Announcement

Collapse
No announcement yet.

Sprag clutches, silent, strong, instant engagement.

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Sprag clutches, silent, strong, instant engagement.

    Onyx Hubs uses them, but in a high end hybrid bearing setup. I like the full floating axle setup. Load and drive carried separately. I'm not sure why anyone bothers with ratchet pawl type clutches. Multiple pawls, but only one engages at a time, noisy, slack between engagement points. Sprag clutches are used in automatic transmissions. They're off the shelf tech. Why can't we have nice stuff.
    Video: How an Onyx instant engagement hub works Sprag Clutch – Onyx Racing Products uses sprag clutches in its rear bike hubs. Sprag clutches are unique because they engage instantly but operate silently. In addition, all sprag elements maintain gentle contact with the driver and hub body, gliding with minimal friction until torque is applied. Their […]
    Last edited by Retrorockit; 01-13-2023, 10:48 AM.

    #2
    Originally posted by Retrorockit View Post
    Onyx Hubs uses them, but in a high end hybrid bearing setup.
    https://www.naturalnews.com/2023-01-...-earliest.html
    Natural news topic when I clicked on,? China preparing to launch an invasion of Taiwan, warns Chinese journalist.
    Remembering the 1930`s-1940`s Why should I care I`m not a Chinese Journalist.


    Comment


    • dirtman
      dirtman commented
      Editing a comment
      On 2nd though this could be a major disruption.
      My Luna SRX-Light Bee will might need parts from China soon.

    • Retrorockit
      Retrorockit commented
      Editing a comment
      Sorry I posted the wrong link. Don't worry about the start of WW3 it's not schedules until 2024.
      I fixed the first post.

    #3
    Not that it's important, but has anyone taken apart the BBS motor clutches to see whether they are sprag or the ramp-type overrunning clutches.....

    Sprag:

    Click image for larger version

Name:	sprag.clip_image0023.jpg
Views:	108
Size:	16.8 KB
ID:	159014

    Ramp-type:

    Click image for larger version

Name:	freewhell-unit.jpg
Views:	115
Size:	29.4 KB
ID:	159013


    Comment


    • Retrorockit
      Retrorockit commented
      Editing a comment
      BBSHD has pawls at the pedals, and a roller bearing ramp style in the plastic gear.. The ramps are just formed into the outer bearing race.

    • AZguy
      AZguy commented
      Editing a comment
      That's what I've always presumed but I generally hear people refer to it as a sprag clutch which isn't really the same thing... I know, I know... splitting hairs ;-}

    • Retrorockit
      Retrorockit commented
      Editing a comment
      The ramp roller clutches can double as a roller bearing. Espcially since they're usally under no load when released. The ones in the BBSHD are nice because they have separate roller elements. The TASDZ2 not so much.

    #4
    Have you folks played with the Tongsheng TSdZ2 mid drive? Sprag clutch and torque sensing in a mid drive conversion sounds appealing… Not sure about availability.

    Comment


      #5
      It has many known quality and strength issues. I own one and have hardly ridden it. TSDZ2 people just seem to accept a bunch of crap that doesn't exist in the BBSHD world.
      IMO it's a 350W moyor being run at 750W. It has no cooling as it comes. This can be fixed. Endless sphere has an endless thread on these things. Stripped plastic gears, and snapped pedal shafts abound. if you want to add a throttle a new controller and wiring harness are needed. Those may not come programmed for a throttle. You may need to fabricate a harness to program it ( that's where mine is at right now). You can geek out on the open source firmware (most of the thread is related to that). Basically fixing them is a hobby unto itself. Look before you leap. Compare what you see at the ES TSDZ2 thread to what you see here. I donated a simple cooling mod there.
      Hi, I was made aware of a new offering over at BMSBattery today: "SDZ2 Torque Sensor Central Motor". https://bmsbattery.com/home/803-sdz2-torque-sensor-central-motor.html Seems like a an attractive alternative to the Bafang BBS, $50 cheaper, with torque sensor, better installation guide etc...

      I think the quality of the bearings is questionable, and since some are noisy, some not, somr break others don't I suspect the machine work is inconsistent also.
      I'm too busy riding my BBSHD to be bothered with it.
      I think they got sued by Bafand and had to add a sprag. or maybe they just did ti on their own (unlikely from what I've seen).
      Last edited by Retrorockit; 01-29-2023, 05:49 AM.

      Comment


      • pbreezy
        pbreezy commented
        Editing a comment
        I laughed at this way harder than I should have. Sounds like my experience with RC cars. I guess I know why I don’t hear more about them XD

        Thanks for the insight!

      • Retrorockit
        Retrorockit commented
        Editing a comment
        Go to ES you'll hear plenty.

      #6
      I have a Currie M16 mid Drive motor on an izip bike that uses a sprag clutch, it's the main weak point of that setup and currently the main reason why I can't use the bike, as the company doesn't offer spares. They are prone to breaking if you hit too hard of a bump whenever it's under power, or whenever you are putting too much torque into it on a hill climb under power. Curries tech support basically said they would swap the clutches from known good units to repaired units, and now there's no more left.

      they also require specific lubricants in order to make sure they can slip correctly, and I've had this one apart and it's very difficult to see where the bearing surface is corrupted and why it no longer works.

      ​​​​​​

      Comment

      Working...
      X