Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Full Hydraulic steering Safety?

Discussion in 'The Garage' started by ssped, Oct 1, 2006.

  1. ssped

    ssped 1/2 ton status GMOTM Winner

    Joined:
    Jan 5, 2006
    Posts:
    1,529
    Likes Received:
    0
    Location:
    Mission Viejo
    Why is full hydraulic steering unsafe? All the web sites mention it but nothing explains why it is unsafe? is it unreliable?
     
  2. big dan

    big dan 1/2 ton status Premium Member

    Joined:
    Aug 1, 2005
    Posts:
    2,656
    Likes Received:
    29
    Location:
    Arkansas
    one reason is that if you have a leak or rip a hose and lose your fluid you lose the ability to steer. with hydro assist you will still have the manual linkage to control the truck.
     
  3. gmc4cw

    gmc4cw 1/2 ton status GMOTM Winner

    Joined:
    Jul 19, 2006
    Posts:
    3,907
    Likes Received:
    0
    Location:
    west chester, Pa
    most people think it is unsafe but have no founding for it. on the street you will need some type of return to center feature to keep it legal. Reliability is the responsibility of the designer/installer. the higher quality of parts you use the more reliable. the lastest Fourwheeler just did an article on this.

    Yes fully hydraulic steering can be legal. In pennsylvania it is as long as you have a return to center. this can be accomplished with a coilover steering stabilizer.
     
  4. koldsimer

    koldsimer 1/2 ton status GMOTM Winner

    Joined:
    Jan 10, 2005
    Posts:
    1,480
    Likes Received:
    0
    Location:
    texas
    Yeah that's gonna work real well if your in the middle of a turn. "Oh, gee, my hydraulic hose just sprung a leak... good thing it's returning to center sending me right for that tree." No founding for it being unsafe? Did you actually read what big dan wrote? MECHANICAL LINKAGE in case of a hydraulic failure. Hydro assist is the safest for any street driven rig.
     
  5. Blazr77400

    Blazr77400 1/2 ton status

    Joined:
    Aug 31, 2001
    Posts:
    652
    Likes Received:
    0
    Location:
    Ogden, UTAH
    Its a good thing Draglinks, or rag-joints dont ever break!! :surepal:
     
  6. gmc4cw

    gmc4cw 1/2 ton status GMOTM Winner

    Joined:
    Jul 19, 2006
    Posts:
    3,907
    Likes Received:
    0
    Location:
    west chester, Pa
    I don't disagree with hydro assist being the safest. When was the last time you had a brake line fail? same thing. anything can fail. If hydraulics were unsafe or unreliable then the medium duty and construction industry would use something better.
     
  7. ntsqd

    ntsqd 1/2 ton status

    Joined:
    Nov 28, 2002
    Posts:
    3,381
    Likes Received:
    0
    Location:
    So. CA
    Yesterday, looks like a snake that just caught lunch. Nice & clean looking on the outside too.

    Full hydro is not something I'd do and it's not something I want to meet on the highway, but I've no doubt that when everything is new and good condition that it can be reasonbly safe.
     
  8. koldsimer

    koldsimer 1/2 ton status GMOTM Winner

    Joined:
    Jan 10, 2005
    Posts:
    1,480
    Likes Received:
    0
    Location:
    texas
    That's the thing... sure it's a fundamentally safe thing when it's functioning properly and in good shape. I sure don't want the car in front of me hitting something laying in the road and it toppling on the way to take out a hydro line. It could be real bad news to say the least.
     
  9. DEMON44

    DEMON44 Low-Tech Redneck

    Joined:
    Jan 8, 2003
    Posts:
    7,232
    Likes Received:
    15
    Location:
    Okotoks, Alberta
    I work with hydrauilcs all day long in the oilfield on drilling rigs, Wellhead stimulation equipment and support equipment and trucks.

    I'll tell you hydraulic hose is tough its nothing like a brake line....well similar in that its basically a form of rubber and steel, but far superior. The hose casing on our rigs is actually fire resistant.

    most bigger forklifts are full hydro steer........I've never had one fail and I...everyone beats the life out of company forklifts. regualr maintenance and inspection. replace as neccissary.


    I'd have very little consern about a well built properly engineered full hydro system on the street. Its usually people that have little knowledge about the subject that are afraid or it. I;ve broken tierods while driveing sucks ass.

    mechanical conection undermaintained is NO better than a fluid connection undermaintained. and properly maintained both are equally reliable.
     
