

Yeah it would be harder to mount the ram with an IFS box, like many of us have. Now the push-pull box becomes valuable

I never thought I would say that

Hyena: The cool thing is that your steering system would remain intact or in the best case, stock and unmodified. The double ram idea has no additional pumps, does not add any load to the stock steering pump (per say), and it is a completely sealed system with low pressure. So the chances of leaks or malfunctions are greatly minimized.

A Hydro assist or full hydro system will actually assist or control steering of course, where as this system is not intended as an assist system. It hopefully will drive and steer just like a regular Crossover system. Running this system with 66" tires aired down to 1 psi will definitely merit the addition of an assist system (real hydro).

This is just to get rid of brake steer, the tie rod, don't have to worry about the pitman arm to leaf spring clearance any more, don't need a steering stabilizer, etc.

IronClad · « **Reply #19 on:** Nov 23, 2006, 12:29:23 PM »

all i could see would be that this setup would be slow. and not safe for the road.

CTENG in KS · « **Reply #20 on:** Nov 23, 2006, 05:53:54 PM »

I am still with IC on this...is is NOT going to be a good system.

DTB · « **Reply #21 on:** Nov 23, 2006, 06:01:41 PM »

Quote from: CTENG in KS on Nov 23, 2006, 05:53:54 PM

I am still with IC on this...is is NOT going to be a good system.

x3

Hyena · « **Reply #22 on:** Nov 23, 2006, 06:59:18 PM »

plus there is still the weak cast steering box mount plate on there.

IronClad · « **Reply #23 on:** Nov 23, 2006, 07:26:06 PM »

yup. lets say you get your tires in a bind. with no steering link there whats gonna move the tires? the toyota pump doesnt make a whole lot of pressure. so that doesnt mean its gonna push that ram. its going to try and compress and then it will break whatever on the steering box. The only reason a full hydro setup works is because a pump is actually flowing fluid into that ram. You're just trying to push it. If that draglink was still there you still have somthing pushing on the tire so your strength plus the PS is doing its job.

But hey try it. I think its a pretty redundent setup. the point of a ram assist or full hydro is to have more power to turn the tires. And if you build a suspension right and put the steering box in the right spot there wont be any problems. If you want to half ass it and ghetto it because you dont want to build it right thats yer deal..

but hey like i said.. try it and if we dont hear from you ever again i'll know it didnt work out right LOL

fullthrottle · « **Reply #24 on:** Nov 23, 2006, 08:16:01 PM »

why not do this it would be cheeper

http://board.marlincrawler.com/index.php?topic=10579.0

http://board.marlincrawler.com/index.php?topic=4699.0

RynothealbinO · « **Reply #25 on:** Nov 23, 2006, 09:54:16 PM »

I am not trying to replace full hydraulic assist or even increase the amount of force that the steering can supply. This system would work just like a traditional steering set up minus some extra resistance from the cylinders. The intent of this is just to think outside the box and try something that hasn't been done, not to be a half done cheap replacement for crossover steering. The forces on the steering box would all be EXACTLY the same as the forces on a traditional steering set up. The pitman arm traditionally pushes on the drag link which then pushes on the steering arm, this would still work the same. The only difference is that instead of the pitman arm pushing on a steel bar (the draglink) it is now converting that force to hydraulic pressure and then back to pure mechanical force which would then push on the steering arm (or the tie rod). But no matter how you look at it the pitman arm still ends up pushing on the steering arm and vica-versa. Hence the name the "fluid draglink". Where this system would really work well is for ultra high travel suspension systems because with this you could do whatever type of suspension setup you wanted. Right now with traditional steering the only way to completely eliminate suspension-cycle steering is to design the auspension arount the steering. You could now run anything from 1-link to 3 or 4-link or leaf springs all without ANY suspension-cycle steering no matter what crazy amounts of travel you have.

CTENG in KS · « **Reply #26 on:** Nov 24, 2006, 04:37:15 PM »

With all the "crazy" travel being designed in...why not just pop for a couple extra dolars and go full hydro? What nutzo suspension are you trying to run that you can't install a proper panhard bar? And what makes you think that this is going to be road worthy anyway?
If you aren't worried about road driving or racing, why are you so concerned with a bit of bumpsteer.
I am thoroughly confused.

blackdiamond · « **Reply #27 on:** Nov 24, 2006, 05:20:48 PM »

First let me say that I'm not sure I fully understand this thread, but I still have a question:

If you are connecting two hydraulic rams, one parallel to the frame and one parallel to the front axle, with the expectation that they will work together, won't they need to move different amounts depending on the individual geometry?

Hyena · « **Reply #28 on:** Nov 24, 2006, 06:08:43 PM »

but it still won't be legal for the road. to be legal you need a mechanical linkage from the box to the axle. that is why full hydrolic steering is not legal. it is a good idea and all. iam just trying to find all the stuff that could or is wrong. as i was saying before aboutthe cast steering box mount. it is just weak by itself, i am not saying it will put more pressure on it. but those cast mounts have been known to break a lot.

FIREBALL · « **Reply #29 on:** Nov 24, 2006, 09:59:07 PM »

Wow, I never thought i'd see this kind of pirate style bashing on this site. It wasn't all that long ago that some crusty old codger said what the hell do you need to go and cut out that perfectly good front end for and put that solid axle under there, or why do you need to do that cross over steering.
Come on guys.....the whole point of a board like this is to bounce ideas and be constructive.

Now...this system does work. I've seen it. Now I can't tell you how it would be on a daily driver but what the hell, give it a try.
Rhino doesn't live in Cali from what I gathered, so maybe it's not legal where he's at or maybe it is. But i'm pretty sure most of you are running rigs that are not really legal to be on the road either. So i'm not so sure why you're so concerned about that. I've seen plenty of rigs with fab work that I would leave the driveway with and those guys drive there trucks like they're sportscars.
Don't get me wrong here, safety is very important. There are some downfalls to this set-up, like losing a line, but with high pressure hydraulic lines the redundancy, pressure wise, would be very high, since the pressure in this system would be relatively low.
Let's not bash someone who wants to try something new, let's try and make it better if we can.
I say build it....let us know how it works.

RynothealbinO [OP]

RynothealbinO [OP]

RynothealbinO [OP]

RynothealbinO [OP]

RynothealbinO [OP]

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