TC 45 DA Problem

[jbcoggins]

I'm having a problem while mowing with a Woods RD7200. Not sure if it is the tractor or mower. After mowing for about an hour, pto will slow down to a stop under heavy load then pick back up under less load. If tractor cools down for several hours, will mow fine again for about another hour then the problem starts again. I have recently changed fluid and filters thinking that might help, but it didn't change anything. No unusual noises when it acts up.

 

[jinman]

It sounds like your PTO hydraulic valve is not fully engaging and your PTO clutch is slipping due to reduced hydraulic pressure. It could be from a bent lever not allowing full engagement or a problem with the valve. It's not a simple test, but the valve can be checked for proper pressure to the clutch without tearing anything down. If the pressure is okay, slippage when warm indicates worn out clutch discs.

 

[JC-jetro]

Jim,

Is there a pressure port/cap next to the solenoid that one can verify pressure with PTO not-engaged and then engaged to check against factory specs? is there a regulator block to establish pto hyd pressure? I would not run the tractor till the cause established. Slipping pto clutch will lead to pre-mature failure.

JC,

 

[jbcoggins]

Thanks for the advice. As soon as I have time I will check the pressure and go from there. Will post what I find then.

 

[jinman]

Jim,

Is there a pressure port/cap next to the solenoid that one can verify pressure with PTO not-engaged and then engaged to check against factory specs?

As I said, it's not that simple. I would not have said that if it were a simple hookup and check. There is no solenoid on a New Holland and the PTO valve is below the operator's platform. On the "DA" models, the hole in the operator's platform below the seat has been eliminated, so I'm not sure how you could get to the valve without raising the operator's platform. If he has the opening or cuts one in the platform so he can get to the valve, there is a 6mm hex head plug to remove and a pressure gage installed. The engaged pressure on a TC45DA should be 260 +- 15 psi (engine at 2600 rpm). However, the first thing the OP should do is inspect his lever to make sure it is engaging the PTO valve properly. He can inspect it to see if the lever looks bent or something is binding.

 

[JC-jetro]

Jim,


Got it. Same set up like what I got withe the exception of having solenoid and it is on the side of transmission and very easy to have access too. As you said there is a good chance the lever is binding , bent or something that does not allow the valve to fully open. The question is we're talking pressure, even valve open at 25% should put the same 260+ with a slightly longer lag time, right? is the pto and power steering on the same circuit? can the pressure regulator malfunctioning causing less pressure when the valve is fully open?

JC,

 

[jinman]

The question is we're talking pressure, even valve open at 25% should put the same 260+ with a slightly longer lag time, right?

JC, your assumption is incorrect. The pressure relates to flow. The PTO system uses 0.8 gpm to operate. It's not a closed hydraulic system like a hydraulic cylinder. That allows you to feather the PTO with the lever and if you don't have the lever fully engaged so that full flow is supplied to the clutch, your clutch will slip. I've driven under bushes and had my lever moved partially toward OFF. The first indication of that is I can hear the rotary cutter slowing down. Moving the lever to fully engage (full flow with backpressure = 260 psi) will restore normal operation. It is just not a closed system where minimum flow can supply the correct pressure. As a matter of fact, there are two tubes on the bottom of the PTO valve that go to the clutch. If those tubes have defective o-ring seals, you'll never get full engagement either. There are many places for hydraulic leakage, but you have to start by checking the levers and then checking the pressure with a gage. If you try fixing this valve or adjusting pressure without knowing exactly what you are doing, it will likely blow out seals and you'll end up splitting your tractor and spending $$$. If you check the pressure and it's maybe 50-75 psi low, then you can make an adjustment to try and bring it within range. If that works, you've dodged a bullet. If it does not work, then your clutch seals are faulty and you need a teardown and repair. The biggest mistake you could make would be to adjust pressure to see if you could get the clutch to hold without knowing what the current pressure is. That's just asking for a pressure blowout.

 

[JC-jetro]

JC, your assumption is incorrect.

The biggest mistake you could make would be to adjust pressure to see if you could get the clutch to hold without knowing what the current pressure is. That's just asking for a pressure blowout.

Jim,

I understand exactly two points that you make. I was not suggesting to up the pressure to see if the pto holds. For sure the pressure should be read with the valve off and then on right at the pto piston using the port/plug intended for it. If that shows the main pressure does not meet the factory spec then you'll try to raise it at the source/regulator/relief. What it seems different with my rig is that my pto clutch piston is a closed circuit with on tube to provide hyd oil to the piston with an o-ring. If the piston seal should go bad then with solenoid open you constantly flowing hyd oil in the piston, leaking by oil and end up not achieving the pressure required. it is the same as a 3 point seal is leaking and can have the 3 point up as long as the engine is operating, once engine off and it drops quickly.


JC,

No mention of flow here, although I realize this not rig in question, concept is the same.

JC,

 

[JC-jetro]

Hmm, I see the tc45 is different with two tubes going to the clutch pack.

JC,

 

[jinman]

Hmm, I see the tc45 is different with two tubes going to the clutch pack.

JC,

Yes, one is the pressure tube and the other one is the lubrication tube. When the fluid exceeds the setting of the relief valve, it flows into the clutch as lubrication.