First, conditions of this post: All legal matters not an issue, and no, I'm not thinking about running my truck on the street. It is just an idea that I thought about, mainly for my brother.

Is the reason that people say full hydro is unsafe on the street because, at high engine speeds, the pump is turning so fast that any small movement in the steering wheel results in instant and drastic/oversensitive steering changes? If so, could running an electric pump fix this? And if the electric pump turned too fast still, couldn't you just hook up a voltage regulator to it to slow it down?

J. J.

Regulating voltage through a DC motor to slow it down, is a bad thing for the motor. Read through a winch manual for what it says about winching on a low battery or with really long battery cables--it'll burn up the motor.

The orbital control valve controls flow to the cylinder--the faster you turn the wheel, the more fluid it flows. (sorta--that's not an engineering answer)

Full hydro tends to be twitchy on the street because it's usually set up at a relatively low lock-to-lock turn count. That will result in it feeling unsafe on the street.

Most people who say it's unsafe on the street, are saying so because:
1. There's no mechanical backup--if a line fails, you're heading for the ditch.
2. Few full hydro setups are set up with double rod cylinders--a different number of turns lock to lock right, than lock to lock left, is weird to get used to.
3. Relatively few control valves have a return to center allowance. This one gets into legality issues too, but basically, if you let go of the wheel, it's supposed to recenter itself--full hydro (unless it's designed to) usually won't.

If you're worried about having too much flow (with a PS pump, you won't, and with a typical orbital valve, you can't) through the valve, you can put a flow control valve in the circuit, and divert the "overflow" back to the reservoir. Reality is, you don't need to stress over that side of it--it's rare to have a setup that has too much flow. Not enough flow at lower engine RPM's, however, is a common problem with full hydro.

No mechanical steering linkages connected means NO steering in the event of any failure.

No, the reason is, no back up... You blow a hose, you and someone else are gonna die.

Im shure someone will correct me if im wrong here.It is my understanding that people dont run full hydro on street driven rigs because there is no mechanicle conection to steer you if you should loose pressure(like if a line broke).If you lost pressure your rig would go where it wants to.

I also belive that the turning speed has nothing to do with RPMs when you get over about 1000 it is constant.I dont think this is an issue?




Sorry to slow,but you get the point

The problem with full hydro on the street that I always see posted here is that there is no mechanical backup. If the engine stalls, you blow a hose, etc., you have NO steering. That's obviously not good at 60 MPH on a highway. With "normal" steering, you always have a mechanical linkage to make you turn. It may be hard to move 44s with manual steering, but it CAN be done. And it can make the difference between you breaking down and you causing a collision. Same problem with an electric pump, if the pump dies or the wires get disconnected, or the fuse blows, or, again, a hose blows, you have ZERO steering.

I tossed the idea of full hydro around last week. After more thought, I decided that full hydro on the road is a REALLY BAD IDEA. Sure, it's not likely to die right away if you built it right. But I've had PS hoses blow, pumps go out, etc. in situations that would have been life threatening if that were my only way to steer the vehicle.

lets look at your question from a differant angle

can you run an electric hydrolic pump instead of the engine mounted pump so that if the engine dies you still have steering?

granted if you pull a line or break something no more steering but will it work ?

full hydro with an orbit valve will still steer when the motor dies, but it will be very tough to turn

but if a hose were to blow, you and others would be screwed. :nuke:got insurance?

on second thought, what are you going to do if something lets go on your conventional, crossover or hi-steer steering? Probably kill someone... hi-steer arm shears off, comes loose :eek: ..... there are lots of possibilities....

What are the probabilities that a hydro line will burst on the freeway? And what are the probabilities of mechanical linkage letting go on the road?

two times now I have known someone personally that had a tie rod end come apart just going down the road. and on my t-bird I wa going straight down the road and the lower ball joint came apart and put me in the ditch. Maybee we should all get bikes and crush our trucks, because there will always be risk of mecanical failure that could be deadly. If you want to run full hydro I would just be very carful if you want to run it on the street. for examole keep an eye on it, use quality hoses and ends, use a double ended ram, keep the hoses out of harms way, just use some common sence.

