Hydrostatic Steering

[Mrwurm]

Recently, there was a thread about the difference between power steering and hydrostatic steering. My NH TC30 has no mechanical linkage between the steering wheel and the front wheels. Only two hoses and a cylinder provide the steering connection. This, I understand, fits the description of hydrostatic steering. That being said, here's my question.... With the engine switched off, I can turn the steering wheel (with some effort) and I am able to get a small steering response in the front wheels. This indicates to me that there is some 'pump' effect in the steering system. Would anyone care to explain how this works?

 

[TBone]

I think I was the one who started the thread about the diffences between the two systems. I understood the difference but didn't (and still don't) understand why the hydrostatic steering is supposed to be superior to power assisted steering.

In response to your question, I believe the limited movement you get is from residual pressure in your system. I get some of the same thing from my Bota as it is brand new.

I had an old International 444 whose hydraulics were completely shot. The pump provided enough pressure to steer it when the tractor was running but as soon as you shut it off the 3ph started falling and the steering was gone. You could spin the steering wheel like a top in both directions.

I have some land about 2 1/2 miles from my house and have to travel on a pretty busy highway to get to it. I always wondered what would happen if I suddenly lost hydraulic pressure on my old tractor. I know for a fact my steering would be rendered useless. Would I be able to safely stop it before I ran in a ditch or crossed the yellow line into oncoming traffic? Scary thought. And this is supposed to be better than power assisted steering? I don't think so.

Sorry for the rambling.

TBone

 

[BTI]

Kioti's are the same way if you turn the wheel with the tractor off the wheels still turn, the effort to do so must be increased but in a panic or emergency situation I think I could find PLENTY of strength to turn that wheel. /w3tcompact/icons/shocked.gif
BTI

 

[TBone]

It doesn't matter how strong you are, if you have hydrostatic steering the hydraulic pressure determines how much steering you have. There is no mechanical connection between the steering wheel and the wheels.

I suspect your tractor may have power assisted steering which can still be steered by brute force without the hydraulics' assistance.

TBone

 

[Soundguy]

Are there no systems that are hyd steering, that also have a manually actuated pump (by steerring wheel motion ), yet also have no drag link?

thought I had heard that this 'thing' existed.. but could be mistaken.

Soundguy

 

[Steve_in_Ont]

Jerry - You're correct that your NH TC tractor has what is generally refered to as "hydrostatic steering", and that it has no mechanical linkage from the steering wheel to the front tires. The reason why your tractor still has some steering when off is that the steering wheel is connected to a small rotor pump, that pushes oil into the steering system. For safety reasons, this pump also will act directly on the front axle when the power is off. However, you might of noticed, that steering with the power off takes considerable effort.

 

[TBone]

Soundguy I honestly don't know. The ones I have owned have not been set up that way. I would be interested to know if this "thing" did exist.

TBone

 

[TBone]

Well, you live and learn. It sounds like the newer tractors have a system that does allow you to "pump your own" hydraulic pressure in the event of power loss. Thanks for explaining that one.

TBone

 

[Mrwurm]

Sounds reassuring. /w3tcompact/icons/smile.gif

 

[Von]

Thats how the steering works in my Zamboni. The pump is right on the back of the steering wheel and has the lines going up front to a hydro. cyl. I can steer when the motor is off, but it is hard.

 

[Soundguy]

I believed that was how some of the tractor steering worked. Some of our heavy equipment is that way.

Soundguy

 

[Hoosier_Daddy]

My BX2200 explains the Steering as "Hydrostatic Type Power Steering" (kind of covers all the words being used in the discussion) and you can still turn the wheels with force.

But this discussion brings up a story about my gal on our old Simplicity (or as some call "simple city"). The nut holding the steering wheel kept working loose and although you could steer ok the steering wheel got pretty sloppy flopping around. Used locktight and everthing but just couldn't keep it tight. So, I drilled a horizontal hole through the steering wheel while it was tight against the shaft and put a small hardened bolt through and locked that baby down. Everything was cool until last fall when my gal was mowing down the side hill and the center nut popped off along with the threads and landed in her lap. I am not sure what the "pucker factor" was for her but I had to finish the mowing. Glad I put that horizontal bolt through there. She seems a little more relaxed with the new Bota but still won't mow the hill yet.

 

[hwp]

Kubota F series all have hydraulic steering - there is no mechanical linkage. The reason being that there is an engine and transmission in the between the steering box and the steer wheels at the rear. I suspect that many other rear wheel steer machines are the same.