JUNE-JULY 2018 Nov-Dec 2017 - Copy - Page 78

BOOK IN SERIES This article has been excerpted from the Textbook “Electro-Hydraulic Components and Systems [1]” Applied Technology Center MSOE’s Applied Technology Center™ includes several centers of excellence, offering state-of-the-art resources and facilities. Hydraulics Versus Electrical Systems - CHAPTER 1 Fig. 1.7 shows the behavioral similarity of an electric resistor and the resistivity of a hydraulic line. The figure shows the linear proportionality between the electrical current I and the voltage difference ∆ V across an electrical resistor. For the same voltage, small resistance passes electrical current larger than largr resistance. Similarly, the figure shows the linear proportionality between the fluid flow Q and the differential pressure ∆ p across a hydraulic line. A hydraulic line with large diameter is less resistive than a hydraulic line with small diameter. So, for same differential pressure, large diameter line passes flow rate larger than small diameter line. Fig. 1.7 - Similarity Characteristics of Electrical Resistance and Hydraulic Lines 78 Equations 1.3 and 1.4 confirm the linear proportionality between the effort variable and the flow Variable in both elements. ∆ =   ∆ =   Where:  R is the resistance that depends on the dimensional parameter of the resistive element.  Electrical resistance has the units of Ohm (Ω).  Hydraulic line resistance has the units of [bar / (lit/min)]. .  .  www.ghmediabusiness.com