John

while i have no experience with full hydro steering,, it seems to me to me that tie rod ends/rod ends and hysteer arms just could fail just as easy as a hose... how bout it farmers and heavy equipment operators when was the last time a hose failed on your equipment that was a just a fluke failures,,,bet the numbers are not much different.. my .02

I can answer in one word

MYTH !!

All the usual dumb-ass I don't know nothing responses about Hydro steering are wrong.

You CAN have manual steering ability should the engine quit
You CAN have very good return to center feel (load reactive)
You CAN have the proper "feel / speed" - it's all about selecting the proper valve

As far as the "mechanical backup"...I think that's horse-poop too. As if mechanical systems never fail! Not to mention - there are tons of people with no parking brakes or parking brakes that could never hope to stop them safely from 60mph, and you don't see people worried about those hyraulic systems failing with no (adequate) mechanical backup!

Also - what about all the heavy equipment that is full hydro...from huge mining trucks to loaders and graders and stuff....some of which does a fairly good clip down the highway??

[QUOTE]Originally posted by BillaVista
[B]I can answer in one word

MYTH !!

All the usual dumb-ass I don't know nothing responses about Hydro steering are wrong.

You CAN have manual steering ability should the engine quit
You CAN have very good return to center feel (load reactive)
You CAN have the proper "feel / speed" - it's all about selecting the proper valve

As far as the "mechanical backup"...I think that's horse-poop too. As if mechanical systems never fail! Not to mention - there are tons of people with no parking brakes or parking brakes that could never hope to stop them safely from 60mph, and you don't see people worried about those hyraulic systems failing with no (adequate) mechanical backup!


Good points, that is what i was thinkin, but if you set up hydro to steer that nice on the road would it still be the same no feel effortless off road.

Just for the record i have not intentions of driving my hydro steer at any high speed.

Ian-

Well, the power would be the same, so the effort would be the same (assuming same input torque required spec for the valve - there are different specs available), but you do have to compromise on the quickness (i.e. turns lock to lock)

For example, 4-5 turns lock to lock might be good for the street, but 2 might be nice and quick for the trail.

Essentially, once you know what you're doing, you can spec almost any kind of valve....but you need to learn a bit about hydraulics....or just tell Station what you want (in terms of performance) and he'll take care of the rest !

I take it there isn't an adjustable valve of any kind? You know, so you could run 4-6 turns to lock on the road to the trail, and then switch to 2 turns for the trail.. that would be nice.

I was reading on the pfd catalog for Char Lynn and they have a valve that is designed for compliance with highway standards etc... even when the motor dies it retains a "quickness" that is driveable...

I think any steering system needs to be well-designed and well-maintained and that's the bottom line. There is some ghetto fab out there that technically is okay, but really shouldn't be on the road because it's a loose cannon, and there are probably full hydro systems that work well enough on the road.

OK ... SCREW the discussion of mechanical backup and such! I know I asked why peopel thought it was unsafe, but I don't want to go down that tangent in this thread. We could argue all day about it. Plus, I don't care about granny and her little grandkids in the Geo Metro to my side when my steering goes out. When I die, I hope to take as many innocent bystandards with me as possible! :flipoff2: Preferably small children, old people, and kittens!

Is there a way to make hydro less hyper-responsive for on the road?

J. J.

put an adjustable flow valve on the pressure side of the orb. valve.

Originally posted by JOHNS351C
put an adjustable flow valve on the pressure side of the orb. valve.

I have a flow restrictor in the Return side to boost pressure when I'm lugging the engine, it works, but I'd rather have a bigger pump...maybe this winter I'll get around to it.

Is there a way to make hydro less hyper-responsive for on the road?

I already answered that.

YES. Pick the right valve!!!

