Extending boom while under load.

[AM424]

Hello. I am looking into a unique lifting situation and do not have much experience with mobile cranes, so I am hoping to get some insight here.

We are lifting a 23T test article into position within a high bay. Our over head bridge crane is only rated to 20T, so we can't use it for this lift. We do have a 70ft tall roll up door that has an area to stage a mobile crane outside the building and reach in. The test customer would like us to evaluate using a mobile crane, staged outside the building to lift and place their test article. The main issue with this plan is that the boom can not reach the test stand at the length required for the initial pick, and the roof is too low to extend the boom long enough for this. The test customer thinks we can just lift their equipment from the pick up point, get enough clearance off the floor to tilt the boom down, extend the boom so that the test article is over the stand, and then lower the test article.

They have identified a crane that can handle the loads at those operating radii, but the problem I am having is finding a crane that can telescope the boom out while under that load. From my digging, it seems like the boom is telescoped out and then pinned into place before loading. Is this strictly the case? Are there any cranes that handle this type of operation?

Thanks for any info or advice!

-AM

 

[funwithfuel]

You want a constant power crane vs a pin and latch.

 

[funwithfuel]

However, i don't see you extending out that far while using boom for reach. You need more height or you need to get the crane inside the building.

 

[cranesafety]

Our over head bridge crane is only rated to 20T, so we can't use it for this lift.

Why not use the overhead crane and do a Planned Engineered Lift? The 23T load (46,000lb.) is within the allowable 125% (50,000lbs.) of the 20T crane load rating. It appears this load will only be handled twice, setting it in the test stand and then removing it from the test stand, also meeting the standard limiting these lifts to two (2) within a continuous 12 month period.

 

[crane operator]

There's not enough info here to give you a straight answer. How close the pad is to the crane, how tall the building is inside the door. How big the item to be tested is in relation to the pad and building, etc. Will item be infront of the crane and scoped out. Coming off a truck. Already in the building, etc. I don't know if you can lift most of it with your overhead, and have a second small crane to take the rest of the weight?

As far as a mobile- Pin and latch booms can telescope under load. Its way easier to do with a full power boom.

There is a limit of what can be telescoped, and it typically depends on variable factors- grease on boom, temp. boom angle while telescoping, etc.

If you don't have the equipment anyway, which it sounds like you don't, the best answer is to call your local crane rental company. They know what they have, and what its capable of doing. And usually, if their equipment won't do it, they will know who you need to call to get it done.

There are cranes capable of scoping 23tons. I just don't know if you have room for it. Your local rental guy should be able to tell you after looking at it.

 

[Tyler d4c]

Why not use the overhead crane and do a Planned Engineered Lift? The 23T load (46,000lb.) is within the allowable 125% (50,000lbs.) of the 20T crane load rating. It appears this load will only be handled twice, setting it in the test stand and then removing it from the test stand, also meeting the standard limiting these lifts to two (2) within a continuous 12 month period.

So I'm not the only one that is going to tell the boss to come back in a hour....

 

[cranesafety]

So I'm not the only one that is going to tell the boss to come back in a hour....

This is actually a common occurrence with overhead cranes, just need to follow all procedures as per ASME B30.2, Section 2-3.4: Planned Engineered Lifts.

 

[Tyler d4c]

This is actually a common occurrence with overhead cranes, just need to follow all procedures as per ASME B30.2, Section 2-3.4: Planned Engineered Lifts.

Sounds like the proper way but I was quoting the "it needs done and done now"