Steering logic.

[Charlie_Iliff]

<font color="red"> ( You are right about the parallel, but if both are open center, the "open center" is the path of least resitance, then by plumbing in parallel it will actually flow to [and straight through] which ever one isn't being used. )

I agee. This is the point I was try to say with too many words perhaps. </font>

Another violent agreement on TBN reaches a stalemate. /forums/images/graemlins/smile.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/tongue.gif

 

[Spiffy]

J_J sounds like a pretty good plan, you'll need to post how it works. /forums/images/graemlins/cool.gif

The only thing I'm not quite sure I understand: whether the diverter you speak of is a "T" throttled on each side, one with a series of check valves, or one that has a solenoid (or perhaps mechanically actuated valve); oh, perhaps could be a pressure "sensing" demand actived valve. Maybe something competely different?

BTW J_J, thanks for passing on the the speed limiting device in another thread. So simple I'd never thought of it! /forums/images/graemlins/crazy.gif /forums/images/graemlins/grin.gif

 

[Spiffy]

<font color="blue"> Another violent agreement on TBN reaches a stalemate. </font> /forums/images/graemlins/grin.gif

Charlie, /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

Of course, I still haven't figured out whether the electrical guys think j j is imaginary or negative. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

Probably just because now I have one, but I'm really thinking PT is the most informative (very posible with PT's DIY sales and service) and fun forum on TBN. /forums/images/graemlins/cool.gif

 

[cqaigy]

<font color="red">Probably just because now I have one, but I'm really thinking PT is the most informative (very posible with PT's DIY sales and service) and fun forum on TBN. </font>

I TOTALY AGREE ALSO!!!! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

You guys really cracks me up. I don't spend as much time in the other area, but i really look forward to see what going on here at TBN

 

[Bob999]

J.J. said: <font color="red"> I only need to use a flow divider valve in place of the tee that I had mentioned earlier. This will isolate both circuits and provide fluid to both, steering and lift/tilt. </font>

I don't think the flow divider valves that I am familiar with will work any better than a "T" because they do flow division by varying the oriface size between the two branches. Varying oriface size does not provide isolation. Perhaps I am missing something and would appreciate understanding why a flow divider valve will work where a simple "T" won't.

 

[toy]

You are right it would be better to think of the steering valve as a pump. Now when someone mentioned that they had tried to steer the pt with the engine no running it would steer but was very hard would be easier if the machine was moving just like a car is easier to steer if moving than it would if setting still with the engine cut off. If the hose that came from the releif valve had a straight shot through the steering pump and over to the valve bank I don' beleive you would have any assistance with the steering, I beleive that in the steering pump there is a resistance [maybe a spring loaded spool ] I beleive it takes a certian amount of pressure to over come that spring and push the spool back which would let that oil go to the valve bank.but it only does this when there is enough pressure to push that spool back and all that will go the the valve bank is the amount of pressure over and above the amount that it takes to overcome that spring loaded spool. The real coarse threaded shaft that I mentioned is the mechanizmthat lets a little squirt in as the stering wheel is turned, there can be other mechanisms that would do the same. now as you turn the steering wheel it takes oil from the flow which lowers the pressure that would go to the valve bank when you turn it enough to lock the steering wheel and you are still trying to steer thenit is putting more pressue on the steering system unless it has a means for it to flow and that is where the internal port to let it go back to tank comes into play. If what ever they use in the steering valve to put a resistance to give the power assist to the steering would fail then you would loose the power assist. Like jj said you can block that port off then all the pressure would be on the steering valve unless you had a means to control that pressure and let any access go back to tank or to the valve bank. The steering pump is only putting out oil when you are turning the steering wheel so when you let off of trying to continue to steer the steering wheel then you get the pressure back I beleive. Now all that being said that is just my thoughts may not be right but it is still my thoughts. The thing I wonder didn't someone have to replace that steering pump recently. Haven't you took it apart yet to educate the rest of us? If you haven"t yet all I can say is hurry.

 

[toy]

I hope you can understand what I was trying to say in my last post but if not don't feel to bad it got me dizzy just trying to write it with all that oil going here and there. lol.

 

[toy]

A thought just came to me wouldn't it be nice to have someone on this forum that works in a hydraulic rebuild shop so the next time you go to one of these try your best to be a good salseman.

 

[BobRip]

I think we all are imaginary proportional to the time spent at tractorbynet/time spend on tractor by Power Trac.

Bob Rip
Electrical Engineer

 

[Sedgewood]

<font color="red"> The thing I wonder didn't someone have to replace that steering pump recently. Haven't you took it apart yet to educate the rest of us? If you haven"t yet all I can say is hurry. </font>

Do I need to 'fess up? /forums/images/graemlins/tongue.gif

I wrote the following on my website together with the attached picture of the disassembled unit {here}:

"6/8/05 I had been noticing for quite some time, a year or so, that sometimes when I turned the steering wheel slowly to make a course correction the steering input would have no effect - the steering wheel would turn but the tractor continued on its merry way. It wasn't too troublesome - a quick jerk of the wheel and it would catch and steer fine for that correction. Often it would work just fine. Then suddenly the other day it got much much worse."

