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PTO Problem - Jacobsen 12HP Gear Drive Closed Side


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#1 Irontooth OFFLINE  

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Posted May 04, 2015 - 11:51 AM

This morning, I started to mow my lawn, but the engine started to die. On a level driveway, the engine couldn't power both the wheels and the deck, but could power the wheels just fine. I disconnected the belt from the 42" deck, and I could easily rotate the blades by hand using the deck drive pulley. With the deck drive belt removed completely, the engine started to die when I turned the PTO on! There was also a burst of white smoke from the front of the tractor that didn't look quite like smoke from the muffler. The tractor has also recently had an intermittent 'vibration' that was related to changes in mowing conditions (lighter to heavier), which felt sort of similar to the blades scalping the grass, when no scalping was happening.

After the tractor cooled down, I could turn the PTO on, and could hear it click on and off with no apparent change in the engine RPM, but couldn't observe it because of the seat interlock, and my dog won't tell me what he sees...

This seems to me like a bearing problem in the PTO.

Any thoughts as to repairing the PTO?. Sourcing a replacement bearing (if applicable) or a replacement PTO?. Other ideas?

Thanks!
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#2 KennyP ONLINE  

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Posted May 04, 2015 - 12:55 PM

This morning, I started to mow my lawn, but the engine started to die. On a level driveway, the engine couldn't power both the wheels and the deck, but could power the wheels just fine. I disconnected the belt from the 42" deck, and I could easily rotate the blades by hand using the deck drive pulley. With the deck drive belt removed completely, the engine started to die when I turned the PTO on! There was also a burst of white smoke from the front of the tractor that didn't look quite like smoke from the muffler. The tractor has also recently had an intermittent 'vibration' that was related to changes in mowing conditions (lighter to heavier), which felt sort of similar to the blades scalping the grass, when no scalping was happening.

After the tractor cooled down, I could turn the PTO on, and could hear it click on and off with no apparent change in the engine RPM, but couldn't observe it because of the seat interlock, and my dog won't tell me what he sees...

This seems to me like a bearing problem in the PTO.

Any thoughts as to repairing the PTO?. Sourcing a replacement bearing (if applicable) or a replacement PTO?. Other ideas?

Thanks!

Sounds like the PTO bearing. I haven't taken one of those apart as yet.



#3 tater195 ONLINE  

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Posted May 04, 2015 - 01:09 PM

a locked up bearing wont make much of a difference once the mag clutch engages. It would make it hard to crank with PTO disengaged.  Sounds like a PTO brake problem, or FOD



#4 crittersf1 OFFLINE  

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Posted May 04, 2015 - 01:27 PM

Are you sure it's not a fuel problem?



#5 propane1 ONLINE  

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Posted May 04, 2015 - 02:04 PM

May not be charging the battery. Not enough voltage to operate engine and electric pto. Could all so be bad engine ground. Just some thoughts. Noel

#6 Irontooth OFFLINE  

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Posted May 04, 2015 - 04:33 PM

a locked up bearing wont make much of a difference once the mag clutch engages. It would make it hard to crank with PTO disengaged.  Sounds like a PTO brake problem, or FOD


I'm probably not visualizing properly how the clutch works. You seem to be saying that it is an electmagnetic clutch with a brake. With the engine off, and belt removed, I can rotate the pulley by hand, but it is a bit difficult, and there is a scraping/gritty feel to it. Is this the brake working?

The forward part of the clutch assembly is mounted to the engine by bolts with springs. Does the electromagnet pull part of the clutch assembly toward the engine, thus engaging the clutch? Is there any resource that could help me understand this better?

I took the tractor out again to do more testing under load. I have one area the yard changes levels. Going up or down between levels naturally makes the deck cut closer, but I have it set high enough to not scalp. When going between levels at first, there was the normal change of load dynamic. After about 5 minutes of mowing, when changing levels, the engine would start to stall. Turning the PTO off would allow the engine to recover. I switched the PTO on again, and continued mowing. The next time I changed levels, the PTO would not immediately re-engage, and the engine started to stall again. After waiting about 10 seconds, the PTO engaged normally and the engine continued to run fine. The next time I changed levels, the PTO would not engage and the engine tried to stall even after waiting a minute or two.