Originally posted by patooyee
First, conditions of this post: All legal matters not an issue, and no, I'm not thinking about running my truck on the street. It is just an idea that I thought about, mainly for my brother.

Is the reason that people say full hydro is unsafe on the street because, at high engine speeds, the pump is turning so fast that any small movement in the steering wheel results in instant and drastic/oversensitive steering changes? If so, could running an electric pump fix this? And if the electric pump turned too fast still, couldn't you just hook up a voltage regulator to it to slow it down?

J. J.

Wouldn't a bypass be a solution to the problem you brought up?

any hydro system should have a pressure relief on it anyway, this will keep you from blowing seals, hoses etc....could also be used to prevent poppiung knuckles off of the axles. Most are adjustable so you could dial in the pressure you want. Plus I doubt the guys using a P/S pump for the hydro steer build enough pressure to worry about that problem.

On a side note.....

I think the hose failure thing is not near as big a deal as folks make of it. TRE, welds, ball joints, etc... fail all the time on the road and everyone wtill runs them.

The only down side I can see to the hose is that it tends not to give as much warning before it fails.

if you were to run full hudro on the street would you be beter off with a double ended ram or two single rams aposing each other. Of corse all leagl $hit aside.

go with the single double ended ram, it is simpler fewer parts and a cleaner setup.

Yeah but 5 times the cost of a single single ended ram. I don't quite understand how 2 single ended rams opposing each other would work. If the ram has longer thro in 1 direction then putting another ram opposit aint gonna make the first travel any farther. Am I understanding it right. Is it a physical limitation in the ram or is it a matter of the fluid? Do you run the lines in series or parallel?

Originally posted by JOHNS351C
go with the single double ended ram, it is simpler fewer parts and a cleaner setup.

maybe a pic will clear this up for you. this is a high dollar truck with a piece of shit rear steer system.

here is the other truck they had at the show.

Broncorob,

Like this: (the cylinders are on top marked L and R) One puches while the other pulls and vice versa.

http://www.rightcoastcrawler.com/billaVista/hydrosteering/2rams.jpg

Oh, and on the cost of the double-ended.

Have a chat with Station....when you add up the mounting hassles, extra plumbing and fittings, bracketry etc. the double-ended really starts looking nice and he can provide fabulous gear at really great prices. Knows his shiat to (taught me everything I know :D )

Originally posted by BillaVista
Oh, and on the cost of the double-ended.

Have a chat with Station....when you add up the mounting hassles, extra plumbing and fittings, bracketry etc. the double-ended really starts looking nice and he can provide fabulous gear at really great prices. Knows his shiat to (taught me everything I know :D )

Not that Station doesn't know what he's talking about, because he DOES know his hydro shit. But mounting hassles are about the same for both, IMO. You can't really calulate them in the cost anyway. Extra plumbing requires one more tube than a single ram which makes for 2 more fittings. My brother and I are getting ALL our hydro lines custom made at the local hydro store for ~$50/set, which is EXTREMELY good. Add another one for probably ~$10. So that's an overall addition of $10 + a $50 ram compared to a double ended ram. Last I heard, double ended rams start around $300. And bracketry is $5 in 3/8" steel. So compare $165 to $300+. That's enough savings for me to justify 2 rams instead of a double ended. (Like I even care. I'm fine with getting used to an extra turn to one side. It's no big deal.)

J. J.

You CAN have manual steering ability should the engine quit

How does this work with full hydro?

How does this work with full hydro?

To be honest, I'm not sure of exactly how it works in terms of the hydraulic circuit, without looking it up.

But I do know it's listed as a feature or option of just about every steering valve in the Char-Lyn and Danfoss catologues.

And it makes sense....think of how many industrial vehicles have hydro steering, and their engines sometimes quit too. You wouldn't want to be towing a 747 up to the gate, have the engine stall, and lose all steering !!!!!

Originally posted by BillaVista
I can answer in one word

MYTH !!

All the usual dumb-ass I don't know nothing responses about Hydro steering are wrong.

