Generally speaking, the Agricultural Machinery Hydraulic Pumps Manufacturers smaller the pressure loss produced by the hydraulic valve flow (such as rated flow), the better, the more flow under the same pressure loss, the better, the pressure flow characteristics of the hydraulic valve can be measured with the same shape and size. The smaller the pressure loss, the better the performance, and the better the flow under the same pressure difference.

1. Some hydraulic valves with oil discharge ports need to pass through the oil tank directly, do not connect with the main oil return pipe in the system, otherwise it will cause unexpected consequences. For example, when the oil discharge pipe of the pressure reducing valve is connected to the main oil return pipe, the flow rate in the main oil return pipe of the system will change at any time, resulting in the constant change of the pressure loss of the oil in the oil return pipe, thus causing the output pressure of the pressure reducing valve to be unstable.

2. For some electro-hydraulic reversing valves of China Tractor Gear Pumps, which are unloaded in the middle position, the electro-hydraulic valve cannot be reversing if the control oil port is not separately pre-connected with control oil. Therefore, the internal control electro-hydraulic reversing valve needs to add a pre-pressure valve or a back-pressure valve to the oil return port at its P port.