Build of 3 Speed Friction Drive

Discussion in 'Friction Drive' started by Lee_K, Oct 31, 2012.

  1. Lee_K

    Lee_K Member

    Winter is just about here and its too cold for me to do much riding so I think I will fill my time by building another bike. I started planning this project a few months ago and was working on rack mount with chain drive. A few guys have had positive things to say about friction drives and they are making me want to give that a try.

    I can't resist adding extra complication so I will be building the drive roller around a 3 speed sturmey archer hub. I bought the bike at walmart about 5 years ago, its a 3 speed with coaster brake. Here's photos of the SA roller and the bike. More photos will be coming as I make parts.

    [​IMG];[​IMG]
     
    Last edited by a moderator: Dec 15, 2015
    happycheapskate likes this.

  2. BigBlue

    BigBlue Active Member

    Interesting! Look forward to more pictures and updates.

    Chris
    AKA: BigBlue
     
  3. Lee_K

    Lee_K Member

    A few more comments on the drive roller. It's made from a urethane scooter wheel which is epoxied to the SA hub. It was then machined in a lathe to 3.7 inch diameter.

    I see two advantages of friction drive--simplicity and reliability. And three disadvantages--only one gear, slip, tire problems. The SA hub gives me 3 gears, the large dia urethane roller will give good traction to the tire without deforming it and reducing the flex that causes tire issues. But I have to give up simplicity to get the 3 gears and large roller, I do not intend to give up reliability.

    The CAD image shows how I expect it to work, two belt drives and a jackshaft.

    I am currently working on the engine pulley and bell housing.

    [​IMG]
     
    Last edited by a moderator: Dec 15, 2015
  4. Richard H.

    Richard H. Member

    Hi Lee, I remember your other project so no doubt you possess the skills and resourcefulness to achieve desired results. I wonder though after going to all the work you'll still end up with the less than optimum engagement that is inherent in the nature of all friction drives, IE: they slip and profusely so when lubricity is added in the equation. Not sure of your riding habits but obviously much of this is climate related. Also, you don't mention the engine choice but it seems like you would expect some not insignificant power loss with double reduction to the rear wheel.

    Don't get me wrong, not meaning to come off as negative. For all the pluses that direct friction drive can offer like simplicity and ease of install, yours is a quite complex solution with 4 pulleys, 2 belts and a jackshaft. Just curious because of mention in the opening post your initial thought of using chain. Wouldn't the system you're devising be better suited to use chain or belt? For that matter, I can see it would probably be a fairly straight forward conversion to chain or belt at a latter point if you don't care for the results with FD.
     
  5. Lee_K

    Lee_K Member

    Richard--those are all real good observations. I have gotten all the kinks worked out of my first MAB and have ridden it over 1000 miles. This project is a bit of an experiment.

    I’m using another robin-subaru 35cc engine, the same as my other bike so I will have a good use for the engine if this project fizzles out.

    I like belt drives because they are quite, I believe they are better than chains for these short center distances (5.75“ and 6.50“), and I can build them without idlers. It’s my guess that the power loss at the roller is much greater than a good belt drive, I’m prepared to accept these inefficiencies.

    I actually like the complexity because it makes it more challenging to build. Stay tuned because there will be even more weird stuff coming. And you’re right, I can always convert to chain drive to the wheel if I don’t like the end results.

    I hope this explains my thinking.
     
  6. darwin

    darwin Well-Known Member

    Interesting and complicated.......good luck. Any pics of your 1st build? Remember its a bicycle, honda 50cc metro in good condition/low milage will run you just $1000. Keep us informed with pics.
     
