L3400HST overrunning clutch explanation?

   / L3400HST overrunning clutch explanation? #1  

canoetrpr

Veteran Member
Joined
Aug 7, 2005
Messages
2,396
Location
Ontario, Canada
Tractor
Kubota M7040 cab/hyd shuttle - current, Kubota L3400 - traded
Can you help me understand exactly what is a live continous PTO with an overrunning clutch.

This is what I understand - correct me as necessary:

- I need to clutch to start the tractor. I don't really know why but know that it wont start unless I do :).

- I need to clutch when I engage the pto with the switch on the right. Believe the switch is a simple cable driven thing and not hydraulically or electronically actuated.

- Here's the confusion: I was under the impression that I was REQUIRED to clutch to disengage the PTO. I thought it had something to do with getting the PTO shaft and the transmission speed to match. But I think I am reading that I don't have to clutch to disengage?? Isn't there an issue with the PTO running at a different speed than the drive train.

Confused... Can you explain exactly when I need to clutch and why I am clutching at that time? Obviously I don't understand this correcty.

That independant electronically actuated PTO on the grand L does sound pretty cool :)

I started thinking about this because I was reading about the new JD 3203 specs and read that its PTO was independant and activated through electronics.

Just trying to figure out the exactly what the electronics saves you from doing as an operator here in the independant case (L3130, JD 3203 vs. L3400)
 
   / L3400HST overrunning clutch explanation? #2  
You need to push the clutch in to start because there is safety switch on the clutch.

You must clutch to engage the PTO. When the clutch is pressed the PTO shaft stops and allows you to engage an implement that is stopped with no grinding. If you engage without using the clutch you could damage the PTO. Let the clutch out slowly to gradually spin the implement, much like you would start a stick shift car. If you pop the clutch you will cause a shock to the PTO.

Once the implement is engaged and runnning it is safe to disengage the PTO without clutching becasue the PTO and implement are at the same speed. My dealer recommends this.

If you push in the clutch with the PTO engaged, the PTO shaft will stop but the implement will keep spinning. To prevent driving the PTO shaft with energy from a spinning implement there is a one way (over running) clutch. On the L3400HST you can hear it. It sounds like a gear grinding because it is ratcheting.

The elctronic hydraulinc PTO is supposed to graduallty engage to prevent shocking. There are some JD people complaining that the whole tractor shakes when engaging the PTO. On an electric system you have to take what you get. With a clutch you can control the shock by letting it out slower for bigger implements that have a lot of inertia.

I like the manual system much better because there is less to go wrong and I can control the engagement. I have always found that simple is better as far as reliability goes.

The L3400DT has a two stage clutch like my Ford 1910. You still would operate the PTO the same way except you must press the clutch all the way down to disengae the PTO. Half way down stops the tractor but not the PTO.

I hope this helps.
 
   / L3400HST overrunning clutch explanation? #3  
<font color="blue"> The elctronic hydraulinc PTO is supposed to graduallty engage to prevent shocking. </font>
The problem is knowing which tractors feather in the PTO and which don't. I know that my late MF 1250 did and the MF 1440 that I now have does as well as the MF 1500 series. I don't know if any of the other manufactures do or not. They may not by the way some members have posted about harsh engagement.
 
   / L3400HST overrunning clutch explanation?
  • Thread Starter
#4  
ccsial:

That helps a lot.

I'm still scratching my head however as to why the manual says that I should use the clutch when shifting the PTO lever.. that implies that I should do it when engaging and disengaging. Sounds like disengaging without the clutch works just fine for you.

I guess disengaging without clutching just never uses the overrunning clutch at all right?
 
   / L3400HST overrunning clutch explanation? #5  
<font color="blue">( The L3400DT has a two stage clutch like my Ford 1910. You still would operate the PTO the same way except you must press the clutch all the way down to disengae the PTO. Half way down stops the tractor but not the PTO. )</font>

Are there two clutch disks? How does this work? Dealer couldn't even tell me. /forums/images/graemlins/confused.gif
 
   / L3400HST overrunning clutch explanation? #6  
see the attachment for a parts breakdown.
 
   / L3400HST overrunning clutch explanation?
  • Thread Starter
#7  
Something wrong - I don't see an attachment.
 
   / L3400HST overrunning clutch explanation? #9  
One More time. /forums/images/graemlins/frown.gif
 
   / L3400HST overrunning clutch explanation? #10  
</font><font color="blue" class="small">( <font color="blue"> </font> I guess disengaging without clutching just never uses the overrunning clutch at all right?)</font> <font color="black"> </font>

That is true.

There is nothing wrong with using the clutch to disengage. The reason not to, is to avoid the ratcheting (grinding) noise of the over running clutch. You'll notice that if you have a high inertia implement like a bush hog, reducing the throttle fast while engaged will cause the clutch to ratchet.

I don't use the clurtch to disengage the PTO on the 1910 either and it does not have an over riding clutch. It's just easier.

Kubota has an optional fix, PSB-2005-052, that raises the oil level in the transmission to cover the clutch and quiet the ratcheting sound. I will not do that fix because I avoid the sound by not clutching on disengage. The fix adds 7 Liters of hydraulic oil.
 

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