Brake valve
Swing parking brake
Rotary parking brake is shown in Figure 5-9. The Kobelco excavator slewing parking brake is a wet multi-disc brake. The brake is released only when the brake release pressure oil S enters the brake cylinder 6 (normally closed brake). When performing the swing operation and the leather) arm retraction operation (that is, when the solenoid valve 9 has not been energized), the brake release pressure oil S comes from the pilot pump 10 when performing other operations than the swing and arm retracting operation, or when the engine When stopping, the brake release pressure oil S is connected with the hydraulic oil tank, and the parking brake is automatically realized by the spring 1.
When the brake is in the ON position (i.e. other than the swing and/or stick retract operation), the signals from the pressure switch 7 and/or stick retract pressure switch 8 are not transmitted to the pump valve controller (PVC), which keeps the solenoid valve 9 energized (ON). When the solenoid valve 9 is energized, the brake release pressure s is released to the tank port, so that the force of the spring 1 passes through the piston 2 downward, so that the steel plate 3 is engaged with the circumferential portion of the cylinder 6, the friction plate 4 and the motor housing The inner surface is engaged. The friction force is equal to the thrust load, and the steel sheet 3 and the cylinder 6 are braked by the friction force.
When the brake is in the OFF position (that is, when the interrogation operation and/or the stick retracting operation are performed), the signal from the co-rotating pressure switch 7 and/or the stick retracting pressure switch 8 is transmitted to the pump valve controller (PVC ), the solenoid valve 9 is powered off. Then, the brake release pressure SI is pushed upward, against the spring 1, and the piston is separated from the steel plate 3 and the friction plate 4, thereby releasing the brake.
