Before demolition of hydraulic cylinders,should make hydraulic loop.then discharging pressure.Otherwise,when fuel tank to link the pipeline joints and loosening,loops of hign oil will be quickly ejected. when hydraulic circuit relief pressure,it should loose handwheel at overflow valve and other places or regulator screw,to make pressure oil load-off, and then cut off the power or disconnect the power source, to make hydraulic device stop operation.That's right?