Failure of our 15 ton crane

[Mahk_Adams]

This is the capacity chart for a 30 ton National crane with a 105 foot boom, single part line, full span outriggers, and no jib.

Again the shaded areas are structurally (not stability) limited. When I first started operating this crane and looking at the charts I was surprised to see that the vast majority of this chart is structurally limited.

 

[tod_k]

Thanks Mahk. I'm assuming with the jib on the 15 ton, they were reaching for distance and not hieght. As the boom goes down you start to go into "tip" since they were taking out wood I'm assuming they radius was lower for distance?

 

[Lumberjack]

The heavy black line that zig zigs across the crane chart is where the chart goes from structural (above) to stability (below) failures.

The only time I have swung a jib on a crane that size is for height, their boom lengths are quite limited, and rightly so.

 

[Mahk_Adams]

[ QUOTE ]
The heavy black line that zig zigs across the crane chart is where the chart goes from structural (above) to stability (below) failures.


[/ QUOTE ]

Are you reffering to the chart for the two different jibs (the first attachment)? There may appear to be a zig-zag in that chart:

The 27 foot jib is structurally limited from a 30 foot to a 45 foot radius. It is stability limited from a 50 foot to a 90 foot radius.

The 48 foot jib is structurally limited from a 35 foot to a 70 foot radius. It is stability limited from a 75 foot to a 95 foot radius.


The chart for the main (105 foot) boom, however, doesn't have that pattern. The main boom is structurally limited for most of the chart. The few exceptions are: 60 foot radius with a 75 foot boom; 70 foot to 80 foot radius with a 90 foot boom; and 75 foot to 90 foot radius with a 105 foot boom.

Also, just to be clear, this chart is <u>ONLY</u> for this crane. These numbers can't be used for any other configuation of boom, truck, or chassis.

 

[mdvaden]

Do you folks that use cranes use up to the "max" capabilities? Or do you have a rule-of-thumb like "80% of the chart is the limit"?