  7. Lee_K

    Lee_K Member

    Last edited by a moderator: Dec 15, 2015
  8. Lee_K

    Lee_K Member

    I won't be using the centrifugal clutch, I have two socket cap screws and rubber grommets that will go where the clutch used to be mounted. I just finished the engine pulley, it rides on two skate bearings and will be mounted to a bell housing. The back side of the pulley has two slots which will be driven by the rubber grommets. When I get the bell housing done and a photo this will make more sense.
    [​IMG]
     
    Last edited by a moderator: Dec 15, 2015
  9. Lee_K

    Lee_K Member

    Here's a photo of the bell housing. Now it's on to the frame and jackshaft which will take at least a week. I will post again when those parts are done. Thanks for following along.
    [​IMG]
     
    Last edited by a moderator: Dec 15, 2015
  10. Lee_K

    Lee_K Member

    Just finished the jackshaft, the pulleys, and enough of the frame to fit them together. The pulley ratios, sturmey-archer ratios, and roller size calculate to equivalent engine mounted rollers of 0.77, 1.03, and 1.38 diameters for the three gears. Next, I will be working on a starter mechanism.
    [​IMG]
     
  11. BchCruizer

    BchCruizer Banned

    Thats really cool looking. But there's def. to much going on there to be reliable. Wood pulley's? Dont get termites! Cool idea though. Hope it does work out great for ya!
     
  12. BigBlue

    BigBlue Active Member

    Looking good!

    Chris
    AKA: BigBlue
     
  13. Lee_K

    Lee_K Member

    It can be both complex and reliable. If I get this to work, I expect I can tweak reliability into it.

    I used this type of belt drive before and it works really good. The small aluminum pulley is grooved to match the 4 belt ribs, the larger wood pulley has a smooth surface and is made over size and then machined smaller in steps to get a proper fit with no idler. The rubber belt ribs compress to allow for tolerance. This is my first try at making the small grooved pulley from wood, that might have to be replaced with aluminum.

    This project is highly experimental, if it flops I will try something else.
     
  14. Lee_K

    Lee_K Member

    I mounted the drive mechanism to the bike and added a starting system. The attached 10 second video shows how the starter works. There is a brake lever on the handlebar which is connected to the starter roller.

    In the video I first show how the bike can be pedaled with the motor off. The tape on the jackshaft and motor pulley shows these are not turning.

    Then I actuate the the stater a few times to show how the roller is pulled into contact with drive roller and the jackshaft roller.

    Then I engage the stater and pedal to show how the engine is started. The jackshaft and engine both start to spin.

    I need a few more days to make up control cables and cobble up a gas tank, then can give it a try.
    [​IMG]

     
    Last edited by a moderator: Dec 15, 2015
  15. BigBlue

    BigBlue Active Member

    Nice! Keep up the good work.

    Chris
    AKA: BigBlue
     
  16. Happy Valley

    Happy Valley Active Member

    That's just a marvel Lee, I'm sure with anyone of lesser craftsmanship or having less mechanical ability the results would be far different. I'm curious to know how it runs on the road and your impressions over the long haul.
     
    Last edited: Nov 25, 2012
  17. Josh Moon

    Josh Moon Member

    That is pretty sweet!
     
  18. Lee_K

    Lee_K Member

    A few days ago, I took the bike outside for it's first test. It started and ran good for about two blocks, then started making rattling noises like something bad was happening to the engine. The problem was the rubber grommets that drive the engine pulley got wiped out. Post #8 shows these parts. I made some corrections and eliminated the rubber parts.

    Today, I rode it about two miles and everything works. All three gears work and the ratios seem right. I did have problems with operating the starter control. The starter lever needs to be squeezed real hard to get the starter roller to not slip, just needs a little more leverage.

    Next I will be working on a permanent gas tank and I am going to try to make my own larger and quieter muffler.
    [​IMG]
     
    Last edited by a moderator: Dec 15, 2015
  19. graucho

    graucho Active Member

    The good ole USA needs a bunch more Lee_K's. You know, like it used to be when the country wasn't sitting on their butt's watching reality shows letting their brains turing to mush. (nobody on this forum of course)
    When we were experimenting, creating, inventing, prototyping and manufacturing. Way to go Lee. Keep it up buddy.
     
    happycheapskate likes this.
  20. rawly old

    rawly old Member

    Well, Lee
    All I can say is don't give up. Life's an ongoing battle of trial & error.
    No matter how well some of my put-togethers work, I'm always thinking
    there's gotta be a way to make it better.....and sometimes worse.:ack2:
     
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