Development: The early 1980s can be used to achieve computer-controlled electro-hydraulic system of new components, the current application of less methods: incremental digital valve Category: digital flow valve, digital pressure valve, digital directional flow valve Example: Incremental digital flow valve components: stepper motor, ball screw, valve, valve sleeve, stem, sensor, etc. Working principle: After the computer sends a signal, the stepper motor rotation, through the rolling screw into axial displacement, Driven the valve spool movement, first open the non-full-week throttling, the flow rate is small, and then open the full-week throttle, flow, up to 3600l / min. Features: 1. The valve core, valve sleeve, valve stem relative thermal expansion obtained temperature compensation, to maintain constant flow. 2. The valve has no feedback function, but with zero displacement sensor, the end of each control, the valve core can be under its control back to zero, higher repeat accuracy.