Torque Angle

  1. Hi

    Obviously the purpose of using a torque wrench is to tight a bolt to a specific tightens, but what i cant comprehend is the purpose of using a torque angle wheel ?

    Why are they used, is the torque wrench not enough ?
     
  2. jcsd
  3. I believe what you are referring to is a method of torqueing a fastener by tightening it until it is hand tight and then turning it X degrees farther. First I had heard of this method was torqueing a timing belt pulley on a Deutz industrial diesel. No keyways or anything, just tighten the heck out of it. In the case of the timing belt pulley there was a significant portion of the bolt between the head and the threads as they went into the end of the camshaft that was allowed to stretch. The actual foot-pounds spec was not mentioned.
     
  4. OmCheeto

    OmCheeto 2,153
    Gold Member
    2014 Award

    I just googled "torque angle wheel" and came up with only your post.

    Can you post a link to the device you are talking about?
     
  5. AlephZero

    AlephZero 7,298
    Science Advisor
    Homework Helper

    Try googling "torque angle wrench". For example
    http://www.eastwood.com/digital-electronic-torque-angle-wrench-3-8-drive.html

    Averagesupernova is right. The "traditional" style of torque wrench is not a very accurate way of setting the bolt load, because there is an unknown amount of torque being used to overcome friction when tightening the bolt, especially if you are rebuilding something and re-using the old parts.

    That was not too important for a "low tech" design where you could allow a large safety factor between the required load in the bolt and over-stressing it, to allow for a large range of friction force.

    That is no longer good enough for some purposes. so an "angle wrench" measures the angle the bolt head is turned through. That was not very practical until cheap electronic position measurement was available, but it can be now built into the handle of a normal-looking wrench, plus a digital readout of the torque (and audible signals when you reach the required values, etc) instead of the old scale-and-pointer method.

    FWIW for some applications, the bolts themselves have built-in force transducers, so you can check the bolt load during maintenance without the risk of over-tightening the bolt "just to check it isn't loose".
    http://www.strainsert.com/products/force-sensing-bolts-studs-general-product-information/
     
  6. OmCheeto

    OmCheeto 2,153
    Gold Member
    2014 Award

    Interesting. My only experience with such a thing has been when changing my oil filters. "Seat, then tighten 3/4 turn"

    This new concept does make sense.
    Smart bolts? :thumbs:

    My friend should have probably used those. He rebuilt a small block '68 Chevy engine last year. 15 seconds after he started the engine, he heard some knocking, then the pistons started flying, as he apparently hadn't properly torqued down the connecting rod bolts.

    Though he'd probably need bolts smart enough to shout at him; "Hey! Old dude! I sense that you've torqued down 31 of my brother bolts, but not me. What's the deal?"

    ----------------------
    writes down patent idea #8,532,081
     

  7. There you go
    http://images.hemmings.com/wp-content/uploads//2013/08/torqueanglegauge_700.jpg

    P.S

    There is a few videos about this on YouTube, but I still don't get the idea of it
     
  8. OmCheeto

    OmCheeto 2,153
    Gold Member
    2014 Award

    Aleph's explanation made a lot of sense to me.
    If I were to try and expand upon it, I'd probably screw it up.

    Oh what the hell. They can only ban me.

    Imagine you have two sets of nuts and bolts that you want to clamp something together with.
    One set is new, and all lubed up with motor oil.
    The other set, is old, dry, nicked, bent, and rusty.

    Now it's quite possible, that with the old set, you could reach the maximum torque limit even before the nut and bolt have started clamping down. So there, you would want to seat the pair, and then torque them down using the angle method, as the torque measurements might be extremely off.
     
  9. Well let's assume that this is in a case where you have dirty old bolts and using a cheep torque wrench, in this case you'll use a torque angle gauge to be on the safe side. But if a good shining torque wrench where used with new fresh bolts, would it be necessary to use the angle gauge ?
     
  10. That all depends on your application, and what accuracy of bolt preload is required.
     
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