The rotary parking brake is a wet multi disc brake, which is composed of spring, brake piston, steel plate, friction plate, etc. it ensures that when the excavator stops on the slope, the upper turntable will not slide due to its own gravity. At the same time, when the main controller fails or starts to stop, the brake will lock the upper turntable. The rotary parking brake is the key part of the upper turntable of excavator for locking and releasing.
1. The slewing brake is released (released)
The rotary parking brake relies on the pilot pressure oil from the pressure reducing valve and the internal spring of the brake piston to control the rotary brake valve and realize the movement of the brake piston. When the rotary locking switch is off and the operating lever is moved, the PPC oil pressure switch transmits the electric signal to the main controller, and then the main controller outputs the electric signal to power on the rotary brake solenoid valve. After the rotary brake solenoid valve is powered on, the pilot pressure oil from the pressure reducing valve enters the brake of the rotary motor through the rotary brake solenoid valve, If the brake piston is opened by overcoming the spring force, the slewing brake is opened and the brake is released.
2. Slewing brake locking brake (brake application)
When the operating handle stops at the neutral position for 4S, the PPC oil pressure switch signal is transmitted to the main controller, and the main controller cuts off the output drive signal, so that the rotary brake solenoid valve is powered off. The pilot oil from the self reducing valve can not reach the brake piston, and the brake piston realizes the parking brake under the action of spring force.
