How best to remove a small gear?

  1. Rannsachair

    Rannsachair Forum Supporter

    Messages:
    1,072
    Location:
    Lochgilphead, Argyll, Scotland
    I partially striped an old AJS engine http://www.mig-welding.co.uk/forum/threads/a-wee-matchless-project.75104/ and am now struggling to remove the 1" diameter timing pinion. Left hand thread nut has been removed and it is on a keyed tapered shaft
    [​IMG]
    I have tried the following:

    A Couple of different pullers with the ends of the legs ground down as there is only 0.1" clearance:
    [​IMG]

    [​IMG]
    No luck, Have tried shocking the puller by giving a sharp whack with a heavy hammer with the crankcase supported on blocks of wood.

    So then tried heating the gear for a few minutes with a gas torch and tried as above -still no luck

    I have spent more time trying to get this gear off than I took to strip the rest of the engine!

    So what next?

    I can still buy a new pinion for under £25, so not a complete disaster if I carefully cut it off, but last resort.

    Any suggestions appreciated, thanks
     
  2. slim_boy_fat

    slim_boy_fat Forum Supporter

    @Rannsachair How long have you been leaving it under pressure of the puller? I remember struggling to remove the hub of a Toro ride-on greens mower
    and going through all the stages you describe. In the end I got fed up and went home for the day, leaving the puller screwed tight on the hub.

    Came back next day prepared to do battle and the bits were lying at the other side of the shed - it must have released during the night. I wouldn't have wanted to have been in line with it when it finally parted company with the rest of the machine.......:o
     
  3. Spark plug

    Spark plug Member

    Messages:
    3,246
    Location:
    Durham, England
    The first thing I would try is, get a suitable lever to apply a little pressure from behind the gear, the use an air chisel to shock the end of the shaft.

    I stumbled across this method when trying to find a non destructive method for removing flywheels from small Briggs and Stratton engines, it may sound a bit extreme but it is rather delicate and works extremely well.

    Good luck.
     
  4. Maker

    Maker nEw mEmBeR

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    Don't ask questions
    Have you tried giving it a some heat? Looks like a perfect job for one of those cheap Chinese induction heaters on eBay:D.
     
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  5. rtbcomp

    rtbcomp Moderator Staff Member

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    Sheffield UK
    When you whack the puller place crankcase on something with a bit of give in it, that way the shaft has somewhere to go and the puller & pulley will lag behind a bit before they realise what's happened.

    Similar principle to holding a propshaft in your hand and whacking the yolk to dislodge the bearing cap.
     
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  6. cumbriasteve

    cumbriasteve Moderator

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    Location:
    Cumbria UK
    I had a similar one on a BSA, it would not budge and I was at risk of causing more damage to the surrounding parts, I then remembered a tip from an old guy who had a collection of flat tankers.

    Put your puller back on, give it a couple of sharp taps whilst suspending the unit, add plus gas and then each day do the same, just a couple of taps nothing more and try to nip the puller even by the smallest amount, day four mine popped off on the first tap.
     
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  7. lchris21

    lchris21 Member

    Messages:
    1,183
    Location:
    South Wales
    bit of maths might help.....:D:D:D

    using the rule Force = Pressure x area.

    If you can get a 3 leg puller in there, the extra leg will add an additional 50% increase in force applied to the gear for the same pressure on the forcing screw due to the increase in surface area you got pulling underneath the gear... bung in a bit of heat......cuss and swear a bit and let physics take over.

    My physics is a bit rusty.....but, For example......
    F=PXA
    25N = 5N/mm2 x 5mm2 (1 leg)
    50N = 5N/mm2 x 10mm2 (2 leg)
    75N = 5N/mm2 x 15mm2 (3 leg)

    Used this principle in the past to get a TR bearing off a pinion without damaging either....Good luck :thumbup:
     
  8. rtbcomp

    rtbcomp Moderator Staff Member

    Messages:
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    Location:
    Sheffield UK
    All the third leg does is distribute the same pressure/force more evenly. It's the force that pulls the gear off, not the pressure, and in equilibrium the force in the screw equals the force exerted on the gear, irrespective of the number of legs.
     
  9. lchris21

    lchris21 Member

    Messages:
    1,183
    Location:
    South Wales
    Agreed.....don't want to get into a lengthy physics debate, .....but if the pressure on the screw remains the same, and the the 2 legs cannot transmit said force to remove the gear, the additional surface area of the 3rd leg will by maths, increases the force acting to remove the gear....................had this debate with an engineer with too many qualifications than he knew what to do with 20 years ago when he brought me the afore mentioned pinion.......:whistle:
     
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  10. pedrobedro

    pedrobedro Man at Matalan

    Messages:
    9,803
    Location:
    CX Derbyshire
    We had that doing a gearbox. Tightened the puller up and tried hitting it then gave up and as I walked away from it there was a bang and it flew about 4 feet in the air. In your last picture it looks like it's pulled up as far as the threads on your puller.
     
  11. Maker

    Maker nEw mEmBeR

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    Don't ask questions
    I'd say your physics is very rusty:whistle:. By the same logic using a puller with thicker legs will make it pull harder;).

    Pressure doesn't really matter for this problem anyway.
     
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  12. Rannsachair

    Rannsachair Forum Supporter

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    I think he was pulling your leg :doh:
     
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  13. brightspark

    brightspark Member

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    yarm
    grind some steel taper wedges and taP them in behind the pinion warm it up and tap the end of the shaft with a copper hammer
     
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  14. Luke

    Luke Forum Supporter

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    Whitchurch, Shropshire
    Worth a try, especially if there is even the tiniest bit of end-float on the shaft.
     
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  15. Seadog

    Seadog Forum Supporter

    Messages:
    4,505
    Location:
    NE London - UK
    Having stripped my 500 single more times than I care to remember you need to tighten and tap, tighten and tap. Repeat until it pops off. I eventually acquired a genuine puller, but that was after I'd got rid of the bike:( Sold that in 2013 when I cleared out all of my factory tools.
    My first efforts at the tender age of 19 involved tyre levers, but this does damage the web and the gaskets faces due to the lack of room around the pinion.
     
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  16. lchris21

    lchris21 Member

    Messages:
    1,183
    Location:
    South Wales
    0.1" clearance is the key.......;) anyway, this might help the original poster..........:whistle:google clamshell bearing pullers and fire up the lathe
    35 years on the tools and counting......never failed to get a bearing/gear/pulley off.......there's always tomorrow I suppose :D
    upload_2017-8-20_12-51-27.jpeg
     
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  17. mfletch

    mfletch Member

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    431
    Location:
    Mansfield
    Use a bit of heat with puller on
     
  18. Rannsachair

    Rannsachair Forum Supporter

    Messages:
    1,072
    Location:
    Lochgilphead, Argyll, Scotland
    Thanks guys :clapping: , I used a combination of leaving the puller on under load the odd hammer blow and release oil, now looks like:

    [​IMG]

    @Ichris21 Hitchcocks do a tool like that for removing pinions, 2nd bottom of the page.
     
  19. rtbcomp

    rtbcomp Moderator Staff Member

    Messages:
    18,615
    Location:
    Sheffield UK
    Thanks for letting us know :thumbup:
     
  20. slim_boy_fat

    slim_boy_fat Forum Supporter

    Isn't this a great place :thumbup: Glad you prevailed.
     
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