Loader Getting Weak With Use?

[Henro]

Bottom line is the loader and backhoe suck hind teat on the priority flow divider. At idle speed there is not enough flow to satisfy much more than the PS which is sucking on the front teat.

NOTE: Colorful language used for the entertainment of @hagrid The Lurker

Dan

I had always assumed, but never looked into it, that the priority float divider would only suck some milk when the steering was being activated.

My assumption was that when the priority flow divider wasn’t drinking, it sent all the milk on to its siblings for them to consume if they wanted.

So I figured if the OP was not turning the steering wheel, then whatever milk was in the system would be available at another teat…

Now I’m questioning myself. Does the priority float divider drink even when it’s not thirsty?

 

[TheOldHokie]

I had always assumed, but never looked into it, that the priority float divider would only suck some milk when the steering was being activated.

My assumption was that when the priority flow divider wasn’t drinking, it sent all the milk on to its siblings for them to consume if they wanted.

So I figured if the OP was not turning the steering wheel, then whatever milk was in the system would be available at another teat…

Now I’m questioning myself. Does the priority float divider drink even when it’s not thirsty?

Its an open center hydraulic system with fixed displacement pump.

The priority circuit gets a fixed flow regardless of steering activity. Anything if any left after that goes to the excess flow port. The flow is pressure compensated such that the priority flow does not change with differences in pressure between the two outlets.

In most of theses devices metering is not super precise and when inlet flow approachs the priority level the pressure balancing act gets iffy. The WSM specifys 2.1 GPM or more for priority flow so my calcs were best case.

Dan

 

[Henro]

Its sn open center hydraulic system.

The priority circuit gets a fixed flow regardless of steering actuvity. Anything if any left after that goes to the excess flow port. The flow is pressure compensated such that the priority flow does not change with differences in pressure between the two outlets.

In most of theses devices metering is not super precise and when inlet flow approachs the priority level the pressure balancing act gets iffy. The WSM specifys 2.1 GPM or more for priority flow so my calcs were best case.

Dan

So if the steering is not activated, then the amount of flow that the priority flow circuit demand is simply returned to the tank and not used for anything?

That possibility didn’t occur to me because it seemed like an inefficient use of the hydraulic pump output. Although it does seem that while the tractor is being used the steering IS frequently being activated.

 

[TheOldHokie]

So if the steering is not activated, then the amount of flow that the priority flow circuit demand is simply returned to the tank and not used for anything?

That possibility didn’t occur to me because it seemed like an inefficient use of the hydraulic pump output. Although it does seem that while the tractor is being used the steering IS frequently being activated.

Open center systems are inefficient by nature.

In the case of the BX23S the tank return on the PS valve is also used as a charge pump for the HST.

Now consider my L3901. It has a tandem hydraulic pump and no flow divider. The larger pump supplies the implement circuit and the smaller supplies the PS circuit. The PS circuit also acts as the charge pump for tje HST.

On some models Kubota also uses the PS circuit as a supply for the PTO and transmission clutchs.

But in ALL of these cases the pumps are positive displacement and the oil supply mainly circulates in an idle loop doing nothing but consume fuel, generate heat, and steal engine power.

Dan

 

[ruger1980]

So if the steering is not activated, then the amount of flow that the priority flow circuit demand is simply returned to the tank and not used for anything?

That possibility didn’t occur to me because it seemed like an inefficient use of the hydraulic pump output. Although it does seem that while the tractor is being used the steering IS frequently being activated.

No the oil that leaves the steering controller then supplies the PTO clutch and serves as charge oil for the HST. They need these 3 items to have prioritized flow over the implement functions.

 

[Soopitup]

Pulled the pressure relief valve today.
I found a few pieces of silicone in the spring. Nothing on the seat or in the valve itself.
Probably means there's more in the transmission.....

I also wanted to bump the pressure roughly 200 PSI (hot was 1700 PSI).
So I needed a .5mm shim (.1mm is 40 PSI).
The only thing I had handy was a stainless washer that was 1.39mm thick.
Fortunately the only shim in the valve was .83mm, so I swapped shims (.56mm).

Cold idle pressure bumped to 1700 PSI, cold max pressure bumped to 2100 PSI.
After running the tractor I only had a chance to check hot idle pressure (I don't think it was as hot as the last time I checked), it bumped to 1100 PSI.

 

[DustyRusty]

Shim Part 0.1 = 31351-37970 $0.71
.................... 0.2 = 31351-37960 $0.71
.................... 0.4 = 31351-37950 $0.71

Also don't forget to pick up a spare O ring.

 

[Soopitup]

Shim Part 0.1 = 31351-37970 $0.71
.................... 0.2 = 31351-37960 $0.71
.................... 0.4 = 31351-37950 $0.71

Also don't forget to pick up a spare O ring.

