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  1. #1
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    Default Tapered fitting to shaft

    My mate has a chipper/mulcher.

    It threw a blade which bent the crank.


    Removing the cutter disk from the crank, which is a taper fitting locked with an axial bolt proved extraordinarily difficult even with a gear puller. (bent the plate...)

    The plate was off not long ago so I was surprised how difficult it was.

    Even removing it after assembly (which was when the bend was found) was difficult.

    He used grease on the shaft. Is this correct /ok/bad?



    Russ

  2. #2
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    Default

    It sounds a bit of a odd bod to me Russ, I lost count a long time ago of how many chippers that I have had to repair and they all had a parallel shaft and a key.
    Generators have a tapered shaft and the odd pump may have also.
    Typically you don't lube a taper as when you tighten the bolt that pushes the whatever onto the taper and it normally has a torque spec to push it on so far/tight and that would likely be dry unless otherwise specified.
    So I think you need to hunt those details up, what make and model is it?

    cheers, shed

  3. #3
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    I vaguely recall our mulsher (5hp Briggs and Straton) had a taper shaft on it.
    Grease on the shaft would make it easier to push the tapered socket up the shaft for a given torque, so probably not recommended if you want to disassemble easily.
    Michael

  4. #4
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    Default

    If I were to put any thing on the taper I would use never seize

  5. #5
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    G'day Russ,
    When refitting aluminium flywheels on tapered lawnmower motor cranks I always dust the shaft with some graphite, this helps with smoother seating of the taper when torquing the retaining nut and makes them easier to remove next time.
    Cheers,
    Greg.

  6. #6
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    When you assemble a shaft coupling it helps to undersand what is it actualy doing, how does it work......
    Most of the forces on it are torsional, but in this instance you also have shock forces and vibrational forces and aslo significant enertia forces when these forces oppose each other.
    So a tapered shaft coupling is basically 2 opposing tapers forced together with a nut or bolt to form a compression joint that relies on friction between the 2 mating tapers to transmit torque.
    So what do you think will happen when you add a lubricant to this coupling that relies on friction to transmit torque?
    If it is a part that needs to be removed often for maintenance then drill and tap a hole either side of the boss to utilize a puller that wont bend the blade carrier. Something that will put pressure on then a spot of heat and the taper will let go.
    Dont go bashing the thing as you can crack the crankcase on the engine under the flywheel.

    Cheers, shed

  7. #7
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    Default

    Oops

    My bad...brain freeze... Tapered fitting to shaft

    It is of course a straight shaft with keyway. I have no idea where the idea of a tapered shaft came from. Tapered fitting to shaft

    If it was a taper it would release almost immediately it moved but we had to use the puller almost the whole length.


    Definitely impact load but it wasn't run after the blade was replaced, the bent crank was noticed and it was removed again. And seemed to be even tighter...



    Russ

  8. #8
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    Russ it needs to be a fairly tight interferance fit otherwise the key and keyway will flog out.
    It would likely also flog out if you put never seize on it, i have seen this a few times where mowing contractors put never seize on the disc bosses to aid in removal, they fairly soon become a sliding fit on the shaft and the keys and keyways flog out.
    At installation i would just give it squirt of wd40 to help it slide on.
    The cranks can be hard to hold to straighten depending on the orientation of the bend in relation to the balance weights.
    I have also been able to straighten a couple with a strategic wack with a copper hammer, you dont do this with the crank in the engine.
    If you need a crank there is a slim chance i might have one if it is a briggs engine???


    Cheers, shed

  9. #9
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    I have removed a few taper fitting in the past with the homemade extractor. while the bolt on the extractor is under pressure, I use copper mullet to tap on the end of the bolt gently...
    Attached Images Attached Images

  10. #10
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    Quote Originally Posted by shedhappens View Post
    If you need a crank there is a slim chance i might have one if it is a briggs engine???


    Cheers, shed
    Shed , it's a 5.5hp b&s.

    Be spectacular if you do... Tapered fitting to shaft

    Russ

  11. #11
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    Quote Originally Posted by russ57 View Post
    Shed , it's a 5.5hp b&s.

    Be spectacular if you do... Tapered fitting to shaft

    Russ
    No, sorry nothing that small.
    If you dont have the tools to straighten it and you need a hand with the repair let me know.

    cheers, shed

  12. #12
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    Quote Originally Posted by jackaroo View Post
    I have removed a few taper fitting in the past with the homemade extractor. while the bolt on the extractor is under pressure, I use copper mullet to tap on the end of the bolt gently...
    What, The fish or the haircut???

  13. #13
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    The fish obviously. Getting hold of a bogan with red hair is difficult at the best of times.

    Michael

  14. #14
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    Quote Originally Posted by Michael G View Post
    The fish obviously. Getting hold of a bogan with red hair is difficult at the best of times.

    Michael
    Not round here, it's not.....

    PDW

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