2. Option Line Control

Overall View

Enlarged View

Swing Circuit

Swing relief cut-off control circuit

This control aims for an energy-saving effect by controlling the pump in such a way as to minimize the excess oil drained from the swing motor relief valve for the starting pressure boost for a independent sharp swing operation.

When a swing operation starts, due to the swing pilot pressure sensor and P1 pressure sensor input electrical signals, computer A outputs a signal to the hydraulic pump P1 flow control proportional valve.

The discharge oil from the hydraulic pump A3 is fed to the P1 flow control proportional valve.

The output signal from computer A to the P1 flow control proportional valve controls the pilot pressure to reduce the hydraulic pump A1 side discharge flow. Also, the input signal from hydraulic pump P1 pressure sensor controls the pilot pressure to gradually increase the discharge flow. [1] Swing relief cut-off control is executed when all the conditions below are satisfied. •Travel non-operation •Sharp independent swing operation or swing + boom-down operation [2] Swing relief cut-off control ends when a condition below is satisfied. •When swing operation is stopped •Travel, boom-up, arm-out/in, or bucket-open/close operation

Pressure line Tank line Pilot pressure line Pilot tank line Electric line

1 Swing motor 13 Swing brake 2 Swing 14 5 stack solenoid valve 3 Cushion valve 15 Console lever lock switch 4 Right swing 16 N1 negative control pressure sensor 5 Left swing 17 P1 pressure sensor 6 Swing pilot pressure sensor 18 P1 flow control proportional valve 7 Remote control valve (arm, swing) 19 Hydraulic pump 8 Control valve 20 Horsepower control proportional valve 9 Travel pilot pressure sensor 21 P2 pressure sensor 10 Upper pilot pressure sensor 22 Check valve 11 Computer A 23 Oil cooler 12 Lever lock