Crane flips, operator bails out

[Rock knocker]

Question 19. The answers are supplied from a link on the sample test

ttp://www.nccco.org/nccco/certification-programs/mobile-crane-operator/written-exam/sample-test-questions/questions

 

[Shield Arc]

I've worked with those little truck cranes before. Company would not allow us to make a pick past the front set of out riggers. And never over the cab of the truck! I hate working with truck cranes. Everything depends on the out rigger pad. I've been in situations where we drove pile to place the out rigger pads on. Much safer that way.
I feel more comfortable working with these! This crane is rated at 50-tons at 285-feet radius.:cool2:

 

[Rock knocker]

Blame Shield Arc for Seattle Trafficgeddon? :laughing::laughing::laughing:

I-90 closures ahead: Eastside drivers might want to just stay home | Local News | The Seattle Times

 

[Shield Arc]

No, no, no! I had nothing to do with the East Channel bridge! But I did drive all the pile from the East Channel Bridge to 405 for the elevated section of I-90. So if that falls down you'll know who to blame.:laughing:
Also drove a good 1/4 of the pile through Ebey slough for Highway 2.

 

[Rock knocker]

I would have to disagree with the "counterweight" theory. While the cab and engine will act as a counterweight, the long moment arm of the front of the crane far exceeds the counterweight effect. It becomes a very long stabilizer and is far better at resisting overturning.

In other words you have to push the cab into the ground to overturn it just as you would have to push a stabilizer into the ground on a side lift.

Finally found it, my charts from long ago for a 70T Grove hydraulic truck crane. If you compare ratings, you'll see that the ratings over the rear are all structural limits, and are greater than the 360* tipping limits. Where both ratings are structural, they will be equal.

But operating over the rear puts the carriers engine into position as an additional counterweight, and allows the picking capacity to increase from a tipping to structurally limited load.