Legal almost full hydro?

jsudar

Well-Known Member
Location
Cedar Hills
Kake's hydro thread got me thinking about building an almost full hydro steering.

The law states you have to have a mechanical links that operate the steering, so full hydro is illegal on the road. However, I'm thinking in a crossover steering application you could keep the steering gear and drag link, but replace the tie rod with a double ended ram. The tie rod would just be in three pieces and the middle one would happen to have a piston and sleeve around it, but it would still be mechanically linked together.

You would still have to use the valving in the steering gear to control the ram, rather than using an orbital valve, which is not ideal, but ok.

Maybe you could put some pressure reducers in the lines to divert most of the pressure to the DE ram instead of to the piston in the gear box. That way the drag link would be there as a fail safe and something to keep you street legal, but most of the steering forces would be seen by the DE ram and not the drag link and box.

Am I on to something here or am I just over-complicating things? (like I usually do)
 

Corban_White

Well-Known Member
Location
Payson, AZ
Like this?

DEHydroAssist02.1005.jpg


Here is the thread, start at post 33:
http://www.fullsizechevy.com/forums/general-discussion/offroad/197160-hydro-assist-2.html
 

UNSTUCK

But stuck more often.
How do you sinc the gear box output ratio with the travel speed of the ram? Or do you need to even worry about it? I wonder if one would cause the other to be forced to speed up slow down or bind ect. I guess they don't with hydro assist systems, so you may be okay. Something to think about.
 

bryson

RME Resident Ninja
Supporting Member
Location
West Jordan
Pretty sure it would still be illegal because your tie rod (DE ram and tie rods) is not gonna fly for a mechanical connection between the wheels. The ram needs fluid and pressure to be functional as your tie rod, whereas a hydro assist setup can still be used (not good for it, but you can still steer...) even if there is no fluid or pressure in the system. Plus, if you still have a steering box and a drag link, it isn't full hydro anyways, it is just a really odd, poorly functioning hydro assist.
 

kake

Registered User
Location
Kaysville
interesting

Has anyone ever hooked up a double-ended ram to a steering box? I would imagine it woul be very slow, but I am not for certain. If it would work, it could pose another option for hydro assist set-ups. I would be surprised if someone on this site hasn't at least tried it. It is also mechanically linked if you should lose pressure.
 
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Tacoma

Et incurventur ante non
Location
far enough away
This:



Pretty sure it would still be illegal because your tie rod (DE ram and tie rods) is not gonna fly for a mechanical connection between the wheels. The ram needs fluid and pressure to be functional as your tie rod, whereas a hydro assist setup can still be used (not good for it, but you can still steer...) even if there is no fluid or pressure in the system. Plus, if you still have a steering box and a drag link, it isn't full hydro anyways, it is just a really odd, poorly functioning hydro assist.
 

jsudar

Well-Known Member
Location
Cedar Hills
Yeah, I was think something similar to what Corban posted.

The reason I think it would be legal is because the shaft on a DE ram goes all the way through the ram. The piston is in the middle of the shaft and gets shoved back and forth, but since the shaft is solid it is all connected.

Think of it as a really burly power rack and pinion, but without the rack and pinion part,
 

Unichev

Registered User
Location
Ogden, Utah
First Off, Not sure where the law has "Stated" that there needs to be a mechanical linkage. That's an old wives tale. So Full Hydraulic sits in the same area as beadlock wheels as far as being legal. That doesn't mean that you just throw a bunch of **** together and run it. A fully balanced system will work just as well, or better then a crossover system. I did it on the Blue truck and it had a balanced cylinder with a load reactive Orbitrol valve. The steering feel was really nice and had return to center just like the mechanical linkage has.

As far as using a Double ended cylinder in place of the tierod. I did it on the Crew Cab and I like it better then the Single ended cylinder I had on the blue truck at first. With the double ended cylinder you have equal speed and power both directions. Its a little harder to setup up, but I hated how my blue truck would be a little slow on one side and just right on the other.

Not really sure why you would think the double ended cylinder would be a "poorly functioning Hydraulic assist". It isn't, but explain why you would think it would be.
 

