What does the switch under the front of weighing scale do? There are three gears.

The changeover switch has three gears, the left 45 is 1 standby, the middle is manual, and the right 45 is 2 standby 1. When the changeover switch is in any gear, four pairs of points are on, two pairs are 1# pumps, and the other two pairs are 2# pumps. The model of this transfer switch is LW5-D0724.