bucket digging force versus breakout force

[mrdenial]

Are these two values supposed to be the same? I notice cat uses digging force and komatsu uses breakout force.

I'm trying to compare apples to apples on the terminology...But I realize that between vendors even apples to apples isn't going to really compare.

Thanks,
Daniel

[Tigerotor77W]

They are supposed to be the same thing, but I'm honestly not sure how manufacturers rate their equipment in this regard.

[Wulf]

For excavators there is maximum crowd force (arm) and max digging force (bucket) The way they are measured/determined should be the same. Maybe the manufacturers are only publishing where they have an advantage?

If one has a significant difference then its either done through hyd pressure, cylinder bore/rod size or geometry.

For machine performance also check out lifting force over front and side, drawbar pull and drawbar pull/weight ratio, swing power.

[Wulf]

There are also two ways of rating the above (SAE or ISO) which will skew the numbers. ISO numbers will be a bit higher.

[Wolf]

How to you figure out how much bucket force you need to wreck a particular kind of structure?

[CEwriter]

I can't tell you exactly how they measure these forces either, but I'm pretty sure the guys at Spec Check know. I'll try to get an answer for you.

By the way, at www.spec-check.com, if you subscribe to Xpanded Specs you can easily compare any excavator models by bucket breakout force or arm-crowd force or any number of other specifications. The guys at Spec Check are pretty good at making sure you have an apples to apples comparison.

A couple of words of caution:

1) If you're comparing arm-crowd forces, make sure the arms (sticks) are about the same length. All other things being equal, a longer stick will generate less digging force.

2) If you're comparing bucket-digging forces, make sure the buckets are about the same size. Similar physics apply.

ADios,

L

[CEwriter]

OK, so here is what the good engineering types at Spec Check have to say about excavator digging forces:

"SAE J1179 defines hydraulic excavator and backhoe digging forces. Here, the location for measurement is at the 'outermost cutting point,' usually the tip of the tooth. The 'maximum bucket tangential force' is measured and published separately from the 'maximum arm/dipperstick force.' Bucket and arm may be positioned wherever maximum forces occur.

"For a telescoping boom such as found on Gradall or Badger, 'maximum telescoping boom crowd force' is the digging force generated by the telescoping boom cylinder acting on a line parallel to the boom. It is independent of bucket position. This definition applies to telescoping booms only, not extendable arms/dippersticks.

"A complication with excavators comes from the International Standards Organization (ISO) with a strong European influence. ISO 6015 places the location for measurement at the cutting edge near the base of the tooth. This causes greater forces to be calculated for the same arm or bucket because of shorter distances to the pin. Some excavator manufacturers publish both SAE and ISO forces. Spec Check has separate fields for SAE and ISO.

"On excavators, bucket breakout forces usually remain the same, regardless of arm length, as long as the bucket cylinders and pressures remain the same. Arm crowd force will of course change inversely with arm length."

There you have it.

To see an illustration of the 'maximum bucket tangential force,' go to

http://www.constructionequipment.com/article/CA428633.html

and scroll down just pass the fuzzy and indistinct bar graph on the right. There's an illustration of a bucket there that shows what "bucket tangential force" is.

Hope this helps.

ADios