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dig-dug-dan

Hydraulic relief

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Another annoying problem with the crushers

 

As a bit of background, the jaws in these things is computer controlled.,its basically a hydraulic  ram that goes back and forth attached to a crushing jaw.

The clever part comes with the computer, where is firstly will always fully open itself when you first press the button, then it comes fully forward until it reaches max pressure, then an electronic pressure switch send a signal to the computer to tell the ceetop valve to change direction. It then comes half way back, before fully forward again, then fully back.

Now the problem. And this is a design problem as it happens with all my machines.

Very occasionally, the computer doesnt get a signal, or it just decides to ignore it, to change direction. The ram is at maximum stroke and cannot continue to go any further forward. So then the pump is working harder and harder to a point where it stalls the engine. Effectively, its pushing oil where it cannot go.

If this continues to happen, eventually the drive coupling between the engine and pump snaps. I then have to go out and remove the engine to get at it to repair. No easy or quick job.

Why oh why isnt there some way of fitting something to stop this, like in a digger, if you pull the boom all the way in and hold the lever, yes the revs drop a bit, but it clearly has a relief valve to divert the pressure.

There is one fitted on all the machines on the manifold under the ceetop, but its adjustable and is linked to the pressure of the jaw crushing .

I need an expert who can look at the whole system ti see if they can retro fit something!

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You’ve plenty of options here, but something as simple as an in-line pressure relief valve put into the ram pipe that’s feeding it, with a suitable return pipe, will allow it to blow off at whatever setting you choose, and the excess oil return to the tank.

 

You could get as fancy as a sequential valve that would actually reverse the ram a few moments after full pressure has been held constantly on.

 

 

Eddie.

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1 hour ago, LGP Eddie said:

You’ve plenty of options here, but something as simple as an in-line pressure relief valve put into the ram pipe that’s feeding it, with a suitable return pipe, will allow it to blow off at whatever setting you choose, and the excess oil return to the tank.

 

You could get as fancy as a sequential valve that would actually reverse the ram a few moments after full pressure has been held constantly on.

 

 

Eddie.

First option is better. Although I have realised that it sometimes happens on the return stroke. Would a relief valve on the pipe from the pump to the manifold not be best?

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7 hours ago, dig-dug-dan said:

First option is better. Although I have realised that it sometimes happens on the return stroke. Would a relief valve on the pipe from the pump to the manifold not be best?

I'm very surprised that there are no relief valves in the system. Sounds like a crap design.

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1 hour ago, doobin said:

I'm very surprised that there are no relief valves in the system. Sounds like a crap design.

Yes. Especially when it not only costs time to repair, and money, but a pain in the arse when it happens in an awkward place, usually on a muddy building site

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