It is suggested to superimpose a bidirectional throttle valve or a unidirectional throttle valve. When the oil cylinder descends, you can descend quickly under the self-weight of the piston rod of the oil cylinder without high pressure, but the flow of the pump cannot be supplied, which makes the pressure maintaining valve (hydraulic lock) open, close, open and vibrate back and forth. Or adding a balance valve can also solve the problem you said!