Centrifugal clutch and related experiments.

Discussion in 'Transmission / Drivetrain' started by Frankenstein, Dec 13, 2016.

  1. Frankenstein

    Frankenstein Well-Known Member

    We have here a pretty standard centrifugal clutch kit, a few extras as far as grease fittings go. As Fabian knows his China girls and states quite clearly, lubrication is everything.
    1: clutch bell and bevel gear : crankshaft collar is currently installed.
    2: crankshaft collar
    3:bolt that holds the boot assembly and crankshaft collar on crankshaft.
    4: This is a heavy bearing that is part of the one-way bearing which allows pedal starts or even kick starts depending on design. It's really heavy duty, it might even mushroom the collar preventing disassembly,luckily it came with a puller tool which is not pictured.
    5: this is the retention spring for the one way bearing. It can be installed in several ways but only one spot is effective to keep proper pressure on the bearing, if not under enough pressure it will not work very effectively, and will slip as a pedal start us attempted, more on this later.
    6: Various brass fittings and matching taps, will construct better grease application later.
    7: simple junk drawer grease applicator in making.
    Here's a better look into the bell. The yellow circles indicate where a groove is cut into the metal to act as the float zone for a roller in a one-way bearing.
    The blue thing is your imagination making it look like a roller in the groove.

    You see all those tiny black/red spots that circle where the gear is pressed in from the other side. Those are open holes, grease can pass right through to the bearings and rolling surface while it's hot and steamy down there and all the hot gears grinding along eachother with all the lube flowing between them. Ahem.. Uh moving on.

    Sideways shot where the bearing rests in its grooves.
    And here one of it on that shaft. Few more poses for the 3d thinkers.

    Attached Files:

  2. Frankenstein

    Frankenstein Well-Known Member

    20161213_182437.jpg 20161213_182409.jpg 20161213_182437-1-1.jpg
    The image just above is an idea for some lube sinks, basically a small shallow groove cut into the surface and made smooth. If designed right they pull and push lube where it needs to go, think how tire tread cuts up fluids and pushes it out from under your wheels so you don't slide. An effective way to disperse grease or lubricants in a system and is a widely used idea in car transmissions when pressing fluid into small places.

    At low speeds it should work well.

    This is basically self explaining right here, I drill paths for grease in the bolt and tap it for those threads. The grease tube attachment will be used to grease the bearing and collar. When finished a soldered shut jet will behave as a plug.

    I know this will be a better way to apply lube to these parts, drilling a hole in the gear to alow you to grease is kinda odd.

    Drilling the bolt will alow fresh grease exactly where it should go, and provide a bit more convenient way to get these areas properly greased.

    Any questions just ask.
  3. CrazyDan

    CrazyDan Active Member

    Sounds oh so...sensual.
  4. Frankenstein

    Frankenstein Well-Known Member

    Yes I'm trying to be very accurate.
  5. darwin

    darwin Well-Known Member

    Good idea, do you remember seeing the bearings on certain wheels where you could grease a zerk and pack the bearings w/o removing the axle nut etc? Something like that would be ideal.
  6. Frankenstein

    Frankenstein Well-Known Member

    That would be perfect but the smallest zerk I can find that isn't made for nasa (aka not in my price range) is still too large for this bolt. This is why I'm cutting threads into it and making a custom grease fitting, talking of which..
    20161214_133435-1.jpg 20161214_133435-1-1-1.jpg
    Here is the bolt locked into the plate, in case anyone cares the thread size on these particular bolts including the thread on the small bevel gear bolt are the same as most skateboard and roller skate axle threads. I recognized the thread right away and used a nut from one of my older skates to secure it to the plate with washers.

    The second image is an idea of what's happening, the yellow bolt is drilled about 17mm deep from the top, then a hole in the side. The top portion in the head is drilled slightly larger, then tapped and a purple jet can be threaded in, securing the greaser to the bolt.

    Thumbnails of standard drilling practice to a depth of 17mm
    20161214_133819.jpg 20161214_143032.jpg 20161214_143109.jpg

    May as well drill my fittings while we're here and have a solid base to work on. This will make the resistance of the grease application lower and easier to do in general. All parts are drilled to max possible size without disrupting the integrity of the fittings.
    2016-12-14 14.41.03.jpg

    Switch to a larger bit and some extra oil and cut my pilot for my threads.
    20161214_145239.jpg 20161214_145356.jpg 20161214_150741.jpg

    A small Super magnet and a small metal rod are well adapted to removing metal shavings and chips without flooding your workpiece in oils and you can leave fixed to the work surface. Observe: 20161214_155112.jpg

    The butchered drill lets me hold the stationary back upright and vertical, which aligns the tap nicely, once threads begin cutting a few deep I swap to a plug from a taper tap. Only the chuck spins so I can steady the tap in the threads and feel my way deep into her nice and easy. Never managed to cross thread anything doing this, and I also use this to thread small 1.2mm holes too like this.