  10. bigbluesuburban

    bigbluesuburban 1/2 ton status

    Joined:
    Feb 8, 2006
    Posts:
    1,362
    Likes Received:
    0
    Location:
    Constant State of Perpetual Anger
    Full Hydro... Like everything we do on our rigs, can be safe if properly maintained, but can be a disaster waiting to happen if not maintained properly.

    I do not know the legality in my state or anyone elses for that matter, but I think that a properly designed and maintained full hydro steering system could be excellent.

    I think that things like properly routing the hoses, and perhaps keeping the rubber sections to a minimum and perhaps even steel braided covers would make it very safe. If the steering were treated like a braking system with same precautions and safety measures then I think it would be perfectly safe.
     
  11. DEMON44

    DEMON44 Low-Tech Redneck

    Joined:
    Jan 8, 2003
    Posts:
    7,232
    Likes Received:
    15
    Location:
    Okotoks, Alberta
    I'll get some cross sections of our hydraulic hose from work when I'm in next. steel outter braid is not found in hydraulic hose. our standard is a steel double braid all braids are internal like a steel belted radial tire. but theres 1 wire 4 wire 5 wire 6 wire......6 wire we call rubber pipe.

    I'll give you an example 2 wire hydraulic hose, take a hack saw and start cutting into it..........I've done it, and I've given up before getting all the way through. logistically the only wat to do it is woth a power tool and rotating blade.

    Its tough very tough. people don't realize that. now the hose ends are a different story. If you use JIC swivel ends those would be your weak point., high pressure rating but can be broken off fairly easily. NPT lower pressure rating but much stronger physically= harder to break off.
     
  12. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

    Joined:
    Dec 21, 2005
    Posts:
    984
    Likes Received:
    0
    Location:
    Corn Country
    It's true that some folks are on a shoestring budget and yet use equipment that they either can't afford to properly maintain or just don't take the trouble to do regular inspections and PM.
     
  13. wayne

    wayne 3/4 ton status

    Joined:
    Feb 1, 2001
    Posts:
    6,178
    Likes Received:
    0
    Location:
    Carlisle, Pa
    This Jeep had full hydro. Broke a fitting, and snapped a rear driveshaft u joint, 15 minutes later it still had enough steering to get back on the trailer. It is highly unlikely that a line would ever blow to where you could not get it off the road. Would I trust it on the street, YES. If I had it to do over again I would have just went with full hydro.
    [​IMG]
     
  14. Citizen Rider

    Citizen Rider 1/2 ton status

    Joined:
    May 5, 2005
    Posts:
    1,415
    Likes Received:
    0
    Location:
    Plano, Texas
    it can be trusted if built well...But i have come to learn one thing, responce is not as good as stock steering...

    Think of it like this-
    Your going along the road following a car. The car rear ends the car stopping infront of it...You need to swerve to miss the car. You jerk to the right(so to speak) and when your in the clear of the next lane you pull it back to the left to straighten up....What happens? The ram now has to stop the 1 direction it was quickly pumped to, and push the fluid just pushing the ram back into the pump. So it is quickly fighting it self as the pump switches itself around. And while trying to get the fluid out of one side quickly its trying to pump it into the other side....making it a very slow return to straight from previous forces..

    I have done exactly what i stated above with my hydro assist, which sent me over a curb and into a street sign. you catch up to the ram, its not going to be just as fast as it is with turning a corner with a slow return..
     
  15. longbedder

    longbedder 1/2 ton status Premium Member

    Joined:
    Oct 26, 2005
    Posts:
    4,201
    Likes Received:
    363
    Location:
    Ridgecrest, CA
    Regardless of the reliability of the full-hydro system, it is single-point, less-than-catastrophic failure fallible by design. The important part is that this single failure need not be catastrophic to render the vehicle uncontrollable.

    A catastrophic failure would mean something like a broken tie rod or a wheel falling off. Something major broke in an atypical fashion. This is usually due to operating the part well outside its intended design envelope or severe lack of maintenance.

    A less-than-catastrophic failure would be things like the engine dying or a v-belt driving the pump failing, etc. Any of these things happen, and you're farked on the highway. Blowing out a hose is probably considered catastrophic, but is just as equally damning.

