L4060 HSTC PTO takes a minute to disengage sometimes.

[GBJeffOH]

I have a 12' woods finish mower.

I always engage and disengage the PTO at idle.

If the mower keeps spinning and I put it is some tall grass it stops. If I wait a minute it stops. If I rev it and back to idle it stops.

It is not electrical because I can get of the seat and the tractor keeps running.

Maybe I should check the PTO operating pressure. When engaged it should be 363 to 413 PSI. When disengaged it should be 0 PSI.

The tractor has about 570 hours on it.

The Super UDT2 oil was changed 300 hours ago.

 

[kubotafreak]

Lower rpm before disengaging. Too high on the rpms accelerates the pto brake wear.

 

[GBJeffOH]

Lower rpm before disengaging. Too high on the rpms accelerates the pto brake wear.

I always engage and disengage the PTO at idle except one time to see what would happen.

 

[GBJeffOH]

I have a 12' woods finish mower.

I always engage and disengage the PTO at idle.

If the mower keeps spinning and I put it is some tall grass it stops. If I wait a minute it stops. If I rev it and back to idle it stops.

It is not electrical because I can get of the seat and the tractor keeps running.

Maybe I should check the PTO operating pressure. When engaged it should be 363 to 413 PSI. When disengaged it should be 0 PSI.

The tractor has about 570 hours on it.

The Super UDT2 oil was changed 300 hours ago.

I got the Gauge hooked up. I went out and did some mowing. It started out at 250 PSI, after about 30 minutes it was 320 PSI. After about 45 minutes the gauge was pointing straight down. I thought the brand new gauge broke. It goes to 600 PSI so I think it was about 800 PSI.

The PTO did not shut off. The engine was at idle. I engaged the pto again and drove over to some high grass. I went back to idle and drove into the high grass. It shut off and the gauge went back to 0.

I ran the mower another 15 minutes and the gauge stayed at 320 PSI.

 

[TheOldHokie]

I got the Gauge hooked up. I went out and did some mowing. It started out at 250 PSI, after about 30 minutes it was 320 PSI. After about 45 minutes the gauge was pointing straight down. I thought the brand new gauge broke. It goes to 600 PSI so I think it was about 800 PSI.

The PTO did not shut off. The engine was at idle. I engaged the pto again and drove over to some high grass. I went back to idle and drove into the high grass. It shut off and the gauge went back to 0.

I ran the mower another 15 minutes and the gauge stayed at 320 PSI.

I am having a little trouble following that descrption but if I got it right the pressure is "normal" then goes way high then to zero. If that's right sounds like it might be a malfunctioning relief valve.

Dan

 

[GBJeffOH]

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I am having a little trouble following that chronology but if I got it right the pressure is "normal" then goes way high then to zero. If that's right sounds like it might be a malfunctioning relief valve.

Dan

It is low for a while. Then a little low. Then way high. It goes to zero when I shut off the PTO.

 

[TheOldHokie]

It is low for a while. Then a little low. Then way high. It goes to zero when I shut off the PTO.

I have to confess I have not read the WSM. Isn't it supposed to go to zero when you shut off the PTO?

Dan

 

[GBJeffOH]

I have a 12' woods finish mower.

I always engage and disengage the PTO at idle.

If the mower keeps spinning and I put it is some tall grass it stops. If I wait a minute it stops. If I rev it and back to idle it stops.

It is not electrical because I can get of the seat and the tractor keeps running.

Maybe I should check the PTO operating pressure. When engaged it should be 363 to 413 PSI. When disengaged it should be 0 PSI.

The tractor has about 570 hours on it.

The Super UDT2 oil was changed 300 hours ago.

This is the Regulator.

 

[GBJeffOH]

This is the Regulator.
View attachment 108533

I have to pull the third function and the RH tank to get to it.

#120 goes to a sensor like the sensor on the HST petal. I don't know what that is for.

 

[TheOldHokie]

I have to pull the third function and the RH tank to get to it.

#120 goes to a sensor like the sensor on the HST petal. I don't know what that is for.

Surely the WSM describes the operation and gives you test and trouble shooting guidance.

Looking at the parts diagram there is plenty of electrical involvement. Checking those sensors would seem to be a good use of time.

Dan

 

[GBJeffOH]

I have a 12' woods finish mower.

I always engage and disengage the PTO at idle.

