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I have had trouble using the search function here, so I need to ask a question regarding the PTO on my Gravely ZTX-42. The mower has just over 160 hours on it and a week or so ago, the PTO started to intermittently disengage while mowing my approximately 1 acre lawn. I removed the PTO switch and it tested out as it should in both the engaged and disengaged positions. I checked for nicked wires as best I could and found none. It seems like it runs fine for the first 20 to 30 minutes from a cold start but then it will only stay engaged for a few seconds to a minute or so each time i switch it off and back on. Has anyone else had this issue who can offer some suggestions? One thing I should probably note is that I do know the battery is bad. I have been jump starting the mower for the past year as I have had difficulty finding a replacement that will fit. Is there a minumum voltage that the PTO needs in order to stay engaged? Today when it happened, I tested the voltage at the battery, and it read just over 8 volts. I have tried in vain to charge it but I cannot get it over 10 volts.

Any insight will be greatly appreciated.

I would start with a new battery. Lawnmower batteries have standard dimensions so other than determining if the + post is on the left or right any lawnmower battery will fit in the battery location. Also need to pay attention to the CCA rating of the old battery and try to get something close or higher than the existing battery, If the battery voltage drops below a certain point the clutch will disengage. And on some mowers can also effect the charging system effectively shutting down the voltage regulator output.

ILENGINE said:

I would start with a new battery. Lawnmower batteries have standard dimensions so other than determining if the + post is on the left or right any lawnmower battery will fit in the battery location. Also need to pay attention to the CCA rating of the old battery and try to get something close or higher than the existing battery, If the battery voltage drops below a certain point the clutch will disengage. And on some mowers can also effect the charging system effectively shutting down the voltage regulator output.

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Thank you for the input. I believe you may very well be correct that the battery is likely the issue, but a regular old garden tractor/lawnmower battery will not fit in the compartment on this particular mower. The OEM battery is much lower profile and while the bracket is somewhat adjustable, I have already attempted to install two different batteries from two different sources, and neither of them would fit properly enough to be secured in the designated space. They are either too tall, or the posts are positioned such that they interfere with attaching the bracket. My local battery supplier has told me that he cannot keep this particular battery on the shelf because there are precious few suitable substitutes in the current supply chain.

The only stators I have replaced came from mowers where the owners for one reason or another had ben running witha flat battery
This causes the alternator to be running at full output all the time, some thing very few are designed too do so they over heat and melt the plastic parts then cook the rectifier as well
So for the sake of a $ 100 battery they end up with a $ 400 repair bill ( $ Aus) .
Even worse for you in all 10 cases the mower was running fine and in 3 cases they told me to "take a hike" and kept on running the mower the same way and in one case running low voltage also burned out the clutch coil to boot and that was another $ 900
So check your alternator output you should see 13.5 to 15V at the battery terminals with the engine running .
If not then you have cooked your altinator and perhaps even the clutch .

Crustyoldcurmudgeon said:

Thank you for the input. I believe you may very well be correct that the battery is likely the issue, but a regular old garden tractor/lawnmower battery will not fit in the compartment on this particular mower. The OEM battery is much lower profile and while the bracket is somewhat adjustable, I have already attempted to install two different batteries from two different sources, and neither of them would fit properly enough to be secured in the designated space. They are either too tall, or the posts are positioned such that they interfere with attaching the bracket. My local battery supplier has told me that he cannot keep this particular battery on the shelf because there are precious few suitable substitutes in the current supply chain.

Click to expand...

Went and looked at that is a special battery. 12v 190 amp AGM SLA battery similar to what is used in emergency exit lights.

bertsmobile1 said:

The only stators I have replaced came from mowers where the owners for one reason or another had ben running witha flat battery
This causes the alternator to be running at full output all the time, some thing very few are designed too do so they over heat and melt the plastic parts then cook the rectifier as well
So for the sake of a $ 100 battery they end up with a $ 400 repair bill ( $ Aus) .
Even worse for you in all 10 cases the mower was running fine and in 3 cases they told me to "take a hike" and kept on running the mower the same way and in one case running low voltage also burned out the clutch coil to boot and that was another $ 900
So check your alternator output you should see 13.5 to 15V at the battery terminals with the engine running .
If not then you have cooked your altinator and perhaps even the clutch .

Click to expand...

Thank you for this input. I had no idea running with a low battery could cause such issues. I will certainly test it tomorrow. My son-in-law has a similar mower with the same battery that is definitely good. He is going to loan it to me to see if that fixes the issue. I ordered a battery today that is supposed to be here in approx 2 weeks. Hopefully I have not already done irreparable harm.

ILENGINE said:

Went and looked at that is a special battery. 12v 190 amp AGM SLA battery similar to what is used in emergency exit lights.

Click to expand...

The local Batteries + Bulbs store here has ordered one for me this afternoon. They are telling me it will be about 2 weeks before I see it. I'm borrowing one in the meantime. Thanks again for your input.