Hydraulics....

John M · Sep 16, 2013

Helping a friend here so bear with me.....

The guy has an M, with loader and 3pt. The loader operates off a PTO pump. One of the hoses was leaking, so he replaced it, BUT he couldn't find the 3/4" hose that was already on there, so he used 1/2", which he says was all he could find locally. Now the loader operates slower than what it did before. Solutoin: FInd 3/4" hose, or should the 1/2" work and hes done something wrong when reinstalling the new hose???

Second, the 3point: Running off of belly pump via a secondary valve. Hose from the pump to the valve, hose from valve to cylinder(s), one hose dead heads with a coupler for use on implement previous owner had. Now, the valve is what I call a 3 position, up, neutral, and down. BUT the 3pt raises in both up and down, and in neutral 3pt drops, faster with his mower on it, like dead drop. Is this problem in the valve? Ive suggested to him to just forget the valve and run straight off the belly pump.

Phil Tibbetts · Sep 16, 2013

If it needs a 3/4 hose a 1/2 inch will restrict the flow.

John G. Hasler · Sep 16, 2013

> Running off of belly pump via a secondary valve.
> Hose from the pump to the valve, hose from valve
> to cylinder(s), one hose dead heads with a
> coupler for use on implement previous owner had.
> Now, the valve is what I call a 3 position, up,
> neutral, and down.

No return line?

rustyfarmall · Sep 16, 2013

A 3/4 inch hose has TWICE the capacity of a 1/2 inch hose. That 1/2 inch hose he used as a replacement just ain"t gonna do the job. You will need to look for the 3/4 hose somewhere other than the local farm supply.

John M · Sep 16, 2013

Yes, forgot about that one! Goes back to the pump via the drain plug.

John G. Hasler · Sep 16, 2013

I think you've got the hoses scrambled.

John M · Sep 16, 2013

Thats what I was thinking, but evidently this worked for the previous owner, (now deceased). Im thinking something has gone bad in the valve itself, since both positions allow the 3pt to raise, which I dont think it should do. The way its plumbed, the 3 point should lift only when the handle is pulled back, Im just guessing, all Ive seen is pics of it. Im trying to get the pics up as I type.

John M · Sep 16, 2013

Valve. Back hose goes to 3pt, front hose dead heads.

notjustair · Sep 16, 2013

That's the way mine is set up, although mine is live hydraulics. That front hose needs a way to return to the sump if there is no implement on it. I have a T in mine that I open if it is not hooked to an implement - that T lets it return the fluid.

When you use the lever you get fluid no matter which way you push it. That's how a double acting cylinder has power up or down. When one side has fluid pressure the opposite side of the valve is open to let the fluid return as needed. You have to have a return to the pump on the "lowering" side (even if you aren't using it) or you are deadheading the pump every time you let the three point down. Regardless of whether you hook two hoses up to that tractor you need to plan on both sides of the vavke having pressure at all times. Get that fixed and then see what happens. Hydraulics are like wiring. If it isn't set up right you can't always predict what weird things will happen.

mkirsch · Sep 16, 2013

If the 3pt goes up with the valve either forward or back, and drops when the valve is in the center position, the valve is blown out internally. It's probably junk now.

Probably due to the deadheaded hose. There is no relief valve on that type of valve, and the one down in the belly pump is either insufficient or not working.

The pressure built up and the old o-rings couldn't take it.

If he wants one-way operation, he can just connect the cylinder directly to the belly pump outlet and use the lever on the side of the tractor. That is the cheapest fix.

John M · Sep 16, 2013

I understand what your saying, but my main concern on this is why no matter which way he moves the valve, the 3pt comes up. Ex: If he pulls it back, it should come up, in the middle it should stop and hold there, forward it would be down, NORMALLY and plumbed right. If he pulls it back, or pushes it forward, the 3pt comes up. In the middle the 3pt drops. Im waiting on him to send me more pics that should help clarify the 3pt problem. Im thinking that he has a problem in the valve itself causeing it to rise in both positions and just drop in the middle. Im alos trying to get him to forgetthis valve and use just the belly pump for the 3pt, since he says he doesnt use that valve for anything else but the 3point.

John M · Sep 16, 2013

Thats what Im thinking as well, and trying to get
him to plumb it to the belly pump.

D Slater · Sep 16, 2013

If the hose on left in picture is pressure from the pump? Right one return to reservoir? Top rear to lift cylinder? Top front hose blocked? Front hose blocked is the problem. It needs to dump back to reservoir or tee into the return line on the right of valve. When he moves the valve to lower he is dead heading the pressure and some is leaking by the spool when it does that and causing a pressure raise on the lift line and 3 point.

John G. Hasler · Sep 16, 2013

> The pressure built up and the old o-rings
> couldn't take it.

I don't claim to be an expert on hydraulics, but I've never seen a spool valve that relied on o-rings for anything but leakage control.

John M · Sep 16, 2013

Both you and notjustair say the same thing, so Ill have him try that if he wants to. For temparay measures, I assume it would be OK to just tee this line in and leave it?

