Jump to content

IH hydro question


Gearclash
 Share

Recommended Posts

Help me out on a theory of operation question.  What exactly does the “clutch” (foot-n-inch?) pedal do on the  big frame hydro tractors?  Is it bad to use it a great deal in light load/low speed situations like running a mixer wagon along a feed bunk?  Thanks!

  • Like 1
Link to comment
Share on other sites

MUCH easier and smoother to use the hydro control for slowing down when needed. The foot and inch valve is only a hydraulic dump valve that dumps pressure

  • Like 1
Link to comment
Share on other sites

The foot-n-inch valve is a pilot valve that opens the main relief (drive pressure relief) valve.  

Does it hurt to use it a lot?  Well... over time I think it weakens the internal spring on the fni valve, ultimately causing low relief pressure. On a hydro, it really isn't necessary to do, but I totally understand why one would want to use it.  The clutch is so natural to use.  I have to get out of the clutch habit when I use the hydro tractors too.  Just try to get used to using the drive control lever instead.  Much smoother anyway.

So the answer to whether it hurts it any is.... "meh"... but it's probably better not to. It just wears out parts unnecessarily.

  • Like 2
Link to comment
Share on other sites

There was a fellow near us that bought a 656D hydro new with a loader. He could not get out of the habit of using the "clutch" and they did a lot of loader work. He would repeatedly step on the pedal, "shift" the SR lever to change directions/speed continually. The tractor was in the dealer a couple times a year for repair but he still liked it cause it shifted so easy. The only time i push the pedal on my 186 is to start the engine, don't even use it hitching to something.

  • Like 1
Link to comment
Share on other sites

I only step on the clutch in our 1066H in an emergency once every year or two average

  • Like 2
Link to comment
Share on other sites

7 minutes ago, J-Mech said:

The foot-n-inch valve is a pilot valve that opens the main relief (drive pressure relief) valve.  

Does it hurt to use it a lot?  Well... over time I think it can weaken the internal spring on the fni valve, ultimately causing low relief pressure. On a hydro, it really isn't necessary to do, but I totally understand why one would want to use it.  The clutch is so natural to use.  I have to get out of the clutch habit when I use the hydro tractors too.  Just try to get used to using the drive control lever instead.  

So the answer to whether it hurts it any is.... "meh"... but it's probably better not to. 

it is tough not to use that pedal. Loading round bales into feeders yesterday over the fence with my 656H. Easy to just inch close with fence with the pedal. Otherwise all hands are in use. I too always wondered if it hurt long term. Thanks J-Mech. Now I need therapy

  • Like 1
Link to comment
Share on other sites

17 minutes ago, Gearclash said:

Help me out on a theory of operation question.  What exactly does the “clutch” (foot-n-inch?) pedal do on the  big frame hydro tractors?  Is it bad to use it a great deal in light load/low speed situations like running a mixer wagon along a feed bunk?  Thanks!

It definitely was discouraged years ago. The clutch or foot an inch valve was a emergency stop type add on. Other machines don’t use them. The foot an inch is toed to relief valves blowing them off all the time is not recommended . Here are pics to see what happens valve is hooked to 8 when relief is opened applied it is tough on pistons, slipper shoes valve plates. Most all other applications do not use a foot a inch everything through drive control. Longevity is vastly improved.

6BA4A9A9-6A7E-4353-9F33-D3861D4E2EB0.png

E5DFCFC6-029D-4992-B7E8-12D9926289EE.png

996BAFB7-ABC3-4B6C-92B2-1F1EAE90905A.png

4A3FC1B6-2C3E-487F-8287-509513EF645A.png

  • Like 1
Link to comment
Share on other sites

The fni valve IS the valve where drive pressure is set, so when it gets weak, drive pressure is lost.  It contains the spring and shims that set drive pressure.  When you use it, you pull the spring stop away releasing spring tension, letting the tiny valve off its seat which dumps pressure off the back of the main forward and reverse valves opening them.  So, using it a lot works the spring. It's not a big spring.