You CAN have manual steering ability should the engine quit
You CAN have very good return to center feel (load reactive)
You CAN have the proper "feel / speed" - it's all about selecting the proper valve

As far as the "mechanical backup"...I think that's horse-poop too. As if mechanical systems never fail! Not to mention - there are tons of people with no parking brakes or parking brakes that could never hope to stop them safely from 60mph, and you don't see people worried about those hyraulic systems failing with no (adequate) mechanical backup!

Also - what about all the heavy equipment that is full hydro...from huge mining trucks to loaders and graders and stuff....some of which does a fairly good clip down the highway??

Wow. Sure are a know it all!:rolleyes:

The brakes not having a mechanical backup is not same issue. Typically, brakes dont just all of a sudden quit working. I still had brakes after I ripped both rear calipers off, and ripping the lines apart. You also have engine braking, and the chance that you parking brake does work. Biggest differece is, you still have directional control of the vehicle, and chances are, you wont head on another driver.

Originally posted by azk5
You CAN have manual steering ability should the engine quit

How does this work with full hydro?

There is a small gear pump in the end cap of the orbit valve.

Originally posted by dirtrod


There is a small gear pump in the end cap of the orbit valve.

What action drives the gear pump?

Your elbows and shoulders when you turn the steering wheel

Wow. Sure are a know it all!

All? No. Quite a lot? About some things, yes. More than you? Seems clear enough! :flipoff2:

Typically, brakes dont just all of a sudden quit working.

Niether do properly maintained hydraulic steering systems...thank you for making my point!

Look mate, I'm not trying to pick on you, but I CAN'T STAND IT when people spread myth and misinformation as if it were fact. Ignorance sucks! Have you, or any of the other "Hydro is bad / unsafe" touters any idea how many vehicles have full hydraulic steering, from road to construction to mining equipment to aircraft tugs and big / fast crash/fire/rescue trucks?????

Yeah great, so now I've seen pictures of using 2-single ended rams opposing each other like I haven't seen pics before. It does nothing to explain what makes up the difference in turns from center to lock. I guess to put it simply: why does the single ended ram turn more in one direction.

Originally posted by BillaVista

Look mate, I'm not trying to pick on you, but I CAN'T STAND IT when people spread myth and misinformation as if it were fact. Ignorance sucks! Have you, or any of the other "Hydro is bad / unsafe" touters any idea how many vehicles have full hydraulic steering, from road to construction to mining equipment to aircraft tugs and big / fast crash/fire/rescue trucks?????

BillaVista I have to agree with you here, as a farm boy I have run multitudes of equipment running full hydro steering...and yes they do fail if you tear off a line etc...But I can count in ALOT of years how many times I have had that happen on one finger...and it was a poorly maintained hyd hose that caused the failure. Plain and simple it was neglect. Now I am not sure I am much of a fan of HYD steering a 4x4 rig thats ever going to do DD duty....and will be the first to admit maybe a walk around and a glance at hoses and fittings before a road cruise to another trail is possibly a great idea...but I am gonna stick my neck out here and make a comment...In all the bickering of safety here, a few things I believe keep getting lost in communication. HOW many rigs are running around the street with single sheer mounting on rod ends in steering application..last I checked if ya lost a rod end anywhere in yr steering your going to have a fun ride with no control...or how about a rag joint? Again NO control....is it really any differant than hyd? I will not even comment how many trail rigs I have seen with sheered bolts, broken rod ends, failed high steer mounting, rag joints, and so many other situation that ALSO will cause the same loss of steering control.

NoRM

>Yeah great, so now I've seen pictures of using 2-single ended >rams opposing each other like I haven't seen pics before. It >does nothing to explain what makes up the difference in turns >from center to lock. I guess to put it simply: why does the single >ended ram turn more in one direction.

Cause the ram has a different piston area and therefore volume on either side. The shaft takes up some space.


Next, Eaton/Char-lynn make a valve that is approved for German TUV road use that switches to a low displacement mode when the hydraulic pump fails. This means proper lock to lock at full pressure and way more turns lock to lock when no external pressure ie you can turn the thing.

