For a relatively long period of time, Axiang has brought you content with a certain degree of professionalism, which requires a certain foundation of engineering machinery knowledge to understand. However, those who like iron armor are not necessarily those working in the construction machinery industry. There are also many excavator enthusiasts, and many of our industry personnel have gradually changed from enthusiasts to "old excavators". driver".
In the comments on Axiang’s articles in previous issues of the Tiejia Engineering Machinery Network’s WeChat backend, we also saw some readers leaving messages hoping that Axiang could share some entry-level interesting knowledge. This is a must, after all, we We want more enthusiasts to become “experienced drivers”!
So in this issue, Axiang will talk about some interesting popular science knowledge. Why can the excavator rotate 360 ??degrees infinitely? Will the oil pipe connected to the lower body not be twisted and broken? Axiang has been fascinated by excavators since he was in elementary school. This problem has been bothering me from elementary school to high school. It was only after I came into contact with the Internet that I understood the reason. It turns out that all this is due to a small component on the excavator - the central rotary joint. So let’s talk about this little knowledge in this issue!
Hydraulic circuit of the lower car body
The structure and principle of the central rotary joint (oil distribution cup)
The working principle of the central rotary joint
< p>◆Hydraulic circuit of the lower bodyOur common excavators are all fully hydraulic, that is, the movement of all components on the excavator is driven by hydraulic pressure. The main action of the lower body is to move forward and backward. Some small excavators are equipped with a dozer blade, so they also have the lifting function of the dozer blade.
So the hydraulic circuit of the lower body of the excavator generally includes the left and right traveling motor hydraulic circuits and the working hydraulic circuit of the bulldozer blade.
Travel motor hydraulic circuit:
When the travel joystick is pushed, the travel pilot hydraulic oil pushes the distribution valve stem to move, connecting the circuit from the hydraulic pump to the hydraulic motor, and the high-pressure oil It reaches the traveling motor through the central rotary joint, and then returns to the hydraulic oil tank through the central rotary joint.
Four oil pipes for the traveling motor
When switching to "rabbit gear", another line of hydraulic oil reaches the hydraulic motor through the central rotary joint, pushing the high-low speed switching piston inside the traveling motor, and the oil returns through The central swivel joint returns to the hydraulic tank.
Dozer blade hydraulic circuit:
When executing the dozer blade lifting action, the hydraulic oil reaches the rod cavity of the dozer blade cylinder through the central rotary joint through the distribution valve, and the rodless cavity hydraulic pressure The oil returns to the tank via the central swivel joint.
When executing the dozer blade lowering action, the hydraulic oil reaches the rodless cavity of the dozer blade cylinder from the distribution valve through the central rotary joint, and the hydraulic oil in the rod cavity returns to the tank through the central rotary joint.