Erratic Hydraulics

[Gary Sweat]

Ideally it would go between the pump and main relief valve. From a practical standpoint it would probably be easier to install it before the inlet to the loader control valve. No matter where it is installed, you just need to consider which components are isolated by the test and which are not.

If I put it in the main feed line it's going to show flow all the time as the system is an open center so oil flows whether I'm using the loader or not. I'm trying to find out why the loader and bucket does not increase speed when I double the rpm on the pump.

It has been suggested that I might have leakage somewhere and it's possibly bleeding off the excess oil flow. I would like to put it somewhere that I can see if oil is flowing where it shouldn't be or if there is a restriction somewhere limiting the oil flow.

I had a concern about the tank port return line back to the transmission possibly restricting oil flow but I am not sure how I could determine this or if this would actually cause my problem. I don't think it is since the bucket will dump very quickly and the loader will drop quickly if I let it. It just always seems to stay the same speed going up no matter what rpm the engine is at.

 

[Jbrink64]

If I put it in the main feed line it's going to show flow all the time as the system is an open center so oil flows whether I'm using the loader or not. I'm trying to find out why the loader and bucket does not increase speed when I double the rpm on the pump.

Putting the flow meter here will verify all is well with the pump.

It has been suggested that I might have leakage somewhere and it's possibly bleeding off the excess oil flow. I would like to put it somewhere that I can see if oil is flowing where it shouldn't be or if there is a restriction somewhere limiting the oil flow.

An internal leakage would be at a set amount, therefore, increasing pump output would still increase the speed.

I had a concern about the tank port return line back to the transmission possibly restricting oil flow but I am not sure how I could determine this or if this would actually cause my problem. I don't think it is since the bucket will dump very quickly and the loader will drop quickly if I let it. It just always seems to stay the same speed going up no matter what rpm the engine is at.

Return line restriction would cause the pump to be under pressure when the control valves were in neutral. The pressure would increase as pump flow increased.

I would get a stopwatch and time the functions at idle, then at full throttle. I actually wear a chronograph for this very reason.

 

[J_J]

Have you checked for restricted orifice on output ports as I suggested.

What happens when you use the 3pt and the FEL at the same time. You are pressurizing the total hyd circuit when you do this. If you have a heavy load on the 3pt, and lift, what happens?

 

[Gary Sweat]

Return line restriction would cause the pump to be under pressure when the control valves were in neutral. The pressure would increase as pump flow increased.

I would get a stopwatch and time the functions at idle, then at full throttle. I actually wear a chronograph for this very reason.

The loader valve has a PB port that goes back to the 3pt and the return line is separate from that line. The return line only flows oil when the loader valve is operated. Otherwise it has no oil flowing in it. I had to make an adapter to use my oil fill hole for the return line.

 

[Gary Sweat]

Have you checked for restricted orifice on output ports as I suggested.

What happens when you use the 3pt and the FEL at the same time. You are pressurizing the total hyd circuit when you do this. If you have a heavy load on the 3pt, and lift, what happens?

JJ, I put all of the lines, valve and cylinders on new. None had any restrictor's installed and all cylinders are SAE6 ports. Valve work ports are SAE8 and in/out ports are SAE10. The loader moves reasonably well for a 4gpm pump but it doesn't increase speed between 1000rpm and 2000rpm. That's the part that has me confused. I would think it should speed up if even a little.

I can use the 3pt and loader only if I barely open the loader valve and then both move slow. Either one by itself will move quicker. You had told me a while back that my pump couldn't support both.

I can pick up the 5' bush hog and use the loader together but they will both go up very slowly. By themselves, neither one has a problem lifting a load. The 3pt also does not seem to go up any faster if I increase rpm but then maybe its not supposed to??

 

[J_J]

If you install a flow control gage in line, then you will see how many GPM's are flowing at any rpm.

The reason I mentioned the restricted fittings, was that one of the members purchased a fitting for the hyd, and one of the fittings was restricted. It was not what he wanted.

 

[AKKAMAAN]

The return line only flows oil when the loader valve is operated. Otherwise it has no oil flowing in it.

Did I read this right???

IF there is more than one return line, I think we have isolated your problem.

That return line to tank MUST ALWAYS flow oil in your system when valves are in neutral. If this return is the ONLY one, it must flow return oil ALL the time, even when operating. That is part of the "deal"with power beyond. If not, you valves are not plumbed in a true PB series.

I think you need to get a complete hydraulic schematic over YOUR original tractor system. Then we can see how your plumbing fits into that.

Comment about flow meters. If you try to use a flow meter with a restriction valve built in, consult with a pro, to avoid serious accidents. If it has no restriction valve, or if restriction is safely disabled, it is safe to use, because it will not build pressure.

See Bill's video...

 

[J_J]

If the valve is using PB port for normal flow, then he would only have fluid in the return port when using the cyl.

A gear pump will pump continuously, and the fluid has to flow through something.

Picture of the valve and the hoses marked as to where they are connected would be useful.

 

[Gary Sweat]

If the valve is using PB port for normal flow, then he would only have fluid in the return port when using the cyl.

A gear pump will pump continuously, and the fluid has to flow through something.

Picture of the valve and the hoses marked as to where they are connected would be useful.

Here are the photos of the valve plumbing.

 

[wdchyd]

Gary,

Just trying to catchup on this thread....Read it a couple of times and confused.......What is the original problem?..

Is it the dump cyls overrunning the pump gpm's?....