Ken

Originally posted by broncorob
Yeah great, so now I've seen pictures of using 2-single ended rams opposing each other like I haven't seen pics before. It does nothing to explain what makes up the difference in turns from center to lock. I guess to put it simply: why does the single ended ram turn more in one direction.

Sorry, I haven't been any help in this thread I have been very busy lately with building up my home shop, going to work, and answering tons of e-mails/phone calls about hydro steering every day.

I haven't had much time for the Pirate board lately, and if I am on Pirate, I am usually on the phone.

I didn't have work today, so here I am(I need to be working on my shop though).

broncorob, Slowzuki did answer your question, but I will try to answer it with a little more detail so hopefully you understand it well.

A hydraulic steering valve puts out a certain amount of fluid whether you turn left or right. In both directions the flow from the valve is equal.
The reason why you have unequal turns in a single ended steering cylinder is because there is unequal volume on either side of the piston. One side of the piston has the rod that extends out of the body that takes up space within the body on that side of the piston. The other side of the piston has the full area of the inside of the cylinder body that can be filled with fluid.

The unequal volumes on either side of the piston means that it takes the steering valve less revolutions to fill the small side than the large side. That is why it takes less turns of the steering wheel to steer to full lock in one direction than in the other.

For example. With a standard 2" bore 8" stroke single ended cylinder , that has a 1 1/8" rod, the large side of the piston has 68% more volume than the small side. The amount of turns of the steering wheel will accordingly be 68% more in one direction than the other ,no matter what displacement valve that you use.
So if you were using a 5in^3 per revolution valve and the said steering cylinder you will have 2.5 turns from center to lock on the large side, and only 1.7 turns from center to lock on the small side. If you were steering lock to lock it would take 5 turns of the steering wheel in one direction, and only 3.4 turns in the other direction. You can really see the difference in lock to lock steering.

One other important thing to note using the numbers that I have already put up is that if you were steering lock to lock on the large volume side it would take 5 turns of the steering wheel, but to steer back to center you will be using the small side of the steering cylinder so it will only take 1.7 turns to steer back straight.

With a single ended steering cylinder you can never know where your tires are based ion the steering wheel, because the relationship between the two is never the same. It is always changing. This is especially important for those of you that would like to use nice steering wheels that are anatomically correct, or those that have steering wheels with controls in them. The likelihood of your steering wheel pointing straight ahead when you actually are going straight ahead is small.

The reason that dual single ended cylinders balance out the fluid volume is because they are installed with opposite sides of each cylinder tied together. So the small side of one cylinder is coupled to the large side of the other, and vice-versa. This type of system has a very large cylinder volume, which will require a high displacement per revolution valve to have reasonable steering ratios. You can reduce the cylinder volume by using small size cylinders to make up for having dual cylinders, but the problem with this is that small bore cylinders aren't extremely common, so they usually cost quite a bit more than the more standard sized single ended cylinders. Another problem with this system is that for most applications it takes up allot of space, and/or is hard to get correct geometry.

That is where the double ended steering cylinder comes in. It gives equal performance that you would have with equal volume dual, single ended, steering cylinders, but takes up less space, is easy to get the geometry right, and an added advantage is that you no longer need a tie rod. A double ended cylinder will end up costing about the same a dual single ended setup, so the deciding factor between the two is which works best for you.

Well, time for me to go superglue my finger tips back on after all of this typing .
Hopefully I have helped some to have a better basic understanding of hydraulics in conjunction with the effect that will be had in your vehicle.

I did not go into steering force at all, only into volume, so if anyone has questions regarding the various possibilities, and the difference in steering force, then I will go into that when I have time.

Later,
Sean

Originally posted by broncorob
Yeah great, so now I've seen pictures of using 2-single ended rams opposing each other like I haven't seen pics before. It does nothing to explain what makes up the difference in turns from center to lock. I guess to put it simply: why does the single ended ram turn more in one direction.