Thanks Paul!
I do need to start a spare parts stash for this thing.

 

[DustyRusty]

Thanks Paul!
I do need to start a spare parts stash for this thing.

I have a cork board that I keep all the small parts held up by push pins. Easy to find what I need in a hurry. It is the larger parts that seem to get scattered and I can't find when I need one, such as my hydraulic pressure tester. I just built another with the hope that the original one will surface. When my wife comes home she will ask what I did that day. If I say that I was working in the garage, she asks "What did you lose this time?".

 

[ruger1980]

Pulled the pressure relief valve today.
I found a few pieces of silicone in the spring. Nothing on the seat or in the valve itself.
Probably means there's more in the transmission.....

I also wanted to bump the pressure roughly 200 PSI (hot was 1700 PSI).
So I needed a .5mm shim (.1mm is 40 PSI).
The only thing I had handy was a stainless washer that was 1.39mm thick.
Fortunately the only shim in the valve was .83mm, so I swapped shims (.56mm).

Cold idle pressure bumped to 1700 PSI, cold max pressure bumped to 2100 PSI.
After running the tractor I only had a chance to check hot idle pressure (I don't think it was as hot as the last time I checked), it bumped to 1100 PSI.

Did you pull the poppet out of the seat and inspect it as well? At 2100psi you are well above the upper limit, but test it at operating temp to see how much it drops.

 

[Soopitup]

Did you pull the poppet out of the seat and inspect it as well? At 2100psi you are well above the upper limit, but test it at operating temp to see how much it drops.

The spring in the picture is "pointing" to the poppet.
I made sure the seat wasn't damaged, and shined a light with a mirror into the hole to make sure I didn't see anything.

Cold pressure is higher. Hot pressure was only 1700 PSI, so bumping it 200 PSI isn't much.
Hot pressure is 1900 PSI, just barely above spec.

I ran the loader for 3 hours today. Gave it good workout. Turned/moved a compost pile almost as big as the tractor, then used the stump bucket to dig a bunch of small roots and a couple of really big ones. It tore up the large roots better than I expected.
Hot idle pressure was even lower, 500 PSI. Not really a surprise, the fluid was hotter than the other day.
At least max pressure was up some. 1900 PSI.

 

[Soopitup]

Its an open center hydraulic system with fixed displacement pump.

The priority circuit gets a fixed flow regardless of steering activity. Anything if any left after that goes to the excess flow port. The flow is pressure compensated such that the priority flow does not change with differences in pressure between the two outlets.

In most of theses devices metering is not super precise and when inlet flow approachs the priority level the pressure balancing act gets iffy. The WSM specifys 2.1 GPM or more for priority flow so my calcs were best case.

Dan

I wanted to thank you for your insight Dan, I appreciate it.

I'll keep slowly picking at this as I can.

 

[DustyRusty]

Your oil-filled gauge is low on oil. That might be the reason for the low readings. Does your gauge have a dipstick and what type of oil does it take? Synthetic or dino? Your skinny dipstick might be too short, so it will only be halfway in when you check it. https://www.orangetractortalks.com/forums/threads/daily-chuckle.19013/page-738#post-712718

 

[ruger1980]

The spring in the picture is "pointing" to the poppet.
I made sure the seat wasn't damaged, and shined a light with a mirror into the hole to make sure I didn't see anything.

Cold pressure is higher. Hot pressure was only 1700 PSI, so bumping it 200 PSI isn't much.
Hot pressure is 1900 PSI, just barely above spec.

I ran the loader for 3 hours today. Gave it good workout. Turned/moved a compost pile almost as big as the tractor, then used the stump bucket to dig a bunch of small roots and a couple of really big ones. It tore up the large roots better than I expected.
Hot idle pressure was even lower, 500 PSI. Not really a surprise, the fluid was hotter than the other day.
At least max pressure was up some. 1900 PSI.

The item in the image above the spring is the seat and poppet together. The poppet is inside and can be removed from the seat

 

[TheOldHokie]

Did you pull the poppet out of the seat and inspect it as well? At 2100psi you are well above the upper limit, but test it at operating temp to see how much it drops.

I wanted to thank you for your insight Dan, I appreciate it.

I'll keep slowly picking at this as I can.

The item in the image above the spring is the seat and poppet together. The poppet is inside and can be removed from the seat

View attachment 126388

And based on the way the pressure is behaving very possible there is still some leakage across that seat.

Dan

 

[Soopitup]

It's possible. Everything looked ok other than the rubber in the spring.
The sealant pieces I found in the pickup mesh when I did the 50 hour service were gray. This was black. I wonder if there's a damaged internal seal somewhere.

The item in the image above the spring is the seat and poppet together. The poppet is inside and can be removed from the seat

View attachment 126388

Yes, I took the poppet out and inspected inside.