Description

They are composed by a relief valve (opening “B-A”)  with hydraulic dampening, and by a reverse flow annular  check valve “A-B”. Initially the flow goes to a first line  connected in parallel to the B side, not shown here, and  pressure increases until reaching the selected relief set- ting; then the relief valve opens and the second circuit is  supplied out of A port, while the actuator connected to  the B side remains pressurized. The incorporated check  valve allows the reverse motion of the actuators which  happens without specific control of the sequence, only  depending from the load/pressure conditions. Note that pressure at A needed to operate the second  actuator is additive to the relief setting, and, for this rea- son, this valve is successfully employed to energize a  secondary actuator which only requires low pressure.