If the mower keeps spinning and I put it is some tall grass it stops. If I wait a minute it stops. If I rev it and back to idle it stops.

It is not electrical because I can get of the seat and the tractor keeps running.

Maybe I should check the PTO operating pressure. When engaged it should be 363 to 413 PSI. When disengaged it should be 0 PSI.

The tractor has about 570 hours on it.

The Super UDT2 oil was changed 300 hours ago.

I hooked up the brush hog.
At .4 hours it was 340 PSI, .6 hours 600 PSI.
I idled it and shut off the PTO. I shut off as it should.
At .7 hours it was 800 PSI. I idled it and shut off the PTO. The light on the dash shut off. The PTO did not. I engaged the PTO and let idle for a minute. It went down to 600 PSI and it shut off as it should.

 

[GBJeffOH]

I have a 12' woods finish mower.

I always engage and disengage the PTO at idle.

If the mower keeps spinning and I put it is some tall grass it stops. If I wait a minute it stops. If I rev it and back to idle it stops.

It is not electrical because I can get of the seat and the tractor keeps running.

Maybe I should check the PTO operating pressure. When engaged it should be 363 to 413 PSI. When disengaged it should be 0 PSI.

The tractor has about 570 hours on it.

The Super UDT2 oil was changed 300 hours ago.

I got this from Messick's
Issue:

On some HST models, the PTO will remain running after turning off the switch after the machine gets to operating temperature. When Pressure testing the system, dealers will see PTO clutch pressures well above the specified amount (600-800 psi).

Solution

Solution:

When experiencing this issue, remove the check ball and valve from the PTO clutch inlet elbow. See attached document for more information.


I have not done that yet. I would bet that will fix it.

 

[Henro]

I’m having trouble seeing how removing something that was part of the original design by the manufacture, would be called a fix. Seems more like it would be a workaround.

So was this something that Kubota recommended be done? Did Kubota issue a service bulletin advising to do this? If it were my tractor, I would probably try this. But I’d also like to know where the idea came from…

 

[GBJeffOH]

Surely the WSM describes the operation and gives you test and trouble shooting guidance.

Looking at the parts diagram there is plenty of electrical involvement. Checking those sensors would seem to be a good use of time.

Dan

The WSM does not mention high pressure.

The only electric is 1 wire to turn on the solenoid.

The rest is HST stuff.

 

[GBJeffOH]

I’m having trouble seeing how removing something that was part of the original design by the manufacture, would be called a fix. Seems more like it would be a workaround.

So was this something that Kubota recommended be done? Did Kubota issue a service bulletin advising to do this? If it were my tractor, I would probably try this. But I’d also like to know where the idea came from…

Messick's said it is a Kubota knowledge article.

 

[GBJeffOH]

I have to confess I have not read the WSM. Isn't it supposed to go to zero when you shut off the PTO?

Dan

It goes to Zero in about 1 second. If the pressure is not way high. About 800PSI.

 

[GBJeffOH]

I got this from Messick's
Issue:

On some HST models, the PTO will remain running after turning off the switch after the machine gets to operating temperature. When Pressure testing the system, dealers will see PTO clutch pressures well above the specified amount (600-800 psi).

Solution

Solution:

When experiencing this issue, remove the check ball and valve from the PTO clutch inlet elbow. See attached document for more information.


I have not done that yet. I would bet that will fix it.

Before I took out the check valve.
At .4 hours the pressure was 340 PSI.

At .6 hours the pressure was 600 PSI.
The PTO would still shut off.

At .7 hours the pressure was around 800 PSI.
The PTO would not shut off. You can even shut off the engine and start and the PTO is engaged.
Wait about 45 seconds and the pressure drops and it is normal for about 5 minutes.

After I took out the check valve.
At .3 hours the pressure was 280 PSI.

At .6 hours the pressure was 380 PSI.

At 1.4 hours the pressure was 380 PSI.

I think the problem is fixed.

 

[GBJeffOH]

I have a 12' woods finish mower.

I always engage and disengage the PTO at idle.

If the mower keeps spinning and I put it is some tall grass it stops. If I wait a minute it stops. If I rev it and back to idle it stops.

It is not electrical because I can get of the seat and the tractor keeps running.

Maybe I should check the PTO operating pressure. When engaged it should be 363 to 413 PSI. When disengaged it should be 0 PSI.

The tractor has about 570 hours on it.

The Super UDT2 oil was changed 300 hours ago.

This is where the check valve is.