The Kato excavator slewing motor is driven by the spool 2 of the control valve (valve block A). The pressure of the oil circuit is adjusted by the overflow valve in the rotary motor. When the rotary motor is in neutral, the rotary motor stops: when the rotary joystick moves left and right, the rotary motor moves forward or backward, causing the upper turntable to turn left and right respectively.
The overflow valve acts as a shock absorber, the supplementary valve prevents cavitation, and the balance (one-way) valve prevents the upper turntable from turning when stopped. All the above valves are installed in the machine housing on the motor.
(1) Swing priority oil circuit
As shown in Figure 3-6, when the slewing and arm excavation operations work at the same time, the oil circuit preferentially supplies oil to the slewing motor.
The pressure oil of the pump A2 flows into the arm Ⅱ through the central bypass pipe of the control valve (valve block B). The pressure oil of pump Al flows through the rotary spool and small arm spool of the control valve (valve block A), but the pilot pressure acting on the small arm I spool limits its stroke and shortens the stroke of the entire small arm I spool . By shortening the oil circuit, sufficient pressure can be maintained to drive the rotary motor.
(2) Swing parking brake
When the joystick is in neutral, the brake is turned to stop working, and the walking joystick is operated to make the pilot pressure pass the solenoid valve block to release the brake.