Combine fni valves are the same set up. 

  • Like 1
Link to comment
Share on other sites

21 minutes ago, dale560 said:

The foot an inch is toed to relief valves blowing them off all the time is not recommended .

Kind of.  The fni valve is the pilot.  You aren't really "blowing off" the main relief valves.  They are large and move a lot of fluid, but their spring isn't very heavy.  Without the fni valve they wouldn't hold any pressure to even let the machine move.  They're a piloted valve. It doesn't hurt them at all to be open.  

Now, as far as load on the pistons and slippers... yes I can agree.  Dumping pressure while they are in stroke isn't necessarily easy on them.  Can it cause premature failure, I suppose it can. But if you were using the valve as you would a clutch it wouldn't be detrimental.  But if you "pop" it, yes.  Also, (*this is the big one*) if you use it at fast speeds (over let's say 6mph) then yes for sure.  Doing so bypasses the deceleration valve and the anticoast valves, which leaves all sorts of low pressures that have to build quickly when the pedal is released, all while the pump is in stroke.  Definitely a bad thing to use the fni at speeds above a "walk". 

  • Like 2
Link to comment
Share on other sites

I will also add that pulling the hydro control lever from high or full speed to neutral is as bad as using the fni valve at higher speeds (as I was saying above).  Again, doing so bypasses the deceleration and anticoast valves, leaving things in a dynamic state under no pressure.  It is equal to towing the hydro while it is in gear (on the hi/low transmission). You should always pull the lever back to just above neutral until the machine "engine brakes" to a crawl, then go into neutral.  Again, at speeds above a "walk". 

Link to comment
Share on other sites

49 minutes ago, cedar farm said:

it is tough not to use that pedal. Loading round bales into feeders yesterday over the fence with my 656H. Easy to just inch close with fence with the pedal. Otherwise all hands are in use. I too always wondered if it hurt long term. Thanks J-Mech. Now I need therapy

That is part of why I ask about using the FNI pedal.  Running the mixer wagon now I have a hand on the wheel all the time, and the other hand is running the mixer wagon controls.  Kinda wondering if I need to buy a third hand if I were to get a hydro for mixer wagon duty.  Having a dead man foot pedal to control the hydro would definitely have a place in this scenario.  

Edit to add.  

So the only time I would see using the FNI valve would be while unloading at the bunk.  The great majority of the time I unload in Lo 3 with my 856, at half engine speed give or take.  Not high speed at all.  The problem is some rations unload unevenly out of my mixer wagon so it take a lot of clutch dabbling to fill the bunk uniformly.  

Link to comment
Share on other sites

Got two Hydros as I said on here,but book says basically they were installed ONLY as a emergency stop for those farmers not accustomed yet to hand controls.

I NEVER uses mine intentionally,maybe hit it once a year going from a clutch tractor to a hydro and have a brain fart.Every time I cuss and say why did I do that. I find them ill equipped to be used in a situation where you need precision control of movement in either forward or reverse.

  • Like 1
Link to comment
Share on other sites

7 hours ago, Gearclash said:

That is part of why I ask about using the FNI pedal.  Running the mixer wagon now I have a hand on the wheel all the time, and the other hand is running the mixer wagon controls.  Kinda wondering if I need to buy a third hand if I were to get a hydro for mixer wagon duty.  Having a dead man foot pedal to control the hydro would definitely have a place in this scenario.  

Edit to add.  

So the only time I would see using the FNI valve would be while unloading at the bunk.  The great majority of the time I unload in Lo 3 with my 856, at half engine speed give or take.  Not high speed at all.  The problem is some rations unload unevenly out of my mixer wagon so it take a lot of clutch dabbling to fill the bunk uniformly.  

You buy one and that 856 will NEVER be on that mixer wagon again,guaranteed. 