"Without giving it a great deal of thought I assumed it was the steering valve that was amiss. I took the steering valve off and started disassembling it. BOING go the little springs."

"At this point I decided I needed expert help so I found the springs, got them back in place, and took the valve to the local hydraulics shop. This guy had never seen one of these before, took the cover off and BOING went the springs into his shop junk. While he was on the phone I found all the springs and ran. Even I can do BOING thank you very much."

"Back home, I did some detective work and between the markings on the unit and Google I managed to identify the unit as a Parker Ross Hydraguide HGF and found a service manual. We now have an inhouse expert - at chasing springs at least!"

"Further disassembly revealed a broken commutator seal. After much searching and talking to several distributors, the quickest source for a seal kit turns out to be Power-Trac, who stocks them, for a small fee Got the kit, got 'er all back together, installed."

"Grrrr.... still no steer. You boob, you didn't do your diagnostic work! So I get some JIC plugs and caps and isolate first one steering cylinder, then the other. It turns out the left cylinder is leaking internally past the piston. Another story for another day..."

Parker Ross Hydraguide HGF
Marked on housing: HGF 16126 064 01 J
Parker Hydraguide HGF steering valve seal kit part number = SK 000097
Power-Trac part number = M14934-1 - $73.65 on 6/3/05
Download a PDF version of Parker Service Manual from my site by clicking {here} to start a download or for a fresher copy, go to Parker's site {here} and download one by clicking on "Service Maintenance"

Sedgewood

 

[Spiffy]

I haven't downloaded the manuel yet, but your story may just prove invaluable someday. Thanks, Sedgewood!

Bob, by your definition, afraid "i" plead guilty. /forums/images/graemlins/blush.gif /forums/images/graemlins/grin.gif

If the hour meter lies along R and TBN along i; i'm afraid b>>a [a+bi], in regards to my PT anyway. Of course, all these TBN hours are probably saving many meter hours! /forums/images/graemlins/cool.gif Even if not, it's fun anyway... /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

 

[J_J]

Closed center valves are usually used with varaible displacement pumps, at neutral, there is no flow past the valve. The PT steering and lift pumps are fixed displacement pumps.

 

[J_J]

Check valves in the proper places after the flow divider would work.

 

[J_J]

This is a link to Eatons web site dealing with steering pumps. This is a good description of the system that I believe PT uses in our PT's

http://hydraulics.eaton.com/products/pdfs/C-STOV-MC001-E_part1.pdf



Maybe this will explain everything.

 

[Bob999]

J.J. said: <font color="red"> Check valves in the proper places after the flow divider would work.
</font>

I don't understand how a check valve would solve the problem. The check valve would presumably be installed to allow flow into the circuits--it would presumably prevent backflow. However, as I understand it, backflow is not the problem. Rather I understand the problem to be flow in the path of least resistance and a check valve installed as I understand it would be installed would not stop this flow.

 

[J_J]

Bob, forget the check valves. The flow divider will work to separate the circuit. In an equal flow divider, the amount of fluid through both should be equal to the pump output. The one side going to the steering would have a set amount of fluid governed by the pump output. It will be used by the steering , or go back to tank. The other side will go to lift and tilt, or go back to tank. Say the pump is 6 gpm. each side will get 3 gal of fluid to use or not. I should be able to operate steering at 3 gpm, and lift/tilt at 3 gpm.

I ran my 1445 for about 30 min testing the steering and lift circuits. No steering, full lift/tilt. In a large circle, little steering 50 % , I had average lift. In a very tight circle, 95 % steering, no lockout, lift was very slow. In full turn lockout, no lift.

I have a Davis trencher, that is articulated, and steers by a simple valve. Push left, it turns left. Push right, it turns right.

By the way, the lift and tilt circuits must be in parallel, since they can both operate at the same time. The three spool valve is open center, and fluid is always running through the valve, if the engine is running. Fluid also runs through the steering valve when engine is runing

 

[J_J]

On the matter of steering, does your steering wheel return to center if you let go .

 

[Bob999]

J.J. asked: <font color="red"> On the matter of steering, does your steering wheel return to center if you let go .
</font>

My 1845 does not.

 

[BobRip]

So let me get this straight in the present system you can get upto 10 gallons a minute to steer. With the diverter, you will now have 5 gallons going to each attachment. So when you are steering with this setup the most you will get is 5 gallons. So instead of the steering being slow when you are lifting or tilting it will be slow all of the time. OK /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif

Bob Rip

 

[J_J]

No. not really. A larger pump will more than make up the difference of any disparity. The 10 gpm was just a figure for explanation. The pump is actually a 1.5 to 3 gpm Barnes pump to supply the fluid for the steering and lift and tilt, so a 3 gpm to 6 gpm will work fine.

I am so very sorry that I offended your logic, but I have the utmost confidence in my ability to make it happen. So let it rest. OK.