Thursday, 21 June 2012

Lifting

Lifting
Lifting
Lifting using Accessories

Calculation of Load

    There are only two types of load to be lifted
    • Known- there must be a Certificate of Weight or a Guaranteed Weight name plate attached.
    • Estimated- Any other weight. When doing lift calculations 50% must be added to estimated weight
    Note that in addition to the load itself additional factors such as ground effect e.g stiction and dynamic loading effects of lifting with relative motion between crane mount and load platform must be taken into account

Safe Working Loads

For a straight vertical lift the maximum lift weight is the Safe Working Load (SWL) of the lifting accessory
For a lift using an accessory with two legs or two matched pairs used at angles up to 45o from vertical ( i.e. non vertical to 90o included) then the maximum SWL is 1.4 (normally rounded up to 1.5) times the SWL in each leg e.g. the maximum lift for two matched 5 tonne strops is 7.4 tonnes

The maximum included angle is 90o, no lift should take place with angles greater than this.
For 3 or more piece lifting accessories of 3 or more identical lifting accessories used at angles up to 45o from vertical then the maximum Lift is 2.1 times the SWL or each leg. e.g the maximum lift weight of four matched 5 tonne strops is 10.5 tonnes

The maximum included angle is 90o

Note

    • For lifting accessories such as Multileg chain slings (�Brothers�), the SWL takes in to account that may be used at angles up to 45o and therefore the maximum lift weight would be the SWL of each leg times the number of legs ( or stated Total Lift) although this should be clear stated on Test Certificate.
    • The reduction in capability also applies to Shackles used when used in non vertical Lifts ( Dee Shackles must only be used in vertical lifts)
    • The reduction in capability also applies to Chain blocks, lever hoists which are in use.
    • For non uniform shaped loads special consideration has to be given to the Centre of Gravity and possible localised overloading.

3 comments:

  1. Impressive explanatory post with images, happy to found this post. I found some other posts about lifting patterns but those were not fit for proper explanations. It is visually easy for me to understand what you write as I am a visual person. Like to have a tour of your blog’s other posts.
    Lifting Chains

    ReplyDelete
    Replies
    1. I am the author of most of the work on your website against which you are making financial gain. If you do not gain permission or remove it I will take further action. My site is non-commercial, I note you have placed content from marinediesels.info which is a commercial site, you are in breach of his copyright and as such ne may not be as generous in allowing you time to remove his work before taking further action.
      brian

      Delete
  2. I am the author of most of the work on your website against which you are making financial gain. If you do not gain permission or remove it I will take further action. My site is non-commercial, I note you have placed content from marinediesels.info which is a commercial site, you are in breach of his copyright and as such ne may not be as generous in allowing you time to remove his work before taking further action.
    brian

    ReplyDelete