OK. If you imagine the bore of the ram, or, in other words, the space inside the ram that has to be filled up with fluid, the concept is simple. You have the cylinder that has to be flooded with fluid, but it's not just a full cylinder. Some of the space is taken up by the actual ram rod that goes in and out of it. When the ram/rod is all the way in, the space that needs to be filled up is constant. But as the ram goes out of the cylinder, it creates more space behind it where it used to be that then needs to be filled up with fluid. The further out the ram goes, the more space that used to be taken up by the ram needs to then be filled with fluid. Therefore, when you're steering straigth ahead, the ram is ideally half in and half out. To push it out you have to displace more fluid as a result of the ram rod leaving the cylinder. But as it goes in, less fluid has to be displaced. One direction you're going in and the other you're going out, which result in asymmetric steering.

What having two rams accomplishes is canceling out the lost fluid displacement in one ram by the gained displacement in the other. You mount them so that, when one is going in, the other is going out.

Double ended rams are basically 2 rams in one cylinder, accomplishing the same effect. When one end goes in, the other goes out, and vice-versa.

Have I explained it clearly?

J. J.

I'm not really polished up on all of this anymore, but lets say you're arguing to yourself about running single acting vs double acting cylinders in your steering system. You've narrowed it down to two cylinders. They have a 2x8" i.d. with a 1" shaft (just for the sake of arguement)

The double acting cylinder would have a swept area on either side of the piston of around 2.4649 square inches...

The single acting cylinders in opposing directions, would have a combined area of 12.3245 square inches on the pistons (9.8596 + 2.4649)

If you applied 2500 psi to the double acting set up, you'd come out with 6200 pounds of force at a measureable point in the steering linkage (we're not accounting for drag or mechanical advantage and losses here)

If you applied 2500 psi to the single acting system, you'd come out with 30,800 pounds of force at the end of the same linkage, which I think would break most anything you gave it the chance to on all but the strongest of knuckles...

If you applied 500 psi to both of the opposing single acting cylinders you'd come out with approximately 6160 pounds of force at the end of the linkage, which, is awfully damn close to the double acting set up, but at a much safer 2000 psi lower. You'd obviously have to flow more oil to actuate the cylinders, but I'm sure that wouldn't be a problem. You'd run a longer lasting system that would operate a bit cooler than anything that runs at 2500 psi. It may be less touchy on the controls, but it also may be more prone to its own form of bumpsteer...

With 2 cylinders, you're adding double the possible problems into the steering system, but at the same time you're taking away some of the higher pressure induced problems thay will occur at 2500 psi.

Of course, like I said I'm not as polished up on this as I used to be, so I'm open to arguements or honing of my math skills. Anybody else have anything to say about this?

Originally posted by MR4WD
I'm not really polished up on all of this anymore, but lets say you're arguing to yourself about running single acting vs double acting cylinders in your steering system. You've narrowed it down to two cylinders. They have a 2x8" i.d. with a 1" shaft (just for the sake of arguement) sni[p



So is this one of those BS posts you stay awake dreaming up or are you serious?

i work on heavy equipment and they have a nitrogen pressurized backup hydraulic systems. you may be able to incorporate one of these smaller systems on your vehicle, look at Caterpillar loaders. Hydraulic hoses dont normally explode, they develop a leak before failing completely.

Originally posted by dogbender
Hydraulic hoses dont normally explode, they develop a leak before failing completely.

This newbie knows what he's talking about!

J. J.

Originally posted by MR4WD
I'm not really polished up on all of this anymore, but lets say you're arguing to yourself about running single acting vs double acting cylinders in your steering system. You've narrowed it down to two cylinders. They have a 2x8" i.d. with a 1" shaft (just for the sake of arguement)


I think you have your terms mixed up. When using dual single ended cylinders in a steering system, you still use DOUBLE ACTING single ended cylinders.

Sean

Yes, of course. Wrong terminology, but the premise will stay the same, right?