No problems with power to the wheels during this time. Engaging the clutch for the gear drive acted completely normally.

As a further test, since I had installed lights on the tractor, I tried engaging the PTO with the lights on. The taillights, which I can see from the seat, didn't even flicker while the engine was trying to stall.
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#7 tater195 ONLINE  

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Posted May 04, 2015 - 04:46 PM

are the lights frame grounded or wired right to the battery? Im guessing the second one and you have a ground issue. A heat related internal short in the clutch would dim the lights.



#8 Irontooth OFFLINE  

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Posted May 04, 2015 - 06:22 PM

are the lights frame grounded or wired right to the battery? Im guessing the second one and you have a ground issue. A heat related internal short in the clutch would dim the lights.

The lights are frame grounded. The taillights through a mounting hole screw, and the headlights (LED lights) via a wire to the frame. The lights are powered through a dashboard switch, and therefore not normally powered on. The taillights have been installed since last year, but I just got around to installing the headlights. I can't fathom any cause-effect between the headlight installation and the PTO problem, but I'll try pulling the in-line fuse for the lights before my next operational test. That'll be a couple of days, as it's raining now, and I will be working over the next couple of days.

If there is an internal short, am I looking at replacing the PTO? Perhaps my next step should be to remove the PTO assembly and examine the wiring. The wire going into it has a piece of electrical tape wrapped around it between the engine and the PTO mounting plate that looks suspect to me.
image.jpg
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#9 KennyP ONLINE  

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Posted May 04, 2015 - 06:59 PM

That wire with the tape could be the whole issue. It might be close to grounding normally. Then, as things heat up, it is grounding. But, the clutch should free wheel with no power to it. If it is grinding, you have an issue inside there.


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#10 Irontooth OFFLINE  

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Posted May 05, 2015 - 09:34 AM

That wire with the tape could be the whole issue. It might be close to grounding normally. Then, as things heat up, it is grounding. But, the clutch should free wheel with no power to it. If it is grinding, you have an issue inside there.


I pulled the PTO this morning. Once I loosened the retaining bolt and spacer, it spun freely.

Hopefully once I take care the wire (see photo) the problem will hopefully be corrected.

#11 Irontooth OFFLINE  

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Posted May 05, 2015 - 09:37 AM

This is a photo of the PTO power lead:

:image.jpg

#12 Irontooth OFFLINE  

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Posted May 09, 2015 - 06:52 AM

Well, I am somewhat embarrassed about my diagnostic skills. Turns out that this was all caused by a marginal seat safety switch. I should have realized that changing levels in the lawn shifted my weight in the seat, as did leaning forward to switch the PTO on and off. Bypassing the switch cured the symptoms.

I am happy, however, that I fixed the PTO wire, and also discovered and dealt with a bent bracket between the frame and the bottom of the front grill assembly. At some point, somebody must have hung up this tractor on something when in reverse, because I also noticed that the bar on which the belt idler pulleys are mounted is slightly bent. I had already somewhat straightened what looks to be a mounting tab mounted on the plate welded to the front of the frame.

Thanks, all for your assistance...
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#13 skyrydr2 ONLINE  

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Posted May 11, 2015 - 07:16 PM

OOh you lucky duck!!! You have the Agura pto clutch , WAY stronger than the normal one with out the drag break. I frgot who makes the other design, DOH! Kenny might be able to help me here, anyways my 165 had that style before I had a mounting misshap and cooked the windings from a clearance issue.. DOH!!



#14 KennyP ONLINE  

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Posted May 11, 2015 - 07:30 PM

OOh you lucky duck!!! You have the Agura pto clutch , WAY stronger than the normal one with out the drag break. I frgot who makes the other design, DOH! Kenny might be able to help me here, anyways my 165 had that style before I had a mounting misshap and cooked the windings from a clearance issue.. DOH!!

I haven't a clue who made these PTO's. But mine also had that mashed wire issue. I rerouted it out.






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