Hydraulic pressure and RPM output/power

[CapeCodCubs]

Hi,

I am having a strange issue with getting the tractor to get full throttle. It is like hydraulic pressure is interfering. Last year I could not get this Cub to rev up, and discovered that the hydraulics settings control stops were restricting high rpms. So I set the control stop further back ( not up ). None of this makes sense to me. Today I was plowing and could not get the Cub to really rev up, it didn't really matter because the governor was working well and giving me all the power I needed to plow. What would be causing the hydraulic pressure to hold the rpms back. A buddy came over seemed to think it was a hydraulic relief valve or switch. The Cub is a 1976 late model. Moving the hydraulic lever makes it rev higher also.

Pretty baffled by this...thanks for any insight or thoughts and hope everyone is having a nice long weekend.

thanks....

[Jim Becker]

Since you have had something going on with the Touch-Control stops, start by adjusting them as explained in the Touch-Control Serviceman's Handbook (assuming you haven't already done so). If you still have a problem after that, start to look for other problems. The Serviceman's Handbook is in the PDF manuals. I think you will find the pocedure on the last page.

[CapeCodCubs]

Heading there now, thank you

[SamsFarm]

Sounds like for some odd reason the touch control has not completed its cycle in relation to the touch control operation lever!

[Boss Hog]

Pump may be dead heading , if you work the hydraulics up or down does the engine speed up? If so relief valve sticking

[CapeCodCubs]

Pump may be dead heading , if you work the hydraulics up or down does the engine speed up? If so relief valve sticking

Yes, that is what is happening. The relief valve is sticking. That is what my neighbor was saying, He said to ask the Cub group. What causes it to stick? What is the fix.

[CapeCodCubs]

Sounds like for some odd reason the touch control has not completed its cycle in relation to the touch control operation lever!

One of my neighbors who is not on groups like this and is a 5th generation dairy farmer said it is not cycling through. He also said he thought a relief valve was stuck.

[Jim Becker]

I'm more inclined to say the problem is the pressure regulator valve. It has an orifice and orifice screen as part of that valve's circuitry. You access them through a pipe plug in the head. Unscrew the plug, then unscrew the orifice and screen. There are previous posts on this, probably with pictures.

[SamsFarm]

Throw a pressure gauge (suitable for hydraulic pressure) on it.

If it is the relief valve, pressure would be higher than what the book calls out!

However the relief valve should only be operating when the rockshaft is doing its highest rated load.

If the hydraulics are not in work mode, then the oil should be in a constant low pressure loop from tank to pump back to the tank, then repeat, repeat repeat.

Is it doing this no matter where the rockshaft is positioned?

[CapeCodCubs]

Throw a pressure gauge (suitable for hydraulic pressure) on it. I plan on borrowing a pressure gauge, I might have one but who knows where?

If it is the relief valve, pressure would be higher than what the book calls out! I read the service book and will check to see if it exceeds 1100-1500 psi

However the relief valve should only be operating when the rockshaft is doing its highest rated load.

If the hydraulics are not in work mode, then the oil should be in a constant low pressure loop from tank to pump back to the tank, then repeat, repeat repeat. That is what my friend was saying but he said it was not cycling correctly like what you are saying

Is it doing this no matter where the rockshaft is positioned?

If I raise the rockshaft the engine races

Thanks guys, I am starting to understand this system. The service book was very helpful, it did not mention this situation in the trouble shooting section, but it helped explain the system itself and with what my friend mentioned and what you, David and Jim are saying this is becoming clearer. Now another neighbor is saying it is the relief valve. In the book I see mention of the pressure regulator valve as Jim said. I will look for posts on this. What is usually the problem? Does it get clogged? Or stuck...

Thanks for the great help so far, will report back later in the day...pushing 1 AM

[Jim Becker]

. . . Thanks guys, I am starting to understand this system. The service book was very helpful, it did not mention this situation in the trouble shooting section, . . .

Condition 4 in the Troubleshooting Chart. Probable cause is Number 1 in the Possible Causes, as I described in my second post.

Since you have a late tractor, the pipe plug probably requires an Allen type wrench.

[CapeCodCubs]

Looking at page 10 and I see it!

I am far better at growing stuff with my Cubs than understanding their issues.

Thank you so much for taking the time to help me