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jsudar

Well-Known Member
Location
Cedar Hills
You may be right-- I haven't looked at a safety inspection book for a long while and I don't spend a lot of time reading laws... several people have told me that most race sanctioning bodies (except in rock crawling/racing) require a mechanical linkage. But again that's still hearsay.

Maybe I'll have full hydro sooner than I thought.
 

bryson

RME Resident Ninja
Supporting Member
Location
West Jordan
Not really sure why you would think the double ended cylinder would be a "poorly functioning Hydraulic assist". It isn't, but explain why you would think it would be.

The situations you have described on your rigs sounds like they work well, but they are full-hydro setups. They are not hydro-assist because you are not "assisting" anything, but rather doing the entire job via hydraulic pressure. In a hydro-assist setup, there is just a little extra push/pull from a ram attached to an already functioning conventional steering setup - hence the assist. The reason I said that a DE ram would make for a poor choice in a hydro-assist setup is because every DE steering ram I have ever seen is big. 2"+ diameter (usually at least 2.5".) To make a ram that size move, you need a lot of fluid volume at high pressures. They work on full-hydro setups because the ram is the only part of the system that requires fluid pressure. On a hydro-assist setup, you already have a steering box that has build in hydraulic assist (that's why it is called "power steering," which requires a great amount of fluid pressure and volume to function,) and also you are using the steering box itself to act as the steering valve. The design of a standard PS setup is such that they do not have the ability to move enough fluid at high enough pressures to work a ram that big. There are even volume issues on most hydro-assist setups with 1.5" rams, and they don't take half the fluid a DE ram needs.

Also, the manuals may not specifically state that full-hydro is illegal, but good luck finding a safety inspector to sign it off.

What happens if your engine dies, or if a hydraulic line bursts??? 65mph on the freeway, you run out of gas, engine dies which means your power steering pump stops pumping. That means no pressure for your steering! Turn the steering wheel all you want but nothing is gonna happen other than you are now doing 65mph with no steering. Sound safe to you? I sure don't want a rig with full-hydro on the street... The reason people say it has to have "mechanically connected linkage" is for these reasons. Engine dies or line bursts, at least you can still control the vehicle.

And the reason beadlocks generally aren't legal? Look for a DOT stamp on the wheel. If there is one, you're fine. If not, you're effed (if you get caught;))

Some beadlock wheels have the stamp (AEV) and some beadlocks work with your already legal existing wheels (Stauns, InnerAir...) so those would be fine. Most beadlocks don't have the stamp, so they aren't legal.


I'm not trying to be mean about any of this... so please don't take it as so.:) But I do hope this helps.:cool:

Phew.
 
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kake

Registered User
Location
Kaysville
You may be right-- I haven't looked at a safety inspection book for a long while and I don't spend a lot of time reading laws... several people have told me that most race sanctioning bodies (except in rock crawling/racing) require a mechanical linkage. But again that's still hearsay.

Maybe I'll have full hydro sooner than I thought.

Ya, I am not even really worry about the legal part as much as I am worried about the safety part. I intend to go high speeds both on and off the road with my kids. That is why I insist on assist????? Neverthe,less everything I have heard against you idea are all assumptions. I would like to hear from somebody who has tried it. That dude on the fullsizechevy link is doing exactly what you were talking about. I will be watching to see how it works out for him.
 

Unichev

Registered User
Location
Ogden, Utah
The situations you have described on your rigs sounds like they work well, but they are full-hydro setups. They are not hydro-assist because you are not "assisting" anything, but rather doing the entire job via hydraulic pressure. In a hydro-assist setup, there is just a little extra push/pull from a ram attached to an already functioning conventional steering setup - hence the assist.
The picture above shows a Hydraulic Assist steering system on my 84 Crew Cab Chevy. The cylinder is only there to "Assist" the box. Just because it uses a double ended cylinder as the tierod does not mean if falls into the full Hydraulic steering category. The tires are still controlled mechanically.

