浮子由一根强度和柔性很高的钢丝挂于测量鼓上。在液面没有变化时，浮子平衡在液面上，浮子所受到的向上的拉力，即钢丝上的张力等于浮子的重力减去它所受的浮力，钢丝上的张力通过杠杆滑轮直接传到高准确度的力传感器上，该力被设定到伺服机构的控制器中，当液位下降时浮子失去向上浮力，则测力传感器所测到的张力增加。该力与伺服传感器预先设定值进行比较，使伺服马达带动测量股放下钢丝，浮子去跟踪液位，直到浮子所受的拉力等于传感器设定值。当液位上升时，过程正好相反。
The float is hung on the measuring drum by a steel wire with high strength and flexibility. When the liquid level remains unchanged, the float is balanced on the liquid surface. The upward pulling force on the float is equal to the gravity of the float minus its buoyancy. The tension on on the steel wire is transmitted directly to the force sensor with high accuracy through the lever pulley. The force is set to the controller of the servo mechanism when the liquid level is set. When the float loses its upward buoyancy, the tension measured by the force sensor increases. The force is compared with the preset value of the servo sensor, so that the servo motor drives the measuring strand to lower the steel wire, and the float tracks the liquid level until the tension of the float equals the preset value of the sensor. When the liquid level rises, the process is just the opposite.