When the main pump located in the upper body sends oil to the travel motor located in the lower body, the upper and lower bodies will rotate relatively. In order to prevent twisting of the hydraulic hose, a center rotary joint is installed in the center of the car body.
working principle:
As shown in the figure, the center rotary joint is composed of a shell and a mandrel. The shell is installed on the lower body, and the mandrel is installed on the upper body.
Open an annular groove equal to the number of pipes on the mandrel. The hydraulic oil from the mandrel inlet is supplied to the travel motor from the vertical holes on the housing through these oil grooves.
Even if the mandrel continuously rotates with the upper car body, the groove on the housing keeps clear with the oil port on the mandrel, so that hydraulic oil can enter and exit freely.
