Hydraulics Basic Level

1 Tasks of a hydraulic installation______________________________ 7
1.1 Stationary hydraulics____________________________________8
1.2 Mobile hydraulics ______________________________________10
1.3 Comparison of hydraulics with other control media _______________ 11


2 Fundamental physical principles of hydraulics ___________________ 13
2.1 Pressure___________________________________________13
2.2 Pressure transmission__________________________________18
2.3 Power transmission___________________________________ 19
2.4 Displacement transmission ______________________________19
2.5 Pressure transfer_____________________________________23
2.6 Flow rate__________________________________________25
2.7 Continuity equation___________________________________26
2.8 Pressure measurement_________________________________30
2.9 Temperature measurement______________________________31
2.10 Measurement of flow rate______________________________31
2.11 Types of flow_______________________________________31
2.12 Friction, heat, pressure drop ____________________________35
2.13 Energy and power ___________________________________41
2.14 Cavitation________________________________________ 51
2.15 Throttle points_____________________________________ 53


3 Hydraulic fluid_______________________________________ 57
3.1 Tasks for hydraulic fluids _______________________________ 57
3.2 Types of hydraulic fluid________________________________ 58
3.3 Characteristics and requirements__________________________ 59
3.4 Viscosity__________________________________________ 60


4 Components of a hydraulic system __________________________ 67
4.1 Power supply section __________________________________ 67
4.2 Hydraulic fluida_____________________________________ 67
4.3 Valves____________________________________________ 68
4.4 Cylinders (linear actuators)______________________________ 70
4.5 Motors (rotary actuators) _______________________________ 71

5 Graphic and circuit symbols_______________________________ 73
5.1 Pumps and motors____________________________________ 73
5.2 Directional control valves _______________________________ 74
5.3 Methods of actuation __________________________________ 75
5.4 Pressure valves ______________________________________ 76
5.5 Flow control valves ___________________________________ 78
5.6 Non-return valves ____________________________________ 79
5.7 Cylinders __________________________________________ 80
5.8 Transfer of energy and conditioning of the pressure medium_________ 82
5.9 Measuring devices_____________________________________ 83
5.10 Combination of devices________________________________ 83


6 Design and representation of a hydraulic system _________________ 85
6.1 Signal control section __________________________________ 86
6.2 Hydraulic power section ________________________________ 87
6.3 Positional sketch_____________________________________ 90
6.4 Circuit diagram______________________________________ 91
6.5 Components plus technical data___________________________ 92
6.6 Function diagram____________________________________ 94
6.7 Function chart ______________________________________ 95


7 Components of the power supply section_______________________ 97
7.1 Drive_____________________________________________ 97
7.2 Pump ____________________________________________ 99
7.3 Coupling__________________________________________ 107
7.4 Reservoir _________________________________________ 107
7.5 Filters ___________________________________________ 109
7.6 Coolers___________________________________________ 120
7.7 Heaters___________________________________________ 122


8 Valves_____________________________________________ 123
8.1 Nominal sizes_______________________________________ 123
8.2 Design ___________________________________________ 125
8.3 Poppet valves_______________________________________ 126
8.4 Spool valves________________________________________ 127
8.5 Piston overlap _______________________________________ 129
8.6 Control edges_______________________________________ 134

9 Pressure valves_______________________________________ 137
9.1 Pressure relief valves __________________________________ 137
9.2 Pressure regulators___________________________________ 144


10 Directional control valves_______________________________ 149
10.1 2/2-way valve _____________________________________ 153
10.2 3/2-way valve _____________________________________ 157
10.3 4/2-way valve _____________________________________ 159
10.4 4/3-way valve _____________________________________ 162


11 Non-return valves ____________________________________ 167
11.1 Non-return valve ___________________________________ 168
11.2 Piloted non-return valve ______________________________ 172
11.3 Piloted double non-return valve__________________________ 175


12 Flow control valves___________________________________ 179
12.1 Restrictors and orifice valves____________________________ 180
12.2 One-way flow control valve____________________________ 184
12.3 Two-way flow control valve____________________________ 185


13 Hydraulic cylinders___________________________________ 193
13.1 Single-acting cylinder ________________________________ 194
13.2 Double-acting cylinder _______________________________ 199
13.4 Seals___________________________________________ 200
13.5 Types of mounting__________________________________ 202
13.6 Venting_________________________________________ 202
13.7 Characteristics_____________________________________ 203
13.8 Buckling resistance _________________________________ 205
13.9 Selecting a cylinder__________________________________ 207


14 Hydraulic motors____________________________________ 211
15 Accessories ________________________________________ 215
15.1 Flexible hoses _____________________________________ 217
15.2 Pipelines________________________________________ 223
15.3 Sub-bases _______________________________________ 226
15.4 Bleed valves______________________________________ 228
15.5 Pressure gauges ___________________________________ 229
15.6 Pressure sensors___________________________________ 230
15.7 Flow measuring instruments___________________________ 231


16 Appendix ________________________________________ 233


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