JUNE-JULY 2018 Nov-Dec 2017 - Copy - Page 83

BOOK IN SERIES 1.1.2.4- Directional Controllers As shown in Fig. 1.12, switches and buttons are used in electrical systems. Directional control valves are used in hydraulic systems. Fig. 1.12 - Directional Controllers As shown in Fig. 1.13, the term Normally-Closed means an electrical switch closes the circuit and electrical current passes to drive the electrical motor. On the other hand the same term means a hydraulic valve terminates the flow to stop the hydraulic motor. 83 www.ghmediabusiness.com Fig. 1.13 - Electrical Switch versus Directional Valve