Page 2 of 2 FirstFirst 12
Results 16 to 20 of 20
  1. #16
    Join Date
    Jun 2011
    Location
    Australia east coast
    Age
    71
    Posts
    2,713

    Default

    Quote Originally Posted by Michael G View Post
    The other alternative is that without that 'spring',vibration will allow the joint to loosen.

    Michael
    Which is why I use a lot of Loctite and Nylocks.....

    PDW

  2. #17
    Join Date
    Feb 2003
    Location
    formerly from Sydney (north of The Harbour), NSW, Oz
    Age
    68
    Posts
    306

    Default

    Quote Originally Posted by China View Post
    This is a bit off topic, Ian does that mean that that mounting a jockey wheel bracket to a trailer with high tensile bolts into mild steel is fundamentally wrong
    given that it's 40 years since I last did any work using bolted joints, what I recall could be wrong

    high tensile bolted joints are not really "bolted together". When a HT bolt is "done up" it is streteched along its length. The elastic properties of the steel convert this stretching into a clamping force that acts to increase the friction between the plates being bolted together. It is this friction between the plates that gives the joint its strength, not the properties of the bolt itself. A HT bolted joint fails when the joined plates move (slip) relative to each other. I don't recall how much strength the bolt by itself added to the joint, but do recall that if the bolts weren't fully tightened (i.e. stretched) the bolts would sheer (i.e. break) relatively easily.

    a joint bolted with mild steel bolts gets its strength from the toughness of the shank of the bolt and the properties of the metal plates. The joint fails when the bolt bends too much or the plate buckles against the shank of the bolt. The primary purpose of the nut on a mild steel bolt is to stop the bolt itself falling out of the bolt hole. A mild steel bolt will hold two pieces together, but will not clamp them hard enough that friction between the pieces becomes a significant factor.

    placing a mild steel nut on a HT bolt is a No-No because the threads in the mild steel nut are too weak to allow the bolt to be correctly torqued.

    I also recall that a mild steel bolt and HT nut are also a No-No, but I don't remember why.



    looking at an engine or trailer component, for a HT bolt to be effective, the threaded part of the casting or trailer would need to be the right strength, otherwise the HT bolt can not be tightened to the correct torque.


    You can look up recommended tightening torques here http://www.westcoastfasteners.com.au...20handbook.pdf
    On first reading it looks as though a properly tightened HT bolt needs 5x the tightening torque of a mild steel bolt.
    regards from Canmore

    ian

  3. #18
    Join Date
    Dec 2005
    Location
    South Australia
    Posts
    1,656

    Default

    Thanks for the replies, just about to repair a mates trailer and he was fairly insistent that HT bolts were the go, I think I will stickwith the mild steel and explain that if you drive off with the jockey wheel down even with HT bolts it is still going to wreck everything

  4. #19
    Join Date
    Jul 2008
    Location
    near Warragul, Victoria
    Posts
    3,718

    Default

    When buying 4140 don't buy the soft annealed stuff. Think its called black or hot rolled .

  5. #20
    Join Date
    Jun 2007
    Location
    sydney ( st marys )
    Age
    64
    Posts
    4,887

    Default

    Why?

Page 2 of 2 FirstFirst 12

Similar Threads

  1. M12 grade 8.8 "high tensile" bolts
    By bob ward in forum METALWORK GENERAL
    Replies: 8
    Last Post: 23rd Feb 2015, 02:51 AM
  2. Replies: 3
    Last Post: 25th Jun 2014, 12:44 PM
  3. HIGH TENSILE BOLTS Vs MILD BOLTS.
    By chambezio in forum METALWORK GENERAL
    Replies: 13
    Last Post: 3rd Jan 2014, 08:25 PM
  4. Cuting High speed steel??
    By iron bark in forum METALWORK GENERAL
    Replies: 29
    Last Post: 26th Jun 2013, 03:01 AM
  5. welding high tensile chain??
    By Mathuranatha in forum WELDING
    Replies: 14
    Last Post: 17th Jul 2009, 09:59 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •