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Gravely - blades wont engage

Discussion in 'Mechanic and Repair' started by maklawn, Jun 5, 2009.

  1. maklawn

    maklawn LawnSite Member
    Messages: 4

    I have a Gravely 44z that has 86 hours on it and the blades won't engage. have tried replacing the PTO switch, no help! It doesn't sound or feel like it is trying...something electrical? Anyway, my local dealer went belly up apparently and there is nowhere within an hour of me to take this in...does anyone have any suggestions?
  2. DT Lawn Care

    DT Lawn Care LawnSite Senior Member
    Messages: 850

    Did you check your fuses? It should be either that or unfortunately, your clutch.
  3. maklawn

    maklawn LawnSite Member
    Messages: 4

    Honestly, they look ok, but i guess i could replace them just in case. I'll give that a try. They are just standard fuses aren't they...nothing special about them?
  4. DT Lawn Care

    DT Lawn Care LawnSite Senior Member
    Messages: 850

    They should be. Probably standard size, I doubt that they'd be minis. Good luck.
  5. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Messages: 2,249

    After you check the fuses and they are OK, disconnect the wiring harness to the clutch and with the engine running with blade switch on check the wiring harness for adequate DC voltage to operate the clutch, normally 13+ volts. If you have proper voltage at the harness then you have a clutch problem or a broken wire at the clutch. If you don't have voltage at the harness then there are other options you will have to check out: output from charging coil, rectifier/regulator.

    Even though it may now be inconvenient to do so, I would suggest that you take it to an authorized dealer since it is still under warranty.

  6. DT Lawn Care

    DT Lawn Care LawnSite Senior Member
    Messages: 850

    ^^Sounds like a plan, though I would try to find out what it is before I took it to a dealer. GL
  7. brucec32

    brucec32 LawnSite Platinum Member
    Messages: 4,403

    Wow, I have the same problem almost. Gravely ztr (144z), low hours, blades won't engage even though PTO switch has been replaced with another new one to test it. And oddly, the dealer I bought it from also went out of business. I can certainly find another dealer here, though.

    The difference is in my case that usually the blades WILL engage after a few tries, and the problem is therefore intermittent.

    Due to the design of the box where the wiring is stuffed on this mower, the harness that plugs into the PTO switch was somewhat dirty and had a coating of grime/dust on it. Could it just be bad contacts? If so, how does one safely clean the contacts down in the plastic connector? I'd rather try that quick fix first before I start crawling down to unhook the clutch harness and testing with a voltmeter.
  8. brucec32

    brucec32 LawnSite Platinum Member
    Messages: 4,403

    Sounds like it is my clutch $@#!@@#!@#!

    I cleaned the various contacts (just in case)

    I checked voltage at the clutch harness and it's about 13v

    I checked the 30A fuse and it's fine

    I checked the operator presence control and it works.

    Just in case something I didn't understand was going on, I bypassed the OPC and it still wouldn't engage the blades.

    I put another PTO switch I know works on and again nothing.

    Then I get it all back together and pull the pto and it does finally engage the blades. I shut them off and try it again and it engages the blades again. Then a third time and nothing. And after a few more pulls with no luck I give up. So it seems like the clutch does function just not consistently.

    Could this merely be some sort of gap problem in the clutch adjustment? It's only got about 200 hours on the machine so I wouldn't normally expect any problem there.

    Looks like I'll be surfing the velke around those big lawns tomorrow.

    If any of you real mechanics who see these a lot have an idea what might be causing the failure I'd appreciate your input. Thanks.
  9. brucec32

    brucec32 LawnSite Platinum Member
    Messages: 4,403

    Yeah, this is real fun.

    I put a 12v source directly to the clutch via some jumper wires for a second or two and it engages just fine. That seems to indicate it ain't the clutch.

    So I figure I've maybe got the 13v at the clutch plug due to it working intermittently so I decide to test it again since it isn't engaging the blades still.

    I turn on the mower with the clutch unplugged, and ATTEMPT to touch the contacts of the voltage tester to the cord to see what's there and apparently I goofed bigtime and managed to short that out and in about 1 second the wires running to some black boxes started melting. I shut it down immediately but it looks like I can add rewiring that to the dealer's bill. I can't figure what I did except maybe the probe touched both contacts in the fitting and I didn't notice it.

    Now let the sanctimony begin ("you should have used the dealer in the first place, etc, etc).
  10. maklawn

    maklawn LawnSite Member
    Messages: 4

    Thanks for all the replies. I did most of the tests and everything seemed ok. I took it in to a dealer that is an hour away and now I am just waiting for the bad news. Im hoping it is still under warranty. I bought a Skag walkbehind to replace this one, anyway. Anyone interested in a slightly used Gravely? thanks again everyone.

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