John Deere F510 PTO issues

[scott69101]

Need some advise: We have two John Deere F510 front mowers at our Bible Camp; one with about 350 hours and the other with about 700 hours. They both start, run. and move like they should, but they both suddenly developed PTO problems. The older one was mowing one day, but the blades suddenly stopped spinning and billows of smoke started coming from under the engine. Did some checking, and found the PTO fuse blown, no continuity across the PTO switch terminals that engage the PTO clutch, and no continuity across the PTO clutch wires. So I assume the PTO clutch cooked and wiped out the switch and fuse. But a couple of days later, the newer F510's blades suddenly stopped spinning. Found and replaced a blown fuse, and the thing started mowing again - for about 10 minutes. Again found the PTO fuse blown, but also found no continuity across the PTO switch terminals that engage the PTO clutch. The clutch wires have continuity, but not much. From looking at the JD wiring diagram, I assume these PTO clutches are 12 volt DC and they should clunk when hooked across the battery. Does anyone know what the correct resistance reading and operating amperage should be for a good clutch? And can anybody suggest why both these mowers should suddenly have PTO issues?

 

[Kernopelli]

As far as why both went out at same time.......it has to simply be a coincident.

I can not give specifics to that clutch but from reading, the bigger/wider the clutches air gap the higher amp draw it requires......may be why the one continues to work but then blow fuses. There are a lot of sites online that discuss electric clutch troubleshooting, how to adjust a electric clutch ( looks like average air gap is about .015") , various makes voltage draw (average maybe 4-6 amps) and resistance parameters ( average 2-4 ohms).

http://www.warnernet.com/pdf/819-0458_p-1097-6.pdf or http://www.ganos.com/electricclutchtesting.pdf gives good PDF's examples of how most clutches are designed and troubleshooting, etc.

Google "electric clutch amperage" or electric clutch troubleshooting" to find sites discussing general problems/solutions to clutch issues.

 

[scott69101]

Thanks Darryl. Could be a coincidence, but it seems odd. I'll pull them out and see what they look like.

 

[scott69101]

Hey Darryl- downloaded the Wagner link that you suggested. It said that the minimum resistance is 2.4 ohms. The PTO I'm working on now reads .9 ohms. So I took it out, opened it up, and found a crispy electromagnet. Guess I'll be buying a new clutch for that one. Then I'll tear into the other mower. Good thing it's been dry here lately. Thanks for your expertise.