Emergency steering system of construction equipment

An emergency steering apparatus for construction machinery, comprising:

• a steering actuator;
• a bi-directional hydraulic pump capable of discharging working oil;
• a pair of driving flow paths through which the working oil from the bi-directional hydraulic pump is supplied to the steering actuator;
• an emergency hydraulic pump;
• an emergency steering valve which is supplied with the working oil from the emergency hydraulic pump through a first supplying flow path;
• a second and a third supplying flow paths configured to connect an outlet of the emergency steering valve and the pair of driving flow paths, respectively;
• a flushing valve configured to drain the working oil of any one of the pair of driving flow paths while being switched by a pressure difference between the pair of driving flow paths;
• and
• an emergency steering unit configured to switch position of the emergency steering valve to selectively connect the first supplying flow path to either the second or the third supplying flow paths;
• a pair of check valves installed at the pair of driving flow paths to be disposed between the flushing valve and the bi-directional hydraulic pump, and opened when the working oil is supplied to the pair of driving flow paths from the bi-directional hydraulic pump,
• wherein the flushing valve is opened when pressure of any one of the pair of driving flow paths is higher than that of the other as the working oil is supplied by any one of the second and third supplying flow paths, to drain the working oil which is discharged to the other of the pair of driving flow paths.