  • Like 1
Link to comment
Share on other sites

Years ago in 1981, dads hired help blew the hydro pump up on his 815. They would mess around , step fni valve in and coast. If I remember right it trashed pistons and broke valve plate up. The local ihc shop rebuilt it then, there was no calling around to experts those old guys knew what they were doing and just fixed them in a day if I remember. Actually the guy that fixed it was shop foreman 24 or 5 years old but good at what he did. When talking about pilot relief operated all that means is fni valve controls the two relief valves in center section by tubing to outside and on tractors the hand control operates which range of speed pump and motor will be in. There is also another inherent relief valve in hydro systems, the spring ( 9) in cylinder block that provides tension to hold parts together to overcome 6,000 psi or more drive pressure. It is no 9 in picture. When you step on relief valve than reapply it at same control lever spot it loads the cylinder block, this spring gets a workout , you wash a little bit of oil by valve and bearing plates (2)starting wear lines , eventually screwing them up. The pistons are oil cavity connected and on other end the main wear part for pistons the brass slipper on awash plates absorb a huge force momentarily and it wears the heck out of them. The end piece of (4). Also a couple of old posts gives a little idea how they work. FYI if you ever want to check how spring that holds pump cyl together works on a combine yank hydro lever back to neutral at road speed. First you will raise back wheels abi then you will hear oil squeal and whoosh as plates separate ,dump oil. This is a extreme situation but it is about what can happen when fni valve is stepped and reapplied at full load.

68F2A096-CA0D-49B3-91DB-3CF995BEBA23.png

64715887-295A-4CF6-BC25-66BC877DF26F.png

08B2DA0B-3B3E-445D-841B-FA9007CF9294.png

  • Like 1
Link to comment
Share on other sites

The Foot-n-inch pedal is also has safety start feature to start the engine I figured between that and being a panic pedal for certain things that's why they were used only time I step on any of mine tractor or combine is to get things started 

  • Like 2
Link to comment
Share on other sites

8 hours ago, cedar farm said:

Probably why Deere combines don't use a FNI valve.

1983; went with my father to look at a used 6600 JD. It was stored in an old barn on a nearby farm. One of the dealer’s men was backing it out. Thing got stuck in reverse. The unloading auger caught the edge of the door. ?‍♂️The combine kept going and pulled the door down onto the top of the combine. Thought right away about the lack of a foot ’n inch pedal. Dad decided he wasn’t interested in buying ANY 6600 with a hydro. ?

  • Haha 1
Link to comment
Share on other sites

1 hour ago, Gearclash said:

Another question about the IH hydro.  I assume that the swash plates are servo controlled?  The actual effort of the S-R lever to control the swash plates is minimal?

Yes they are servo as are most hydro units except for small ones. Old swathers, older skid steer and stuff are mechanical control. That is what all the hubbub with f n r lever is on ihc tractors. They move into different zones that move motor and pump swash plates. Older combines usually just moved pump swash, but there are units that moved pump and motors. When it is all said and done the actual pumping part of even a modern hydro unit is the same as first ones designed long ago. Stuff like payloaders and newer new holland bidirectional tractors use a modern pump , fixed motor. Through electronics it gives you from 2 to 6 settings of swash plate. You then have handle control through the limit of selected setting. This makes it seem like you have a six speed transmission with only one hydro pump. New technology on old idea though. Versatile combines from 1969 would use a hydro pump as a motor ,through cable operation there was no transmission but pump and motor swash angles moving in tandem you had 0 to 12 mph with no gear transmission only a differential and drive axle. IHC tractors use two range speed like a gear drive, so all range of control in low is duplicated in high range.

Link to comment
Share on other sites

3 hours ago, dale560 said:

There is also another inherent relief valve in hydro systems, the spring ( 9) in cylinder block that provides tension to hold parts together to overcome 6,000 psi or more drive pressure. It is no 9 in picture.

That spring is in no way a relief valve, and it takes far more pressure to lift the block off the valve plate than 6000 PSI.  Assuming the hydrostat unit is in good working order, other parts would fail before that spring lifted the block.  You only have plate lift off if the valve plate and block are worn out. The function of the spring is to hold the block to the valve plate, not relieve pressure. Plate lift off is a bad thing that a worn out unit will experience. 

