Generally speaking, if the hydraulic system needs a flow change, especially if the time for large flow is shorter than that for small flow, Hongyi hydraulic manufacturer suggests that everyone should preferably use double pump or variable pump.

For example, the feed mechanism of the machine tool needs large flow when fast forwarding. When working, the flow rate is small, and the difference between the two is dozens of times or even more. In order to meet the large flow required by the hydraulic cylinder during fast forwarding, the pump with large flow should be selected.

However, when working, the flow required by the hydraulic cylinder is very small, making most of the high-pressure hydraulic oil overflow through the overflow valve, which not only consumes power, but also makes the system hot.

In order to solve this problem, variable vane pump can be selected. When fast forwarding, the pressure is low and the pump displacement is maximum. When working, the system pressure rises, the pump automatically reduces the displacement, and basically no oil overflows from the overflow valve.

Double vane pump can also be used, the large and small pumps supply oil to the system at low pressure, the small pump supplies oil at high pressure and low flow when working at high pressure, and the large pump supplies oil at low pressure and high flow after unloading by unloading valve.

For details, please consult: https://www.vanepumpfactory.com/