    Anyway moving on to next post:
  7. Frankenstein

    Frankenstein Well-Known Member

    Tapped m4 threads in bolt head.

    Obviously standard screw will thread in 20161214_160129.jpg

    Jet threaded in, little off center but I'm not building a rocketship today so no worries.
    20161214_155953.jpg 20161214_160009.jpg

    Coffee break.
  8. Frankenstein

    Frankenstein Well-Known Member

    Strapped and loaded.

    Drilled clean.

    2 videos quick look at thread smoothness and side hole drilled.

  9. Frankenstein

    Frankenstein Well-Known Member

    Screw that, this is some very tough hardened steel. The material is a good idea I'll state. The stainless clutch bell will rather quickly work harden. It will form a very nice working surface with the much harder steel.

    Behold my failure.

    OK so drilling this is not happening, I did cut grooves as planned on the surface of the crankshaft sleeve. This will act as a better distributor of grease in this appliances. I'd like to have done it better but for now I'll rotate the bell while greasing to get best spread.

    Tough and almost looks like the steel was milled so it pulled grease inward..its hard to say other than the manufacturer picked the right materials.

    OK so let's get back to that grease gun like thing.
  10. Frankenstein

    Frankenstein Well-Known Member

    This is the gun with the tip soldered to a brass fitting Yada Yada and to the bolt which has holes in it.

    This is after squeezing the trigger 5 times, pressed about a cc roughly. Easily enough to get grease everywhere it's needed. 20161220_231736.jpg
  11. CrazyDan

    CrazyDan Active Member

    Very nicely done. Looks like it's a perfect setup to keep it greased.
  12. Frankenstein

    Frankenstein Well-Known Member

    Actually what I said was wrong, the tip is soldered to the die cast pot metal that they use to make a carburetor.

    The nipple was the gas line hookup to an nt carb, I hacksawed the threaded portion out of the carb that the nipple threaded into. One of the fins for the intake snapped off so it was close to hitting the scrap bucket anyway. The metal soldered to it kinda reluctantly, think it was just taking a while for the Flux to break past the oxide layer. Once both parts were wetting nicely to the silver solder I took a flame and heated them up for 30 seconds (I found they both had high heat dissipation, the iron was having trouble keeping both hot enough to keep the solder flowing) and then sealed them together.

    This means the brass fitting on the green tube unscrews from the end of the gun, and the silver tip unscrews from the gun too, not important but I figured I'd mention it anyway.

    I saw some zerk fittings at Harbor freight, @darwin, I was thinking of retrofitting the input of that brass and tube fixture to have a zerk since they have them reasonably small. This would alow the grease gun with a normal end to be attached without screwing the gun onto the thread and rather just popping it on.
  13. Frankenstein

    Frankenstein Well-Known Member

    So studying the parts and cleaning them on close inspection we find the bearing ream is pretty rough looking, it has got the cutting burrs on most edges, seeing that this will be in contact with bearing contact surfaces I will clean it up with a file and then maybe polish. The slot nearest the file point has been touched up already with a file.

    20161221_203345-1.jpg 20161221_204149.jpg

    Studying it I'm finding that I'm becoming doubtful that @Fabian is correct in saying the area between the crankshaft sleeve and the internal smooth surface is a load bearing surface. The roller bearings make more sense to actually do ANY load bearing since they have the smallest space tolerance from the bell body to the shaft extention, especially under spring tension.
    Otherwise the bell is actually just sitting there not moving and only resting its weight on the spinning shaft. When the clutch engages the bell then the whole thing spins as a single unit and so it's not even playing part in taking the power load of the engine through the remainder of the drivetrain.

    Anyway, going to finish this filing and move to the next part of the game.
  14. darwin

    darwin Well-Known Member

    Cool, your definitely a wrench head! It's nice to have tools to do the job.
  15. Frankenstein

    Frankenstein Well-Known Member

    Thanks, even as a kid I was tinkering with toys and watches and clock parts and rc vehicles.

    The mid size motor hobby is just something I always liked, gained a nice tool collection just for odd jobs and then I realized how much more potential most tools have. All in the leverage you know.
  16. Frankenstein

    Frankenstein Well-Known Member

    Ok proof of the concept.