Link to comment
Share on other sites

15 minutes ago, J-Mech said:

That spring is in no way a relief valve, and it takes far more pressure to lift the block off the valve plate than 6000 PSI.  Assuming the hydrostat unit is in good working order, other parts would fail before that spring lifted the block.  You only have plate lift off if the valve plate and block are worn out. The function of the spring is to hold the block to the valve plate, not relieve pressure. Plate lift off is a bad thing that a worn out unit will experience. 

It is an inherent built in relief valve. It does not take much to blow the plates apart. Read the manuals ( described as valve plate off) when valve and bearing plate separate oil just dumps high pressure to case, and drain. This is why on stand alone units you have leaking cooler hoses gaskets and such, I have seen the bearing plate leak cause cracked cases.  Been working on these since I could crawl alongside dad, when dad didn’t want to spend any money he would fix his own. I did pick up a thing or 2 along the way.

  • Sad 1
Link to comment
Share on other sites

3 minutes ago, dale560 said:

It is an inherent built in relief valve. It does not take much to blow the plates apart. Read the manuals ( described as valve plate off) when valve and bearing plate separate oil just dumps high pressure to case, and drain. This is why on stand alone units you have leaking cooler hoses gaskets and such, I have seen the bearing plate leak cause cracked cases.  Been working on these since I could crawl alongside dad, when dad didn’t want to spend any money he would fix his own. I did pick up a thing or 2 along the way.

I hardly doubt separation between bearing plate and the block occurs unless like J-mech states its worn out or the block spring fails if high pressure from the pump pressurized the case on a combine for example it would blow the case drain hose because they are not high pressure hoses only held on with hose clamps 

  • Thanks 1
Link to comment
Share on other sites

5 minutes ago, dale560 said:

It is an inherent built in relief valve. It does not take much to blow the plates apart. Read the manuals ( described as valve plate off) when valve and bearing plate separate oil just dumps high pressure to case, and drain. This is why on stand alone units you have leaking cooler hoses gaskets and such, I have seen the bearing plate leak cause cracked cases.  Been working on these since I could crawl alongside dad, when dad didn’t want to spend any money he would fix his own. I did pick up a thing or 2 along the way.

You are incorrect.  I don't care how long you have been fooling with them.  The block spring is in no way a relief valve.  When plate lift off occurs, it is bad, and due to worn components.  What you are saying is equivalent to saying that a hydraulic hose can be considered a relief of sorts because if the system is over pressured it will burst.  I mean, you nailed the point for me when you talked about split cases because of plate lift off.  It is BAD.  The case isn't designed to relieve that much oil.  If lift off occurs, there is no direct path to tank large enough to carry off the oil.  

Link to comment
Share on other sites

The wear you quote  up with is .0005. Valve plate lift of and spring compression is a reality. Now to put this in easy to understand terms sudden pressure spikes will compress spring  separate valve and bearing plates. Oil leaks by microscopically scratching them, this leads to early failure, it also hammers the load bearing parts of hydro. So in answer to first question no it is not a good idea to use foot an inch for anything other than emergency. That results of what happen are clearly explained. Other mags used some other types of relief control also to keep the two main forward , reverse relief valve from opening and wearing. I will show you the other control reliefs one day. Again since I could crawl I watched as these things got worked on.

PS if you read your negative comments about valve plate and oil dump, in a ihc tractor it will just dump to trans case. On any other unit that is outside stand alone( again these units are identical to ihc tractor in operation other than pump motor control) when valve plate leak occurs it overflows radiator cooling port and will blow return pipe off when plates are trashed enough to stop working, again valve plate leakage to case(either motor or pump) case has a case drain return to cooler than sump. You need to study the manuals more. The spring separation if I have remembered right is about 8000 psi.

Link to comment
Share on other sites

The only way I could see that happening is if someone let the hydro coast down a steep grade and then released the pedal I seen that cause bearing plates to split out  the relief values will bypass oil at their rated pressure settings before any separation occurs on the block plate 

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...