The reason I said that a DE ram would make for a poor choice in a hydro-assist setup is because every DE steering ram I have ever seen is big. 2"+ diameter (usually at least 2.5".) To make a ram that size move, you need a lot of fluid volume at high pressures. They work on full-hydro setups because the ram is the only part of the system that requires fluid pressure. On a hydro-assist setup, you already have a steering box that has build in hydraulic assist (that's why it is called "power steering," which requires a great amount of fluid pressure and volume to function,) and also you are using the steering box itself to act as the steering valve. The design of a standard PS setup is such that they do not have the ability to move enough fluid at high enough pressures to work a ram that big. There are even volume issues on most hydro-assist setups with 1.5" rams, and they don't take half the fluid a DE ram needs.

Usually the single ended cylinders are actually too big. They just happen to be cheaper. If you do the math though, my cylinder actually takes about the same amount of fluid to work as one of the smaller cylinders. A 1.5" bore-5/8 rod single ended cylinder has a surface area of 1.460 sq. inches on the shaft side(the faster side), and 1.766 sq. inches on the non-shaft side(the power side). My 2.0 bore-1.25 rod shaft has a surface area of 1.914. Which is a little more then the power side. The 1.5 cylinder works ok with the stock pump. I hopped mine up with the pump mods to help with the more volume it needs with the larger surface area. Mine works great, 1 finger steering. Even my 3 year old can steer it. And this is with Hydroboost also.
Also, with the Double ended cylinder you dont have the difference in power and speed like a single ended cylinder. And with a full hydraulic you are not turning 2 to the left and 2.5 back to the right.

Also, the manuals may not specifically state that full-hydro is illegal, but good luck finding a safety inspector to sign it off.
Well, since I had my truck registered for 2 years with full hydraulic steering I dont think it will be a problem. I was also pulled over by a sheriff and a Highway Patrolman. Neither of them said a thing about the steering. They just cared about the no mud flaps.

What happens if your engine dies
You steer just like you would any other steering system. The "Correct" Orbitrol valve will let you steer even without the engine running. Its just harder like any other steering system.

or if a hydraulic line bursts???
What if a draglink end fails or a sector shaft breaks? The chances of those breaking are greater then a hydraulic line. As long as you use a quality hydraulic hose and keep it from rubbing on stuff you will never have a problem. If you see that its wearing somewhere, just replace it like you would if a draglink was wore out.


65mph on the freeway, you run out of gas, engine dies which means your power steering pump stops pumping. That means no pressure for your steering! Turn the steering wheel all you want but nothing is gonna happen other than you are now doing 65mph with no steering. Sound safe to you?
No, it doesnt sound safe, but it doesnt describe a Quality and Balanced hydraulic steering system that well. It describes a Fork lift Orbitrol valve and a single ended cylinder with poor quality hoses.

I sure don't want a rig with full-hydro on the street... The reason people say it has to have "mechanically connected linkage" is for these reasons. Engine dies or line bursts, at least you can still control the vehicle.

Who are these "People"? Who ever they are, they are misinformed about a Balanced and Quality Hydraulic steering system. They can turn when the motor dies. They take the same amount of turns left and right. The have road feel(The wheel will return to center when you are coming out of a turn.) You just dont take a steering system off of a forklift and expect it to be road worthy. Offroading you can do it however you want, but on road you need to know how to put a Hydraulic steering system together.

And the reason beadlocks generally aren't legal? Look for a DOT stamp on the wheel. If there is one, you're fine. If not, you're effed (if you get caught;))
Some beadlock wheels have the stamp (AEV) and some beadlocks work with your already legal existing wheels (Stauns, InnerAir...) so those would be fine. Most beadlocks don't have the stamp, so they aren't legal.
Beadlocks being Illegal fall in the same area as Full Hydraulic steering. I have not seen where it says that "Beadlock wheels are illegal", but everybody insists that they are. Again, was pulled over by a Sheriff and Highway Patrol and they didnt say anything about the Beadlock wheels.

I also drove my Full Hydraulic Steering truck with Unimogs down to Moab 5.5 hours each way. 75mph all the way no problem. Didnt kill a bus load of nuns or anything. Maybe a raccoon or rabbit though.

