The main hydraulic system of the excavator

The main hydraulic system is driven by the main pump assembly. The main pump assembly has two inclined shaft variable displacement piston pumps (upper and lower).

Its performance and method of use are exactly the same. The lower pump is directly connected to the engine through a flexible coupling. The pilot gear pump is in the main pump housing to provide pressure oil for the remote pilot operating system. The load of these three pumps constitutes the entire engine. load.

At empty load, the flow rate of each main pump is 214L/mino when the excavator is not working. The oil discharged from the two main pumps is returned to the hydraulic tank through the multi-way valve. At the same time, the main operating valve (multi-way valve) feeds back the signal of the small load to the cylinder of the excavator spare parts main pump.

Inclination control mechanism - electromagnetic proportional pressure reducing valve, reducing the displacement of the main pump, thereby reducing the output power of the engine.

When performing separate or combined actions, the maximum working pressure of the main hydraulic system is limited by the main relief valve, each stage is changed

The set pressure of the main relief valve of the triple and quadruple multi-way valve is 35. 2MPa, the set pressure of the arm control circuit is set by the secondary relief valve (overload valve). 30. OMPa, the set pressure of the boom control loop is

The viscous valve of the control circuit is set to a pressure of 33.6 MPa, and the set pressure of the relief valve of the travel control circuit is 36. 7 MPa (at this time, the flow rate is 40 L/min).

1. Load selection control

The S280F2 excavator main pump uses a load type control system, which is designed to improve work efficiency during operation.

Reduce fuel consumption. The main pump load type control system is as follows. Select different load types (L, S, H), main

The pump's output power characteristics (P-Q characteristics) are different, as shown in the figure below.

2. Rotary short circuit

When the switch at the rear of the right operation panel is closed, the electromagnetic reversing valve in the main hydraulic spare parts is reversed, and the swing mechanism is released.

Move. The electromagnetic reversing valve installed on the left and right pipelines of the swing motor is reversed to connect the pipelines on the left and right sides to make the swing loop

It becomes the open state. When the rotation is stopped, the swing device maintains the state of mechanical brake (hydraulic oil overflow). https://jnjmzm.wixsite.com/sdjygcjx