Dog clutch question

Discussion in 'Hubs, Gearboxes, Sprockets and Chains' started by TheNecromancer13, Jan 5, 2016.

  1. TheNecromancer13

    Joined:
    Jan 21, 2015
    Messages:
    610
    Likes Received:
    20
    So I was looking around the other day and I came across this DIY 2 speed dog clutch: http://www.thepixelpump.com/widdershins/how-to-2speed-transmission.php

    Here's a closeup: http://www.thepixelpump.com/widdershins/images/gearbox-2.jpg

    It looks like a useful (and cool) thing to add to my bike.

    So, my question is, what if (looking at second link) I switched the positions of the large and small gears closest to the camera, left the clutch in the same place, and had the engine drive from the left side, meaning I could have gear reduction before the clutch itself. Then the gears would be spinning more slowly and thus be easier to engage without clashing, which as far as I can tell would be a problem with this gearbox the way the other guy mounted it, because the clutch has no syncro (at least that's the theory) and as far as I can tell he has all the gear reduction after the clutch. Anyone see any catastrophic flaws in my idea? Or any other reason not to try building one of these? (I have ideas to mod it and make it more compact than this guy did (his went on a gokart), so size isn't a concern)
     
  2. sbest

    sbest Member

    Joined:
    Nov 3, 2015
    Messages:
    343
    Likes Received:
    2
    Dog clutches are pretty common on lathes where the expectation is you will turn the machine off, and outboard motors where they actually reverse a running motor. The non-syncro gearboxes that those of us over 50 had in our first jalope are basically dog clutches.

    It is the difference in speed between the two plates that makes engagement difficult, but typically you are right, reduction in speed makes engagement easier. Gear reduction tends to put more torque on the clutch and requires parts to be heavier. Often the teeth of the clutch are ground to be self engaging, but I have seen ones in industry with 45 degree teeth activated and held by magnet or air pressure.

    Steve
     
  3. MEASURE TWICE

    MEASURE TWICE Well-Known Member

    Joined:
    Jul 13, 2010
    Messages:
    2,339
    Likes Received:
    313
    I was wondering at first if I had seen this before, but it was of the other type. I mean rather than kinda parallel gearing, a serial gearing.

    The type that uses centrifugal clutch (automatic switching). After the first clucth of two speed transmission engages, you have to wait till speed is increased for the next in one or more of a series of centrifugal clutches to engage that gear up for faster speed. Some kinda bearing, forgot the name allows slippage an or one way rotation only at lower speeds, something like that. What is it called?

    MT
     
  4. sbest

    sbest Member

    Joined:
    Nov 3, 2015
    Messages:
    343
    Likes Received:
    2
    Yeah, the teeth can take many forms, buttress teeth are common when the power is in one direction and some over-running is desired. Square or acme style teeth are common too, and a lot of the gear I worked on had simple Vee type teeth.

    Hmmm? A freewheel or one way bearing? Spragwheel?
    Planetary gearsets often use one to get 2 speed ratios with one or two clutches. The Ford Model T and GM Powerglide are examples of this. No dogclutches involved in either of these.

    Steve
     
  5. Russell

    Russell Well-Known Member

    Joined:
    Apr 19, 2009
    Messages:
    1,233
    Likes Received:
    72
    The dual automatic clutch 2 speed is what I refer to the RUPP 2 speed. They were used on many RUPP(and other) mini bikes and were very dependable. There are a few threads posted on this site about the dual clutch setup.

    This dog clutch type setup is a very basic dependable(non automatic) 2 speed. A variation of this basic design has also been used in a FWD/REVERSE setup.

    Necromancer, Thank you for this thread, when I get some I'll try to it into one of my bike builds.
     
    #5 Russell, Jan 6, 2016
    Last edited: Jan 6, 2016
  6. MEASURE TWICE

    MEASURE TWICE Well-Known Member

    Joined:
    Jul 13, 2010
    Messages:
    2,339
    Likes Received:
    313
    What I was referring to was Sprag Bearing (Sprag Wheel) and specifically from Beginner01 created thread named:

    3+ speed automatic jackshaft idea

    http://motorbicycling.com/showthread.php?t=59169&highlight=automatic+shift

    See photo at

    http://motorbicycling.com/showthread.php?t=59169&highlight=automatic+shift&page=4

    post #37 on Page 4

    ------------------------------

    The not automatic type Dog Clutch:

    I do understand the manual shift for gears though, that looks like what is like going through a neural when clutch plates in the center don't press on anything, then either left or right. Center is neural. Then either left or right when plates contact has a different ratio, so it is essentially switching gears.
     
    #6 MEASURE TWICE, Jan 6, 2016
    Last edited: Jan 6, 2016

Share This Page