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Thread: Chain losing tension

  1. #11

    And you are?

    Carbon tub,

    Not worth to introduce yourself? Just a matter of courtesy. This is not a super market.
    Claude Rouelle
    OptimumG president
    Vehicle Dynamics & Race Car Engineering
    Training / Consulting / Simulation Software
    FS & FSAE design judge USA / Canada / UK / Germany / Spain / Italy / China / Brazil / Australia
    [url]www.optimumg.com[/u

  2. #12
    Senior Member
    Join Date
    Dec 2009
    Location
    PERTH, Western Australia
    Posts
    208
    He did in his first post, could have included a little more info (course/discipline etc) but the basics are there.

    CarbonTub, have you a photo of the diff/engine/chain area?
    ex-UWA Motorsport

    General team member 2013-15, Vehicle Dynamics Team Lead 2012
    Project Manager 2011, Powertrain minion 2009/10

  3. #13
    @Claude, I did introduce myself in the very first post. In case you missed it, I'm Prateek from Ashwa Racing (formula Student team of RV College of Engineering, Bangalore, India).

  4. #14

    Apologies

    Prateek

    My apologies. You DID introduce yourself in your first post. I am sorry.

    I am so used to people leaving a signature at the bottom of their post and I am so used to Indian guys not often introducing themselves that I assumed that you did not introduce itself. I assumed.... I should have checked and I didn't.
    That is an explanation but not an excuse. Again I apologize.

    Basically what I am trying to say is:
    - Nothing is rigid: The chain, the chassis, everything has some deflection resulting to acting forces and also temperature change, and there is often residual deflection.
    Therefore the slack that you can have in the chain. That is especially true for a new chain or for, other example, a new throttle cable. There is some kind of "bending in" needed procedure.
    Other illustration: When I was in F1 we learnt that we needed to calibrate the pushrod strain gauge only after either a few track laps or a few run on the 7 post rig.
    We could see that after a few "bedding in", the strain gauge did not show the same results as the one we got after a first calibration on a brand new pushrod.
    - Things are moving. That is a consequence of the previous consideration. How can you be sure that your engine and your diff are exactly, all the time, at the same relative position to each other? Can you exactly measured each cause and of the different compliance and residual compliance? I can't but I can measure the final results.

    Will you be at Formula Bharat? If so, we can discuss your questions and my comments in details. In just 1 week.
    Last edited by Claude Rouelle; 01-17-2018 at 07:55 AM.
    Claude Rouelle
    OptimumG president
    Vehicle Dynamics & Race Car Engineering
    Training / Consulting / Simulation Software
    FS & FSAE design judge USA / Canada / UK / Germany / Spain / Italy / China / Brazil / Australia
    [url]www.optimumg.com[/u

  5. #15
    https://www.youtube.com/watch?v=LdN27HzoyO4
    Like the song in that link, this discussion's missing something.

    1) How does a chain go from its new length to its service limit? If it's by yielding, wouldn't you see massive differences in chain life between drivers and between track surfaces, including some cases where the chain fails immediately and others where the chain life is indefinite? Wouldn't you see large variations in link length on a used chain? How much force would it take to reach a shear stress of 1000 MPa in the pin going through the chain, which is 4.4mm diameter?
    2) Hold a brand new chain sideways, next to a chain which is at the end of its life, so that they extend out like beams. What do you see? What does that tell you about the mechanism of failure? Why do you usually replace the aluminum sprockets at the same time as the steel chain?
    3) Under the maximum load you calculate the chain is under during acceleration or braking, how much does your chain deflect? (NOTE: Think CAREFULLY about the safety precautions when you test this, you'll apply several kN and things can go flying if they aren't anchored properly)
    4) Why do you need any slack at all in a chaindrive? Why wouldn't you just slide the engine forward, or differential back, until it's "tight" and clamp it down in that position?
    Charles Kaneb
    Magna International
    FSAE Lincoln Design Judge - Frame/Body/Link judging area. Not a professional vehicle dynamicist.

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