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Old 03-17-2010, 01:53 PM
Tigerotor77W Tigerotor77W is offline
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Location: Charleston, SC
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Definition of breakout force, ROC, force to tip...

Question: is there anyone in the Illinois (central) or Michigan (near Detroit metropolitan) areas that'd be willing to work with me on a video or a bunch of photographs demonstrating how these things are related but distinct? I'd love to try to explain this, because there are recurring questions on here and the issue never seems to go away. I wouldn't be able to work on this until the summer -- I have another project in the meantime -- but I'd be happy to do it eventually.

Tipping load and ROC are standardized measures. The tipping load is the load at a prescribed bucket's load center that causes the machine to tip when the lift arms are at maximum reach. At different lift heights, the machine will tip at different loads, so the ROC and published tipping load are accurate only when the lift arms are at max reach.

Breakout force: a huge discussion in and of itself. A few people have posted elaborate discussions on this already.

Weight (force) to tip a machine: this is not a standardized measure because each lift height will have a corresponding amount of weight that will cause the machine to tip. With the arms all the way down, it will take a LOT of weight for the machine to tip; this is obvious because the machine feels more stable with the arms down (especially with a heavy load). At max height, the machine feels wobbly, and a considerably smaller load will cause the machine to tip.
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Old 03-17-2010, 07:58 PM
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stuvecorp stuvecorp is offline
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I'm probably too far north (unless you are heading to the Twin Cities) but would be welcome to stop in and use the Case, Mustang or ASL.
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Old 03-17-2010, 09:23 PM
Tigerotor77W Tigerotor77W is offline
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Thanks. I'll keep it in mind if I get a chance to work on this in the summer.
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Old 03-18-2010, 04:17 PM
tallrick tallrick is offline
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I did a project like this for my applied mechanics course for the engineering program over 20 years ago. The idea was to calculate the forces within a system using differential equations. Then transducers were attached to compare the results of deformation of the structure, and the moments of force at each pivot. I was quite shocked at how many newtons of force were needed to make a Bobcat 843 work. The radial lift skid steer has its maximum lifting force when the hydraulic ram moves the farthest for a given constant of vertical bucket lift. I was also surprised to find that the tipping load is lowest when the bucket is at operator level. Breakout force is also different at bucket angles. The last measurement was of the shear force at the tires when turning. That too is highly dependent on load amount and load balance.
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Old 03-18-2010, 06:17 PM
Tigerotor77W Tigerotor77W is offline
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Quote:
Originally Posted by tallrick View Post
II was also surprised to find that the tipping load is lowest when the bucket is at operator level.
Sounds like an awesome project! Would be so nice to publish those results somehow.

I quoted the statement above because it's true only for radial lift machines. Vertical lift machines will likely be different (especially for Deere and NH).
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