John G. Hasler · Sep 16, 2013

> Thats what Im thinking as well, and trying to get
> him to plumb it to the belly pump.

That would be the simplest solution if all he needs is pressure for that single-acting 3-point cylinder.

D Slater · Sep 16, 2013

One advantage of the valve is lowering a heavy load on the 3 point. When hooked to a belley pump side port a heavy load will take a hard push on the rod to overcome the check valve. Hard to do sometimes without dropping all at once.
Disadvantage of the extra valve is any internal leakage in the valve between spool and bore will let the 3 point leak down. Plus extra plumbing.
If the liftall works as it should the check or poppet valve blocks leakage back to the reservoir. Still can have the lift cylinder leak of.
Unless the extra valve is in bad shape leak down shouldn't be bad with it.

John G. Hasler · Sep 16, 2013

Does the three-point come up at the same speed forward or back, or does it come up fast in one direction and slow in the other?

John M · Sep 16, 2013

He said it looks like the same to him.

John M · Sep 16, 2013

Thats he says in one of his problems, when he moves it lever to the center position, it drops all the way down, it wont hold anything up in that position, and says he cant control how far he needs to lift his cutter for like heavy spots. I havent heard back from him in the last little bit as to what hes going to do yet.

IH fan · Sep 16, 2013

(quoted from post at 13:47:30 09/16/13) Thats he says in one of his problems, when he moves it lever to the center position, it drops all the way down, it wont hold anything up in that position, and says he cant control how far he needs to lift his cutter for like heavy spots. I havent heard back from him in the last little bit as to what hes going to do yet.

If I understand these old H and M systems right, with an auxiliary valve, the main hydraulic lever needs to be locked back in place to supply the aux. valve. Then if it's working the way you say, there is something wrong inside the valve, because it appears to be plumbed correctly. The one port being deadheaded will not make any difference, it will just dump over the main relief valve when the valve is operated in that direction. The aux. valve does not need a separate relief valve. However, for the 3 point to remain stationary in the center (neutral) position, the spool configuration needs to have the work (A&B) ports blocked in neutral. If it worked before and not now, it had the right spool. I agree that something is either leaking badly or broken inside the valve. The pump/relief valve on these old systems should not be capable of "breaking" the cast body of the aux. valve as the valve should be good for 2000psi or better, but it still appears something is broken in there.

D Slater · Sep 16, 2013

I used a valve just like that one before on a M single acting cylinder loader to control drop. Just run a pressure line to inlet on the valve. Return line port to lift cylinder or cylinders.
Plugged one valve outlet and run a hose from the other outlet to the drain opening on the reservoir. Pull the liftall rod to raise, then move the valve lever one way for drop. If that valve won't work like that or the other way I mentioned, there's something wrong with it.

John G. Hasler · Sep 16, 2013

> When he moves the valve to lower he is dead
> heading the pressure and some is leaking by the
> spool when it does that and causing a pressure
> raise on the lift line and 3 point.

But when he does that he is also connecting the lift line to the return so the leakage should not be able to develop any pressure in the lift line: the leakage should just flow down the return.

John G. Hasler · Sep 16, 2013

> The pump/relief valve on these old systems
> should not be capable of "breaking" the cast
> body of the aux. valve as the valve should be
> good for 2000psi or better, but it still appears > something is broken in there.

I agree. A spool valve is just a steel rod with notches in it sliding in a steel block with holes in it.

Does that valve perhaps have a double-acting check valve in it? I can't think of any way to misconnect the system in such a way as to cause those symptoms.

Owen Aaland · Sep 16, 2013

(quoted from post at 13:09:26 09/16/13) If the 3pt goes up with the valve either forward or back, and drops when the valve is in the center position, the valve is blown out internally. It's probably junk now.

Probably due to the deadheaded hose. [b:57bdc9500c][u:57bdc9500c][i:57bdc9500c]There is no relief valve on that type of valve[/i:57bdc9500c][/u:57bdc9500c][/b:57bdc9500c], and the one down in the belly pump is either insufficient or not working.

The pressure built up and the old o-rings couldn't take it.

If he wants one-way operation, he can just connect the cylinder directly to the belly pump outlet and use the lever on the side of the tractor. That is the cheapest fix.

There is a relief valve in that control valve. It is located in the bore next to the spool that has the inverted hex plug next to the handle.

D Slater · Sep 16, 2013

You have a point on that.
Don't know what's going on, most of those valves relief setting is higher than the liftall develops also.
Have a two spool valve on a tractor now with one spool operating a double acting cylinder and the other a one port cylinder. Just have one outlet port plumbed to the reservoir for the spool operating a one way cylinder. When I lower with that valve the pressure to that port just flows to the reservoir and the lift port flows back into the return line as the lift cylinder retracts.

Owen Aaland · Sep 16, 2013

I've got a valve just like the one in the picture on my W9. I made sure the valve had a relief before I installed it.

gbs · Sep 16, 2013

look at the hole size inside the two different hose ends that will answer the question flow restriction

Hydraulics....

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