Variable system of hydraulic pump

In the variable system of hydraulic excavator, stepless speed regulation is realized by volume variable. There are three main adjustment methods: variable pump - quantitative motor speed control, quantitative pump variable motor speed control, variable pump variable motor speed control.

The combination of variable displacement pump and quantitative motor is adopted in hydraulic excavator to realize stepless variable, and both are double pump and double loop form.

According to whether the variables of the two circuits are related, they are the two forms of the power variable system and the full power variable system. The power of each pump variable system with a mechanical power adjustment, change of flow pump is only influenced by the change of their own pressure, the pressure change has nothing to do with the other circuit, namely the pump two loop independently constant power variable, two pump has a bucket engine output power.

The two oil pumps in the full power variable system are regulated by a total power adjustment mechanism, so that the swing angles of the two oil pumps are always the same, and the synchronous variables and the flow rate are equal. The total pressure of the system is determined by the change of the flow rate, and the power of the two pumps is different in the range of variables. The regulating mechanism has two forms of mechanical linkage and hydraulic linkage.