    Yeah, you could probably run for a long time and not have a problem with regular maintenance, but the inherent system safety just is not there, plain and simple. Think about how many times you have had a belt fail, versus how many times your steering tie-rod has broken on the open highway.

    Think about it, then either go hydro assist or don't drive next to me on-road.

    Also think about how much fun a return-to-center device would be when your engine dies in the center lane of the freeway.
     
  16. DEMON44

    DEMON44 Low-Tech Redneck

    Joined:
    Jan 8, 2003
    Posts:
    7,232
    Likes Received:
    15
    Location:
    Okotoks, Alberta
    maybe you don't realize, but any good orbital valve has a gerotor pump built into it. I'm 100% positive about that, I've rebuilt them before. that is why you can steer with a dead engine just like a armstrong steering a dead truck with mech linkage. I'm sure you can order an orbital without the gerotor pump cause I've seen them too.

    Very straight forward function, as you turn the steering wheel a wobble shaft in the bottom of the orbital turns the gerotor. so if your engine is dead and theres no fluid flow from the pump, your steering wheel and your arms are the prime mover and the orbital is the directional control valve AND the pump. work just fine.


    No don't get me wrong, I'm not supporting or condemning full hydraulic steering on the street. It just slays me that people that doen't really understand hydraulics are so afraid of it. its not unsafe.
     
  17. DEMON44

    DEMON44 Low-Tech Redneck

    Joined:
    Jan 8, 2003
    Posts:
    7,232
    Likes Received:
    15
    Location:
    Okotoks, Alberta

    just as an aside thats not how the system works. the pump never changes direction it always provides flow to the directional control valve. DCV just directs fluild flow to one side of the ram or the other. there is no lag fluid power transfer is instantaneous. being that fluids are virually incompressable and there is no air in the circuit. and fluid pressure is transfered at right angles to all surfaces equally while at a constant temperature.

    and the speed to power exerted ratio you have to taylor the size or the ram to the size of the pump for the intended useage. this is a dual acting single ended ram. (RAM assist)

    your pump displaces x.x GPM at xxxx RPM thats a constant linear relationship for a fixed displacement pump. the ram requires x GPM to extent at xx inchs/second and less GPM to retract at the same speed. because theres less surface area on the ram side when retracting. so a bigger ram reacts more slowly but with more power. a smaller ram reacts more quickly but with less power. but both extend and retract a different speeds at a given flow rate.

    SO a single sided dual acting ram doesn't extend and retract at the same speed at a given GPM. Now this is getting sort of scattered sorry. theres just so much basic information to hydraulics that I just can't explain on a key board.
     
  18. ntsqd

    ntsqd 1/2 ton status

    Joined:
    Nov 28, 2002
    Posts:
    3,381
    Likes Received:
    0
    Location:
    So. CA
    For one, I'm aware of that. Should you have the engine die then it's the same as if you had normal PS with a dead engine, & probably about the same amount of work to steer it.

    I do understand 95+% of how it works and I see too many easy failure modes that can go w/ no warning. In a mechanical linkage there are also failure modes. However, we've had nearly 100 years to work the bugs out of those parts and the failures are both predictable and only rarely do not give warning of impending doom. Hyd steering can't claim anything close to that.
    So I won't rule it out in the future, but I'd rule it out for now.
     
  19. yellowK20

    yellowK20 Well Lubricated Premium Member GMOTM Winner

    Joined:
    Dec 26, 2002
    Posts:
    7,603
    Likes Received:
    556
    Location:
    Wasilla AK,
    I'm with demon44 it's not unsafe when done properly . as for the 100 yers of mech steering ??? well they've been doing hydro steering on trucks and equipment for at least 60 years. the failure rate on both systems has to be about equal .

    A hydro hose is not going to fail completely and instantaneously if it ruptures you'd most likely have time to get the vehicle safely out of harms way. unless for some reason the fitting was broke off and all flow was lost


    Consider also the large tires I'd feel much safer runnig those 44" plus tires on full hydro steering than a crossover steering that still use stock rodends
     
  20. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

    Joined:
    May 19, 2001
    Posts:
    45,031
    Likes Received:
    366
    Location:
    Vancouver, WA, USA
    depends on the parts used. Full hydro from a high quality manufacture is plenty safe IMO. Station, Howe etc are more than up to the challenge.

    j
     

Share This Page