Fluid joining device for power construction vehicles

A fluid joining device for power construction vehicles, comprising a first main pump connected to one or more first directional control valves in parallel and supplying pressurized fluid to one or more first actuators through the first directional control valves, a second main pump connected to one or more second directional control valves in parallel and supplying pressurized fluid to one or more second actuators through the second directional control valves, a first confluent line extending from a first center bypass line of the first pump, a second confluent line extending from a parallel line of the second pump, a logic valve connecting the first and second confluent lines together and normally closing the confluent lines but selectively opening the confluent lines in response to a pilot pressure, a first pilot line extending from the second confluent line at a position before the logic valve and selectively applying the pilot pressure to the logic valve, and a first pilot line control valve mounted to the first pilot line and normally opening the first pilot line but selectively closing the pilot line in response to a pilot pressure thereby selectively intercepting the pilot pressure supplied to the logic valve, further comprising:

• a bypass line control valve mounted to a second center bypass line of said second pump at a position where the second bypass line completely passes through the second directional control valves, said bypass line control valve normally opening the second center bypass line but selectively closing the second center bypass line in response to a pilot pressure;
• and
• a second pilot line control valve mounted to a second pilot line and controlling said second pilot line in response to an outside signal, said second pilot line extending from the first pilot line control valve and selectively driving the first pilot line control valve.