I'm not trying to be mean about any of this... so please don't take it as so.:) But I do hope this helps.:cool:
Phew.

As long as you dont call me a Fat boy I am not mad.
 
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kake

Registered User
Location
Kaysville
First Off, Not sure where the law has "Stated" that there needs to be a mechanical linkage. That's an old wives tale. So Full Hydraulic sits in the same area as beadlock wheels as far as being legal. That doesn't mean that you just throw a bunch of **** together and run it. A fully balanced system will work just as well, or better then a crossover system. I did it on the Blue truck and it had a balanced cylinder with a load reactive Orbitrol valve. The steering feel was really nice and had return to center just like the mechanical linkage has.

As far as using a Double ended cylinder in place of the tierod. I did it on the Crew Cab and I like it better then the Single ended cylinder I had on the blue truck at first. With the double ended cylinder you have equal speed and power both directions. Its a little harder to setup up, but I hated how my blue truck would be a little slow on one side and just right on the other.

Not really sure why you would think the double ended cylinder would be a "poorly functioning Hydraulic assist". It isn't, but explain why you would think it would be.

I didn't notice the draglink in the picture until your last post. I believe this is exactly the set up jsdar was referring to. Would love to know more details of the set up and how it works. Any issues at all, or issues you encountered? I am just trying to decide to go DE ram or single ram but I really want some kind of mechanical linkage. To me it seemed as though the DE would be more responsive for the reasons you stated. The DE would be also be balanced in both directions. Last but not least, in my particular application it would give me the clearance I need. However, my concern was volume flow through a steering box keeping up. I have seen many pumps burn up and want to avoid this as well. I do have an AGR high flow pump on hand though.
 
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kake

Registered User
Location
Kaysville
You may be right-- I haven't looked at a safety inspection book for a long while and I don't spend a lot of time reading laws... several people have told me that most race sanctioning bodies (except in rock crawling/racing) require a mechanical linkage. But again that's still hearsay.

Maybe I'll have full hydro sooner than I thought.

Found this quote from Four Wheeler website:

Full Hydro DOT Legality?
Someone started a rumor about fully hydraulic steering being illegal for use on the highway. This is not true. We contacted the U.S. Department of Transportation and asked about the rules on hydraulic steering systems. We were told that any rules prohibiting the use of fully hydraulic steering systems in the automotive aftermarket would fall under local laws. We suggest you check with your state's local transportation authorities if you question the legality of hydraulics.
 

jsudar

Well-Known Member
Location
Cedar Hills
^^^^^^ I read that last night too. I was going to dig out my old safety inspection book from when I used to do them, but couldn't find it.

I had some of the concerns bryson was explaining, like the pump not moving enough fluid or the valving in the steering gear not moving enough fluid. I can see where you're coming from.

I have a vague idea of how the orbital valve works and what the cubic inch rating means, but I'm not sure how it compares to a saginaw box. I tried to find some info on saginaw boxes, but I didn't have much luck.

By the way, the setup Unichev has is exactly what I am talking about. It seems to be working fine for him, so I think I'll give it a shot. Thanks for your input Unichev.
 

cruiseroutfit

Cruizah!
Moderator
Vendor
Location
Sandy, Ut
Guess I was wrong on the Beadlocks.

Your not wrong, that wording only appears as "reject when bead lock wheels are installed", yet there is no law in the state of Utah prohibiting their use. I know the UHP is charged with developing a manual and is given the authority to enforce them as they see fit, however its my assertion that without an actual law, you haven't done anything illegal.

Steering could be interpreted the same way. It references all your ends and such must meet OEM specs, hydro in any fashion won't meet factory specs :D However much like the beadlocks, there isn't an actual law prohibiting it. Could a ticket be written of course, could a good case be made, absolutely.
 

kake

Registered User
Location
Kaysville
Liabilty

One final thing to consider....liabilty. If you are driving a modified vehicle, that is even in the "gray area" on a public road and it causes any harm to another person, you're screwed. Insurance companies/ lawyers would try and take you to the cleaners. I guess I am saying use your best judgement to ensure everything is sound.
 
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