Cribbing under crane outrigger feet or chock feet

[trivedi123]

I need at least3'x3' cribbing under outrigger pad to transfer the load to supporting slab
Question is if feet has rubber (with ribs like car tires) pads as load transferring surface, the damping can reduce impact load or the cribbing requirements?
Thanks for help.

 

[Lomarandil]

Crane support loads are not significantly dynamic. With a good operator, there should be no or negligible impact while the crane is stationary and operating.

As such, the cribbing requirements would not decrease.



----
The name is a long story -- just call me Lo.

 

[racookpe1978]

On the other hand, if the ribs were pointed down (under the square 3x3 foot pad), they would compress a softer ground or dirt until sufficient area were resisting compression forces under each of the 4x cranes pads. If large gravel or asphalt or concrete, you'd expect less compression of the surface, but the ribs would compress.

Having ribs under the pads (facing down) would essentially reduce the initial contact area by 1/2 the pad nominal size.

 

[ornerynorsk]

It's the crane outrigger pads and not the cribbing that has the rubber ribbed surface, is that correct? I've been in a few heavy lifts with injection mold machines, and honestly I've never seen cribbing pads with rubber surfaces. This should not affect your cribbing surface as it relates to the slab, the pads are already sized with compression of any elastomeric material factored in to the crane capacity. The operator will load the outriggers prior to lift, likely enough that the undercarriage and chassis of the crane will no longer be load bearing through to the road tires.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[chamfer strip]

My thoughts would be to still use the required cribbing area and do not decrease due to rubber pads. The rubber pads are just for decreasing vibration and prevent damage to surfaces.

 

[trivedi123]

I am going to keep cribbing for the job.
Thanks for all support and clarification.