Pressure Drop in Chuck

Dear Experts

We have a turning machine with chuck having hi/lo pressure. Required pressure for Hi chucking pressure is 15 bars and for low it is 8 bars
Problem that we are facing is during changeover from hi to lo chuck pressure, hi pressure is increasing upto 18 bars and lo upto 11/12 bars
Please refer to spec of valve attached
We have taken following actions :

1. Taken out and serviced hi ands low pressure direction control valve - manually pushed the valve to feel movement of spool inside, found alright
2. This valve operating with 110VDC, replaced valve with valve operating with 24V DC - after electric modification via relay
3. Check valve opened up and serviced
4. No leakages observed in the hydraulic power pack

Request your suggestions

Regards

Without knowing more about the system, it is difficult to say what the problem is.

Where is the pressure being measured? At the chuck cylinder ''A'' or ''B'' line, or on the ''P'' line to the valve?

The valve in the picture is a closed center valve, so ''P'' would show pump relief valve pressure when switching.

Once the valve has shifted, does the pressure remain at 18 or 11 bar?

Is the pressure gauge reading correctly? Measuring against another known good gauge is sometimes required.

Apologies for late response

Both hi and lo Pressure connected to P line of Pressure reducing valve

After changeover from hi to lo, hi pressure increases upto 18 bars (from 15 bars) and lo pressure increases upto 11 bars (from 8 bars) , both remain at 18 and 11 respectively for entire machining of component

We have swapped pressure gauges with other OK sets, still it is same & moreover once we found job got slightly declamped from jaws of chuck although did not come out of it completely

We are organizing new set of Check valve and Pressure reducing valve for replacement as servicing of these two valves did not yield any difference

Regards

What is the pressure at the chuck actuating cylinder? Is the cylinder leaking internally?

Quote:

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Originally Posted by M.RISHIKESH

Dear Experts

We have a turning machine with chuck having hi/lo pressure. Required pressure for Hi chucking pressure is 15 bars and for low it is 8 bars
Problem that we are facing is during changeover from hi to lo chuck pressure, hi pressure is increasing upto 18 bars and lo upto 11/12 bars
Please refer to spec of valve attached
We have taken following actions :

1. Taken out and serviced hi ands low pressure direction control valve - manually pushed the valve to feel movement of spool inside, found alright
2. This valve operating with 110VDC, replaced valve with valve operating with 24V DC - after electric modification via relay
3. Check valve opened up and serviced
4. No leakages observed in the hydraulic power pack

Request your suggestions

Regards

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Very straight forward the Pressure Relief valve is not working correctly, or some one has adjusted the Pressure Relief valve, for it to have a higher pressure

Thanks for your response, we found some issue in precondition ie Casting also, ok under observation