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ECT 459. Lecture 4 Pneumatics and Hydraulics. System Control. Hydraulic and Pneumatic systems are controlled by the supply and control of fluid pressure, flow rate, and flow direction. Applications. Hydraulic and Pneumatic control systems are found in: Construction Equipment
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ECT 459 Lecture 4 Pneumatics and Hydraulics
System Control Hydraulic and Pneumatic systems are controlled by the supply and control of fluid pressure, flow rate, and flow direction.
Applications Hydraulic and Pneumatic control systems are found in: • Construction Equipment • Factory Automation • Aircraft Flight Systems • Shipboard Controls • Military Vehicles • Farm Equipment
Measured Variables • Load Position • Load Speed • Load Pressure • Load Torque • Spool Displacement • Flow Rate • Pump Output Pressure • Pump Displacement • Pump Speed
Electronic Equivalents Tank Ground Pump Battery Pressure Gage Voltmeter Flow Meter Ammeter Relief Valve Voltage Regulator Directional Valve Switch Accumulator Capacitor Filter Low-Pass Filter Restrictor Resistor Check Valve Diode Hydraulic Motor Electric Motor
Additional Valves • Pump Side Relief Valves • Load Side Relief Valves • Cross-Over • Line-Tank • Check Valves
Filters • Suction Line • Pressure Line • Return Line • Case Drain • Kidney Loop
Control • Manual vs. Electronic • Fixed vs. Variable Displacement • Open vs. Closed Center • Parallel vs. Series • Open vs. Closed Circuit
Valve Types • Ports • 2, 3, 4 • Positions • 1, 2, 3, 4 • Center • Open, Closed • Actuation Method • Electrical, Mechanical, Pilot • Metering Element • Sliding Spool, Rotating Spool, Poppet (ball) • Control Purpose • Pressure, Flow, Both (proportional)
Actuation Methods • Mechanical Direct • Electrical Direct • Mechanical Pilot • Electrical Pilot
Valve Mounting • Cartridge Valves • Manifold Blocks
Hydraulic Sizing • Pressure • Flow Rate • Stroke Rate • Area • Torque