Advice on scope setup on hyd sytems

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muttnjeff
OneWave
OneWave
Posts: 49
Joined: Tue Jul 21, 2020 7:19 pm

Advice on scope setup on hyd sytems

Post by muttnjeff »

Looking for tips/tricks and any other info on scope settings for reading hyd pressures.

The machine is a Miller 6300 front boom sprayer.

Keeps failing a priority valve inner seal backing ring which affects the steering phase as this is a 4wheel steer machine.

Planning on monitoring the steering circuit and suspension circuit in addition to charge pressure.

All advice is appreciated.

ben.martins
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Joined: Tue May 16, 2017 1:02 pm

Re: Advice on scope setup on hyd sytems

Post by ben.martins »

Hi muttnjeff,

I think the plan to measure the steering priority circuit is essential but I would want to include the other side of the priority valve, which will supply oil to the other circuits that the steering circuit doesn't need.

Seals that are failing are often caused by unwanted pressure spikes within the hydraulic circuit which using the two measuring points above may give some direction. The other place where pressure spikes can occur is direct from the pump itself. In an ideal world have these 3 points measured would give the best overall capture but I know this isn't always possible.

Pressure spikes can sometimes be a pain to observe, especially with a digital gauge as they don't react quickly enough. This is where the trusty neeedle gauge can help but then you have no real way of recording this. With Pico and the WPS600C hydraulic pressure transducers we have the advantage of recording the pressure but also adding in a math channel called the Derivative, d/dx. This math channels shows you the rate of change of one channel to another which when looking at hydraulic pumps, is the change in pressure against time.

This math channel doesn't like a lot of noise and we actually state that you should use a lowpass filter with your math channel. For the below capture I've used the following math channel - lowpass(derivative(A),10).
Derivative of Pump Pressure.png
Hopefully from this you'll see the change based on the pressure increasing Whilst I expect there isn't a value to compare with this might just show little more about the system.

As always please stay safe around hydraulics. I know you are more than qualified to work on these machines but for anyone else, please make sure you have the correct training before diagnosing hydraulic circuits.

Hope this helps in someway and please keep us posted on your findings.

Kind regards

Ben

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