Unloading valve for a hydraulic pressure circuit

Claim 1

A HYDRAULIC CIRCUIT COMPRISING A PRESSURE SOURCE, A HIGH PRESSURE PIPE, A LOW PRESSURE PIPE, A PIPE BY-PASSING SAID PRESSURE SOURCE AND A PRESSURE REGULATOR INCLUDING A STOP VALVE MOUNTED IN SAID BY-PASSING PIPE MOUNTED TO OPEN AGAINST THE FLOW IN SAID BY-PASS PIPE, A PRESSURE CONTROLLED ACTUATING MEMBER, AND AN INLET AND AN INLET PIPE CONNECTED TO SAID HIGH PRESSURE PIPE AND TO SAID ACTUATING MEMBER TO ADMIT PRESSURE FLUID TO SAID ACTUATING MEMBER, A VALVED DISTRIBUTOR SYSTEM INCLUDING A DIFFERENTIAL PRESSURE CONTROLLED FIRST VALVE MEANS MOUNTED IN SAID INLET PIPE, SAID VALVE ADAPTED IN A FIRST POSITION BIASED BY THE PRESSURE IN SAID HIGH PRESSURE PIPE TO CONNECT SAID HIGH PRESSURE PIPE AND SAID INLET AND IN A SECOND POSITION BIASED BY THE PRESSURE IN SAID HIGH PRESSURE PIPE TO CONNECT SAID INLET AND SAID LOW PRESSURE PIPE, A SECOND VALVE HYDRAULICALLY CONTROLLED BY THE PRESSURE PREVAILING IN SAID HIGH PRESSURE PIPE AND SAID SECOND VALVE BEING HYDRAULICALLY OPERATIVELY CONNECTED WITH THE SAID FIRST VALVE DISTRIBUTOR TO CONTROL THE VALVE ELEMENT OF SAID FIRST VALVE.