1941 Mercury KB-3 “Deluxe Prop”?

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  • Buccaneer

    US Member - 1 Year
    Replies: 6452
    Topics: 958
    #271644

    The prop that came on this motor had a rubber hub bushing that’s
    cogged on the outer side, with a matching cogged plate
    with a shear pin groove.

    What I realized putting it all back together today, is that the lower
    prop shaft brass pin that pinned the wobbler eccentric to the shaft,
    was also driving the prop. The outer cross hole in the
    prop shaft was not used.

    Of course, I forgot all this until after I made new brass pins and tried
    to put it all together how I thought it should be.
    Using a shear pin in the outer shaft hole, raised the prop out too high
    to even see the threads on the end of the prop shaft.

    Confused and dazed, I took the prop off the similar KB-1A that I just
    got. It had no rubber cogged bushing in the prop, and fit on
    the KB-3 like I wanted, using the two brass pins.

    Is the prop with the rubber cogged bushing a “correct” deluxe model version,
    or something someone happen to make work?

    For now, I’m keeping the KB-1A prop on it.

    DSCN5911

    DSCN5908

    DSCN5910

    DSCN5912

    Prepare to be boarded!

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    green-thumbs

    US Member - 2 Years
    Replies: 550
    Topics: 41
    #271688

    Fun, Fun, Fun… trying to sort out 16 square hole (1940) and the 7 slit (1941and some early Post War) Usually a few parts are missing. Usually not always the sane so if you collect several motors the picture becomes clear. If no one else is on the job I can do some basement research and take a few photos,

    Clutch assembly goes together one way and fits into prop snuggly, Someties needs clean out of corrosion,

    Can use sheer pin, but, a little adjustment required.,

    Louis

     

     


    Buccaneer

    US Member - 1 Year
    Replies: 6452
    Topics: 958
    #271693

    Fun, Fun, Fun… trying to sort out 16 square hole (1940) and the 7 slit (1941and some early Post War) Usually a few parts are missing. Usually not always the sane so if you collect several motors the picture becomes clear. If no one else is on the job I can do some basement research and take a few photos,

    Clutch assembly goes together one way and fits into prop snuggly, Someties needs clean out of corrosion,

    Can use sheer pin, but, a little adjustment required.,

    Louis

     

     

    Louis, are you saying there’s clutch disc under the rubber cogged washer
    that engages the shear pin?

    I was wondering if the “guts” of the prop came out, and one could use
    it as a regular prop, like the KB-1A prop?
    I pried on the guts a little, but the rubber is pretty friable, so I didn’t try
    too hard.

    Prepare to be boarded!


    green-thumbs

    US Member - 2 Years
    Replies: 550
    Topics: 41
    #271765

    The rubber portion of clutch often bonds to the metal discs.        I would not try to separate them by force .                                        Other methods might work, but, I have not tried them.

    The clutch is premium feature for KB-3 that KB-1 and KB-1A did not have originally, but, one that could be added later. . It is also possible to remove the clutch and use a sheer pin so by using the same parts as a KB-1 or KB-1A used.

    Louis

     

     

    I


    Buccaneer

    US Member - 1 Year
    Replies: 6452
    Topics: 958
    #271773

    The rubber portion of clutch often bonds to the metal discs.        I would not try to separate them by force .                                        Other methods might work, but, I have not tried them.

    The clutch is premium feature for KB-3 that KB-1 and KB-1A did not have originally, but, one that could be added later. . It is also possible to remove the clutch and use a sheer pin so by using the same parts as a KB-1 or KB-1A used.

    Louis

     

     

    I

    Thanks Louis, I seen a slot machined across the
    prop bore, down below the rubber cog a ways,
    that I thought might be a shear pin groove, but it
    looked to be cut square, instead of rounded like
    most shear pin grooves.
    I guess I won’t know unless I get the rubber “guts”
    out of the prop.
    I prefer the conventional shear pin set up on the
    “no thrills” version.

    Prepare to be boarded!


    dave-bernard

    US Member - 2 Years
    Replies: 1939
    Topics: 29
    #271780

    the prop shaft on some has 2 holes for shear pins. so, you can use clutch or no clutch.


    Buccaneer

    US Member - 1 Year
    Replies: 6452
    Topics: 958
    #271782

    the prop shaft on some has 2 holes for shear pins. so, you can use clutch or no clutch.

    I’ll try again to dig the rubber clutch works out.
    The rubber has seen better days, so I might
    as well go for broke! Thanks.

    Prepare to be boarded!


    Buccaneer

    US Member - 1 Year
    Replies: 6452
    Topics: 958
    #271805

    As you mentioned Louis, the rubber hub did come out of the prop,
    and I was able to remount the prop without it, and using
    the shear pin in the upper driveshaft hole, like I wanted.

    DSCN5947

    Prepare to be boarded!

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    green-thumbs

    US Member - 2 Years
    Replies: 550
    Topics: 41
    #271843

    Well and GOOD!  It is a good idea to  use 3/16 ” brass rod for sheer pin stock. Steel pin has no give  so when prop strikes something at speed something else give$.

    The pocket in rear side of propeller hub should have a rubber disc and a washer with a smaller O,D, than the pocket so the prop nut can compress it and thus force the prop notch to tightly engage the sheer pin. Standard washer needs to be turned down to fit properly.

    There is a lot of fine detail thinking in Kiekhaefer design. Prop shaft was same from first K-1 in 1940 thru the last Wizard WG4.

    Louis

     

     

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