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Is This Measurement Method Accurate? 1

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CMT22

Mechanical
Aug 17, 2016
5
Hi all,
I’m attempting to measure dynamic loads on the pins and bushes at the indicated location on an excavator marked in blue.

I’m thinking of installing a pressure transducer in-between the hydraulic hoses at the location marked in green. The data will be transmitted to the cloud.

With the measured pressure and the dimensions of the hydraulic cylinder, I can calculate the loads on the pins and bushes over a period of time.

Can I get some second opinions regarding the expected accuracy of this method of measurement? Are there any sources of error that could render the data inaccurate?

I like this method because its minimally intrusive to the machine, which is important because the machine isn’t owned by us, therefore essential that it’s not interrupted in any way.

Thanks in advance for the help.
 
 https://files.engineering.com/getfile.aspx?folder=81d11402-5c8d-4bf5-822c-689379ba8e72&file=InkedEX5600-6_Image_LI.jpg
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Yes,
This is one of the easiest and only method of mapping the pressure values on field machine.
Mapping pressure values at rod end and cap end (2 transducers required)can help you to understand loading conditions in better way.

Would like to understand the purpose of this analysis.
 
Please just post directly into your post. (Camera picture with Image word)

InkedEX5600-6_Image_LI_a6pw5n.jpg




Keith Cress
kcress -
 
The problem is you're using an indirect method of calculating the pin forces, so it depends on what you are trying to work out.
Validating design calcs? Maybe OK.
Trying to reverse engineer pin failures? Maybe not OK.

Most likely you won't pick up any shock loading on the pins due to damping effects in the hydraulic system - if they're important for you or not.

The better approach is an embedded strain gauge inside one of the pins, that will give you a direct measurement. Takes a bit more installation work but can make the quality of the results better.

I've seen issues in the past where we were breaking pins and cylinders in one application, hydraulic measurements weren't to bad but the measurements made on the pin were pretty illuminating as to the cause of the problem.
 
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