The heating of hydraulic system of forging operator is very serious all the time, especially in summer, the heating of system is more serious, and the oil temperature can reach about 70 "C. As the oil temperature increases, the viscosity of the oil decreases, causing oil leakage everywhere in the system. Moreover, the internal leakage of the pump increases, the volumetric efficiency decreases, and the pump cannot work. The high oil temperature greatly reduces the service life of the seal. It not only affects the production, but also causes a lot of waste of engine oil. In the first half of 1978, we solved the long-standing problem of system heating.

The hydraulic system of the forging operator used to use the "O" three position four-way manual reversing valve. When the operator completes an action and the manual reversing valve is in the middle position, the high-pressure oil from the main pump returns to the oil tank through the relief valve (in order to meet the need of clamping force, the pressure of the relief valve is adjusted to 120 kg / mm2). In this way, the pump has been working under high pressure since it was started. Only one part of the mechanical energy converted from electrical energy has done hard work to make the operator act, while the rest has changed into heat energy, resulting in the rise of oil temperature.