1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How to unscrew a nut from a generator

  1. May 2, 2016 #1
    I was hoping with the academics and engineers present on this forum, somebody could enlighten me. I have a generator with a nut on the end of the rotating shaft. However, if I try to unscrew it, the entire shaft rotates with it, and I can't hold the shaft still because it seems the nut's torque is too great. Is there a way to get it off?
     
  2. jcsd
  3. May 2, 2016 #2

    berkeman

    User Avatar

    Staff: Mentor

    Can you post some pictures?
     
  4. May 2, 2016 #3

    jim mcnamara

    User Avatar

    Staff: Mentor

    Are you sure of the handedness of the threads? i.e., you spun the shaft with a fingernail the thread groove. I have sometimes wasted a few minutes trying to unscrew a nut - the wrong way.
     
  5. May 2, 2016 #4
    http://imgur.com/t0CCxVG
    http://imgur.com/t0CCxVG
    This is a stock generator direct from a seller. We have not yet modified/touched it.
     
  6. May 2, 2016 #5

    1oldman2

    User Avatar
    Gold Member

    What Jim refers to is its not uncommon for the threads securing the nut to be threaded in the opposite direction of shaft rotation.
     
  7. May 2, 2016 #6
    The shaft will turn both ways.
     
  8. May 2, 2016 #7

    1oldman2

    User Avatar
    Gold Member

    This would be normal however you need to define the direction it turns while its generating power.
     
  9. May 2, 2016 #8
    It is in the counter clockwise direction.
     
  10. May 2, 2016 #9

    1oldman2

    User Avatar
    Gold Member

    At this point I usually search for online service manuals, there is undoubtedly a method for locking the shaft regardless of which way the threads turn.
     
  11. May 3, 2016 #10

    billy_joule

    User Avatar
    Science Advisor

    Presumably the sprocket is splined or keyed to the shaft, have you clamped the sprocket to hold the shaft? Scrap wood will prevent tooth damage.
     
  12. May 3, 2016 #11

    Baluncore

    User Avatar
    Science Advisor

    Get a short length of roller chain that fits, then drop it over the sprocket. Google images 'chain pipe vice'.
    Hold the sprocket by the chain in a vice, or with a Stilson pipe wrench, the chain will protect the sprocket teeth.
    Then undo the nut by turning it forwards and backwards with ever increasing torque.
    At some point the nut will turn easily and come off the threaded shaft. You will then know if it is LH or RH threaded.
    If it is a tight fit you may then need to use a puller to remove the sprocket from the keyed shaft.
     
  13. May 3, 2016 #12

    jim hardy

    User Avatar
    Science Advisor
    Gold Member
    2016 Award

    I like the chain idea - how practical !
    Or get a 1/2 inch drive socket that fits the nut
    ask the guys at your local tire shop(or a handyman neighbor) if they''ll spin it off with their "impact wrench"


    First though, it would be prudent to call whoever sold you the generator and ask whether it's left or right handed threads.
     
  14. May 3, 2016 #13
    You may need to use some impact. Like a box end wrench on the nut and a hammer. And note that if the nut and shaft are threaded to "tighten" in normal use then the nut would come loose turning it the same direction as normal rotation. I'd go with right hand as a first guess unless you can see some threads.
     
  15. May 3, 2016 #14
    So to ensure I'm doing this right, I'm basically trying to hold the shaft still with the chain via a pipe wrench?

    Thanks! I will definitely try this.
     
  16. May 3, 2016 #15

    Baluncore

    User Avatar
    Science Advisor

    Yes.

    Your picture shows a nut with a rounded outer surface. That looks like a “nylock” nut which will almost certainly be a right hand thread.

    I am a bush engineer when I do not have all the tools I need. To do this job I would simply rest the sprocket on a block of wood with the motor just off the floor or bench. Put a ring spanner on the nut, then hit the end of the ring spanner with another block of wood. The inertia of the rotor will prevent rotation during the short initial impact. The block of wood that the sprocket rests on will prevent damage to the motor bearings.
     
  17. May 4, 2016 #16

    jim hardy

    User Avatar
    Science Advisor
    Gold Member
    2016 Award

    "Ring spanner" is a proper British term, for Americans it's "box end wrench".

    Don't expect it to budge on first blow.
     
  18. May 4, 2016 #17

    CWatters

    User Avatar
    Science Advisor
    Homework Helper

    Doing it up again might be harder.
     
  19. May 4, 2016 #18
    My thought, too. Are you sure you need to remove the nut ? Are you changing the sprocket? Or has removing the nut become a challenge in itself?

    If it must come off, a chain around the sprocket and use of an impact wrench would probably be the safest approach.
     
  20. May 4, 2016 #19

    jim hardy

    User Avatar
    Science Advisor
    Gold Member
    2016 Award

    Check tool sales . I found an el-cheapo electric impact wrench ½"drive for $40 at one of the import discount store sales. It's just right for little jobs like this and you dont have to have an air compressor. Paid for itself on first use.
     
  21. May 4, 2016 #20
    There is a special pipe wrench called a (chain wrench)

    http://www.bing.com/images/search?q...54ddcdb848c8e9b6b76dd1c2721daa31o0&ajaxhist=0

    You have to cut a small block of wood to put on the jaw but it will hold it so you can remove the nut. baluncore and Billy_joule were on the right track. I have had to deal with these before and they are a pain in the butt!

    Note: if the sprocket has a keyway keeper (shear pin) you WILL probably dent it and need to replaced it unless you have an impact gun.
     
    Last edited: May 4, 2016
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: How to unscrew a nut from a generator
Loading...