When the excavator works, its chassis and the upper operating body need to do relative rotation movement, then how to achieve this movement that requires 360° rotation, requires the core component of the central rotation joint. When the excavator is rotating, the hydraulic oil is delivered to the walking motor through the rotary joint, and the hydraulic oil is connected to the internal cylinder from the main control valve, and the oil circuit of the walking motor is connected to the shell structure. The inner cylinder body is cast from top to bottom with a circular groove (that is, the oil passage), and the outer shell is also cast with a small groove corresponding to the groove (used to install the rotary joint seal ring). When the machine is rotating, the shell is fixed, and there is relative movement between the internal cylinder and the shell (the cylinder rotates in the shell). Because the oil passage is circular, the machine can turn arbitrarily within the circumference, and can keep the shell oil passage through the corresponding mandrel oil passage to achieve continuous rotation.
The central rotary joint of the excavator is composed of two parts: the internal cylinder body and the external shell, the shell is provided with a flange, which is fixed to the center of the rotary support, the shell is connected to the on-board pipeline, and the mandrel is connected to the off-board pipeline.
