HELP!!! L4400HST PTO Clutch

   / HELP!!! L4400HST PTO Clutch #1  

tallyho8

Elite Member
Joined
Aug 1, 2004
Messages
4,998
Location
Who Dat Nation west of Westwego east of Ama south
Tractor
Kubota L4400, Kubota ZD326
I bought an L4400HST 24 months ago and think I have a PTO clutch problem. I push in my clutch pedal, put the PTO in gear, slowly let up on the clutch pedal and then raise the throttle. The 6' bush hog starts turning fast and will cut light grass.

When I go into thick grass, the driveshaft to the bush hog stops turning. I am thinking that the PTO clutch is worn out but can't believe that it could have happened so soon with so little light use. I always baby the clutch when engaging and disengaging the PTO and have done very little bush hogging with this tractor.

I only have 150 hours on it and maybe 40 of these are cutting grass. Mostly it is using the box blade, disc or front end loader. My last 2 tractors cut my heavy grass for over 10 years each without ever changing a clutch and the last one was just an 18hp Yanmar. No one has ever driven it but me and I baby my equipment.

Even though it is still under warranty, there is no warranty at all on a clutch disc and it must be very expensive to replace.

1. Is this a worn out PTO clutch or could it be something else?

2. If it is a worn out clutch, what could have made this new Kubota wear out a clutch so quick?
 
   / HELP!!! L4400HST PTO Clutch #2  
Why do you think it is the clutch? Wouldn't a bad clutch prevent you from engaging the PTO? It sounds like you are engaging the PTO without problem. Did I miss something?

It sounds more like a hydraulic issue rather than a clutch issue.
 
   / HELP!!! L4400HST PTO Clutch #3  
I would check the clutch engagement lever that the cable operates. Do you have a parts manual for your machine? If not pm me.
 
   / HELP!!! L4400HST PTO Clutch #4  
I would check the fluid level just to be on the safe side. It sounds like the shear pin or bolt has sheared. If the Rotary Cutter has a slip disc clutch this may be too loose. My money is on the shear pin or slip clutch on the Rotary Cutter.
 
   / HELP!!! L4400HST PTO Clutch
  • Thread Starter
#5  
Why do you think it is the clutch? Wouldn't a bad clutch prevent you from engaging the PTO?

I am not familiar with what kind of PTO clutch is in this Kubota. I know that a worn standard transmission clutch disc in a car or tractor will slip when it is under a load and I don't know if this PTO clutch operates under the same principle. Also, there may be a built-in slip clutch that is slipping too easily.

I would check the clutch engagement lever that the cable operates. Do you have a parts manual for your machine? If not pm me.

I checked and the cable is pulling the lever all the way up to the stop where it can't go any further.
 
   / HELP!!! L4400HST PTO Clutch
  • Thread Starter
#6  
I would check the fluid level just to be on the safe side. It sounds like the shear pin or bolt has sheared. If the Rotary Cutter has a slip disc clutch this may be too loose. My money is on the shear pin or slip clutch on the Rotary Cutter.

The fluid is full and the filter only has 94 hours on it.

The PTO shaft coming out of the rear of the tractor that connects to the PTO driveshaft going to the bush hog stops turning so it would not be a shear pin or slip clutch on the cutter.
 
   / HELP!!! L4400HST PTO Clutch #7  
What RPM are you running at?
 
   / HELP!!! L4400HST PTO Clutch #9  
I was running at 2000 rpm. If the PTO shaft isn't turning at 2000 rpm, would running at a different rpm make it turn?

No, the pto should work at all RPMs. Unless maybe the hydraulic pressure is right on the edge of operating the clutch pack and that little bit extra helps it operate.
 
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   / HELP!!! L4400HST PTO Clutch #10  
I have attached a PDF of the parts diagrams that relate to the L4400HST.

I would check the fluid levels since the PTO clutch is hydraulically operated.

I haven't really studied this all the way out but it looks to me like the PTO clutch is hydraulically engaged by the movement of the lever that operates the cable that attaches to the PTO clutch valve.

If the valve is not rotating all the way the it would not apply full pressure to the clutch pack.

Could be low hydraulic pressure going to the valve or through the valve.

The clutch pack could have a blown seal in the piston.

I might try to engage and disengage the PTO with the lever (fender mounted) back and forth without a load on the PTO in the hopes the piston or valve may be stuck.

If this doesn't help then I would go through the test procedure in the shop manual to see if you have the proper pressure going to the clutch pack.

Keep us posted.
 

Attachments

  • KUBOTA L4400HST PTO Clutch parts pages.pdf
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