Patent ID: 8572957

Claim:
A hydraulic system for construction equipment, comprising: first, second, and third variable displacement hydraulic pumps connected to an engine; a first traveling control valve installed in a center bypass path of the first hydraulic pump to control the start, stop, and direction change of a left traveling motor; first control valves installed in the center bypass path on a downstream side of the first traveling control valve and connected together through a parallel line to control hydraulic fluid being supplied to a boom cylinder, a swing motor, and an arm cylinder; a second traveling control valve installed in a center bypass path of the second hydraulic pump to control the start, stop, and direction change of a right traveling motor; second control valves installed in the center bypass path on a downstream side of the second traveling control valve and connected together through a parallel line to control hydraulic fluid being supplied to the boom cylinder, a bucket cylinder, and the arm cylinder; a first path connected to a discharge flow path of the third hydraulic pump and connected to the center bypass paths of the first and second hydraulic pumps on the downstream sides of the first and second traveling control valves through first and second check valves, respectively; and a second path connected to the discharge flow path of the third hydraulic pump and connected to the parallel lines of the first and second hydraulic pumps through third and fourth check valves, respectively.