Excavator Maximum Operating Ground Bearing Pressure

[bpiermat]

Does anybody have a rule of thumb for the maximum reaction for a large excavator? Put the entire dead plus pick on one point or on one track? Other ideas?

Thx,

Ben

 

[JAE]

Usually the excavator manufacturer has wheel/tread load reactions that they provide.

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[bpiermat]

Thanks JAE, yes the manufacturer provides ground bearing pressures.

However it is often not clear if those values include the operating pressure. For cranes, these maximums are calculated, however, for excavator it is not as clear.

 

[JAE]

We've seen documents where they show various angles and elevations of the boom arm with resulting track pressures or wheel loads at each corner.
I believe these are with maximum payload at each position.

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[bpiermat]

Thanks I have not been privy to such info, yet...

 

[Lomarandil]

Are you considering ground pressure reaction, or are you on a structure?

I've dealt with this issue a lot. I haven't seen manufacturers provide track reactions from excavators picking a load per se, but they sometimes will provide information for operation with a given size bucket for earthwork. You can often develop a pressure distribution that satisfies statics based on those reactions, the excavator geometry, and some extrapolation. But it's a lot of work (and approximate at that). Be careful about your assumptions regarding track bearing length especially.

Rules of thumb, for excavators working over the side, I've seen as much as 90% of the total excavator + pick weight on one track. Working over the front, I've seen up to 60% of the track length "lift off" -- both within the operating limits of the machine.

You might also factor in how much you trust the equipment operators to stay within the posted limits of the machine.

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