Hi. I've got a question fir the experts... I am rebuilding my JCB JS450. The 2 stage relief solenoid on the schematic connects to the main control Valve at Port Pi1 (see image). However Pi1 is an adjustment nut on a check valve. Really confused how that is possible.... Thanks in advance
I don't see any image.
Looking at the diagram you posted. The portion circled in blue, that's your low side pressure setting. The portion circled in red is the high side. It takes the addition of pilot oil and sticks it on top of your already established low side pressure setting. For example you have the low side set at 200 kg , when you hit boost or raised or whatever your mfr calls it you can add up to pilot pressure on top of that. So if your pilot is 33 kg, you could adjust up to 233 kg. This is also raised in travel on most equipment. Your 2 stage relief will have 2 mechanical adjustments. Low side or base and highside or raised. Raised only comes in play with a pilot signal from a solenoid to add pilot oil to the end of the relief stacking hydraulic pressure on top of spring pressure. Hope this clears it up.
Ok.. So I need to make a plan to connect the solenoid hose onto the adjustment nut. Just have no idea how I'm going to achieve the connection and still be able to keep the lock/adjust nut on the spring.... would have been helpfull to have a T connection there...
That thing should have a whole buncha wrench flats and jam nuts on it. Can you attach a pic?
It's the same as this port... A lock nut around a Lnkey adjustment bolt that puts pressure on the internal spring holding the check valve on its seat...
That's weird. Usually an external cartridge valve. That looks more like a port relief
Maybe i have to go back to the drawing board to get confirmation on where the Pi1 port is on the Control Valve. Maybe I'm reading the Control Valve diagram wrong. See the 2 views on the diagram....
I'm starting to think that function was added later on the model Control Valve. Maybe my model is an older model because the Port does not look the same at all..... But if not there where would it have been connected to?
I don't know the particulars of your machine. I'm attaching the description of 2 stage reliefs from Volvo and Komatsu to help you identify what you're looking for. Hope this helps. Good luck
Thankyou. I will give it a read. I wondered if there may be a member on the forum that owns a JCB JS330 or 450 that could be of any help to have a look on the back of their control Valve.... maybe