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  1. E14 PTO Electrical Question 
    #1
    Senior Member Nomad's Avatar
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    Greetings:

    The PTO on my E14 was getting warm when I was using my new forklift (Thanks, Bushman!). Anyway, I bought a new PTO after checking that all my connections were tight, battery pack fully charged, etc. Convinced it was the contactor, right? Wrong!

    Fortunately for me, when installing the new contactor I did not see orange wire 3-02. Without that wire, the PTO can only be activated if you hold the PTO switch in the upper position. Being lazy, I used the forklift like that and kept checking that the PTO contactor was not getting hot. It was fine.

    But here's the deal--I attached orange 3-02 so that I would not have to hold the switch up. Guess what? Hot again.

    I see that 3-02 runs to what's noted as CR-3 on the diagram (is that a diode, there?). Checked that out but I don't have enough electrical experience to tell if a diode is good or bad. Also ran wire 27 back from CR-3 to the PTO switch and noticed that it was slightly loose at the switch connection. Ran out of time to check if securing the loose wire will do the trick.

    My question for the electrical experts is--can CR-3 still work and cause a hot contactor or is this most likely a switch or loose wire issue?

    Any thoughts are helpful and if I could avoid taking the dash apart and/or figuring out how to fix CR-3 that would be helpful.

    Thanks,

    Eric (nomad)
     
     

  2. Re: E14 PTO Electrical Question 
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    I meant to say I bought a new PTO contactor, not a new PTO.
     
     

  3. Re: E14 PTO Electrical Question 
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    Senior Member FarmallMan's Avatar
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    Hi Eric,

    The diode (CR3) is there because of the internal wiring of the PTO switch. It isn't exactly as shown on the schematic diagram. Instead, in the run position only the run terminal is connected to the output to the contactor coil. In the start position BOTH the run terminal (wire 27) and the start terminal (wire 5-03) are connected to the output. The diode is there to prevent the PTO load current from passing through the control switch and wiring. In case you're wondering why the switch is this way, it is designed to be an ignition switch for a piece of equipment with gas engine that would have a coil (run) and starter (start) which would need power continuously and momentarily respectively.

    However you slice it, I don't think that the diode is the cause of your problem. However, I agree it's a strange coincidence. Let's see if we can figure things out.

    Measure the coil voltage when the contactor is latched on (run position only). What do you come up with? Does the contactor get hot if there is no load, but allowed to run for some time? If it can be latched on with no load without getting hot it has nothing to do with the control circuit. If that's the case, then I would suspect that it has more to do with the effect of including the ring terminal on wire 3-02 on the clamping force on the load wire terminals. A way to address this would be to remove wire 3-02, and retighten the nut on the load wire terminals only. Then put the terminal of wire 3-02 on the stud and use a nut off the original contactor to secure it in place. This would insure that the load wire terminals have a good clamping load. This advice assumes that the load studs on the contactor have enough length to permit the use of multiple nuts.

    Nick
     
     

  4. Re: E14 PTO Electrical Question 
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    Hi Nick: I was hoping you would respond! I did check the contactor with 3-02 attached and the switch being activated in run but lift not being used. It does not get hot. It only gets hot when lift is actually used. That should narrow it to a tightening issue you mentioned.

    I will secure the wire that was loose on the switch and I will put that 3-02 wire externally on the contactor so that the larger wires are tighter.

    Will report back.

    Thanks again!

    Eric (nomad)
     
     

  5. Re: E14 PTO Electrical Question 
    #5
    Senior Member Nomad's Avatar
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    Update: That did the trick. Put control circuit wire outside of tight load circuit. Thanks, Nick.

    Ps: Are there other similar contactors that I should be on guard for that might have similar issue or is this limited to PTO?
     
     

  6. Re: E14 PTO Electrical Question 
    #6
    Senior Member FarmallMan's Avatar
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    Any connection that carries a high amperage is subject to this type of heating. The less the clamping load, the higher the possibility of an increased resistance. Even a half ohm at large currents will waste a substantial amount of power (by creating heat). It might be a good thing to go though the other contactors and just make sure that the load terminals are all tight. Another place worth checking is the power disconnect terminals. If everything else seems good, then you're all set. If you have other points where there are overheating issues, then you know how to go about addressing them.

    Just as a side note, hydraulic pumps draw can currents substantially more than you would expect. This may be why you never noticed it before.

    Nick
     
     

  7. Re: E14 PTO Electrical Question 
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    Hi Nick:

    Well, its back at it. Hot again. I might have been too quick to test all the configurations last time. The PTO was still cooling down from being hot and I thought there wasn't a problem. But there is no question that the contactor is HOT when the PTO is "on" but there is no load/no movement. I tested with the PTO being completely cool.

    I haven't had time to take that wire off and check to see the temperature without it on the contactor.

    We might be back to the diode or the PTO switch?

    Thanks,

    Eric
     
     

  8. Re: E14 PTO Electrical Question 
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    I disconnected the orange wire on the PTO contactor and the contactor did not get hot while sitting or while under load (ran fork lift up to max about 8 times).

    I tested the diode based on internet directions and found that one side will register resistance and one side won't, which is how it should be if I am reading correctly that the diode is a gate of sorts that protects the switch from the operational voltage. Not 100% sure on my diode testing skills but that is preliminary.

    Not sure where to go next with this. Can't figure out why it would be hot only with the orange wire on but not in any other configuration.

    In the meantime, the fork-lift is great and I don't see any harm in running it with my left hand holding the pto switch up when I need to lift it. Probably more harm in running it with the orange wire on and the PTO heating up. Thoughts?

    any help appreciated!
     
     

  9. Re: E14 PTO Electrical Question 
    #9
    Senior Member FarmallMan's Avatar
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    Eric, while I think about what could be going on could you provide another bit of information? What part of the contactor is getting hot - the large terminal studs, the small coil studs, or is it the hole thing? Feel around carefully, terminals can get HOT.

    If you have a meter with continuity (beep) mode, it can be used to check the diode. You should get a beep (or low resistance if reading that) with the meter's red wire on the contactor end and the meter's black wire on the switch end. You should not get a beep if you reverse the meter's wires. The diode makes sure that current only flows from the contactor's load terminal to the feed terminal of the switch, and that the switch cannot provide current to the attachment.

    Nick
     
     

  10. Re: E14 PTO Electrical Question 
    #10
    Senior Member Nomad's Avatar
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    Hi Nick. Appreciate the help!

    Contactor gets hot from the very top (flat top) down. it does not get hot on studs. Does not get hot at first in center or bottom. That's probably why I missed the heat the first time because I was randomly touching the contactor, usually in center or bottom and I didn't feel the heat on top.

    The actual fork lift motor never gets hot and nothing gets hot as long as wire 3-02 is not attached.

    I don't have a beeping meter but used the digital and analog. Both show resistance when red probe is on 27 toward the PTO switch but no resistance when red probe is on 3-02 toward the contactor. I think that's consistent with what you expected? Digital meter also has a diode tester that shows values in one direction but not the other but now I forgot which part of diode the red probe was on when I tested.


    Not sure it is helpful but the brake switch will not kill the PTO. It does work to shut off the drive motor. I have not traced wire 24 to see if/where it is connected.

    thanks again,

    Eric (Nomad)
     
     

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