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9th May 2020, 11:19 AM
#11
Re: Oh dear, someone failed to do the last check
#7 John, if I recall the crane had a SWL of 5000 tonnes, re your 75% test overload, would mean a test load of 8750 tonnes, would that be correct, (or am I reading it wrong) rules may be different on specialist cranes for calculating stresses and overloads with all this computer modelling, so either the computer got it wrong, (or input = output = human error) or some key-bolts were not in place. The jib would have different SWL for different duties (single lift as opposed to cycle duty). I sold grabs and cranes and cannot count the times I have had to tell contractors a 100 tonne crane will not lift 100 tonnes at and radii and on cycle duties it will only lift 12/14 tonnes grab and contents and should not be jibbed under 45 degrees. We designed and built grabs to lift up to 4000 tonnes (salvage) so had to be aware of crane requirements and that grab required a sheerleg of 10/12000 lift capacity with a near vertical lift. About 90% of grabs were custom built, but we kept a stock of 100/120 grabs of all descriptions, which could go out as standard or converted to, self dump, pull off dump, radio controlled, motorised radio controlled, hydraulic, electro hydraulic, underwater self propelled hydraulic, screw operated, 1,2,3,4, wire operated, anything was possible
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13th May 2020, 09:22 AM
#12
Re: Oh dear, someone failed to do the last check
Few red faces in the design office I think.
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14th May 2020, 06:02 AM
#13
Re: Oh dear, someone failed to do the last check
But any test, just like the Road Worthy or any other such is only valid at that point in time.
Yes fine at the time of the test, but next day something goes wrong and you no longer have an effective machine.
Happy daze John in Oz.
Life is too short to blend in.
John Strange R737787
World Traveller
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20th May 2020, 08:54 PM
#14
Re: Oh dear, someone failed to do the last check
seems the test load was to be 5500 tonnes, but the hook with a SWL of 5000 tonnes failed at 2600 tonnes, there is going to be one long court battle and only the lawyers will be the winners, as even if the hook failed at 2600 tonnes it shouldn't have caused the jib to buckle as it did, the jib should have been able to absorb the shockload at half its SWL. The crane builders and the hook builders need each other as they are both specialists in their respective fields, but the lawyers will still get rich.
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