Hydraulic apparatus with pressure compensating valves

A hydraulic circuit comprising:

• a first and a second actuating valves interposed between a hydraulic pump, and a first and a second hydraulic actuators respectively;
• a first and a second pressure compensating valves interposed between said first actuating valve and said first hydraulic actuator and between said second actuating valve and said second hydraulic actuator, said first and second pressure compensating valves being arranged such that output pressures from said first and second actuating valves act on flow rate increasing side pressure receiving surfaces of respective spools thereof respectively;
• a first and a second mid-pressure hydraulic passages for connecting inlet port side hydraulic passages and outlet port side hydraulic passages in said first and second pressure compensating valves with each other, each of said first and second mid-pressure hydraulic passages being provided with a one-way valve for permitting only hydraulic oil from said outlet port side hydraulic passages to flow therethrough, and a throttle located at the inlet side of said one-way valve;
• a first and a second circulating hydraulic passages for connecting inlet side hydraulic passages of said one-way valves in said first and second mid-pressure hydraulic passages to inlet sides of load pressure ports in said first and second actuating valves;
• a first and a second comparing hydraulic passage for connecting outlet sides of the load pressure ports of said first and second actuating valves to one of and the other one of inlet ports of a main shuttle valve;
• and
• a first and a second sub shuttle valves arranged such that output pressure from said main shuttle valve is applied to one of inlet ports thereof and output pressures from the outlet sides of said one-way valves in said first and second mid-pressure hydraulic passages are applied to the other one of the inlet ports thereof, said first and second sub shuttle valves being also arranged such that output pressures thereof act on flow rate decreasing side pressure receiving surfaces of the respective spools in said first and second pressure compensating valves.