Hydraulic Actuators: Cylinders – Types and construction, Application, Hydraulic cushioning – Hydraulic motors - Control Components : Direction Control, Flow control and pressure control valves – Types, Construction and Operation – Servo and Proportional valves – Applications – Accessories : Reservoirs, Pressure Switches – Applications – Fluid Power ANSI Symbols – Problems

1. UNIT-II
HYDRAULIC ACTUATORS AND
CONTROL COMPONENTS
1

2. Hydraulic system consists of following components
Power sources units:
1) Tank or reservoir
2) Filters
3) Hydraulic Piping
Pressurized tanks, Vented tanks, Oil cooler
Suction filter, return line, Pressure line filters
Hose , Pipe, Fittings, Pressure gauge,
Temperature gauge
4) Positive displacement Pumps Internal/external gear Pump
Screw,lobe,Vane ,Plunger pump, Piston
pump
Power Control Units:
1) Flow control valves
2) Check valves
3) Pressure control valves
Regulating type, Control type
NRV,Pilot operated check valves
Pressure Relief valves , Unloading valves,
Sequence valves, Pressure-reducing valves ,
Counterbalance valves, Safety Valve
Poppet, Spool , Rotary valves, One,two,three
4)Direction control valves
way,
DRIVE units:
1) Actuators Linear, Rotary, 1,2CYLINDERS,
Telescopic cylinder, Hydraulic motors
2

3. Hydraulic
Systems
3

4. Basic Components in Hydraulic Systems
4

5. 5

6. 6

7. 1.RESERVOIR
7

8. 8

9. 9

10. 10

11. HowReservoirs Work
11

12. 12

13. 2. Filters
13

14. 14

15. 15

16. 16

17. 17

18. 18

19. Hydraulic oil contamination
19

20. Particles In Hydraulic Oil
20

21. Contaminant TypesAndCauses
21

22. Abrasion Classes
22

23. 23

24. 24

25. 25

26. 26

27. 27

28. 28

29. A hydraulic hose is a high-pressure, synthetic
rubber, thermoplastic or Teflon reinforced hose
that carries fluid to transmit force within hydraulic
machinery
3.Hydraulic hose
29

30. 30

31. 31

32. 32

33. 33

34. 34

35. 35

36. 4. Hydraulic steel
PIPES
36
It also carries fluid to transmit
force within hydraulic machinery

37. 37

38. 38

39. • Positive displacement
pump (Gear Pump): a
specific amount of fluid
passes through thepump
for eachrotation
• Centrifugal pump (Vane
Pump): no specific
amount of fluid flow per
rotation; flow dependson
speed of blades
39

40. Positive displacement vs Centrifugal pump
Curve
40

41. PISTONPUMPS
PLUNGERPUMPS
DIAPHRAGMPUMPS
RECIPROCA
TINGPUMPS
GEARPUMPS
LOBEPUMPS
SCREWPUMPS
CAMPUMPS
V
ANEPUMPS
ROT
AR
YPUMPS
POSITIVEDISPLACEMENTPUMPS CENTRIFUGALPUMPS
PUMPS
41

42. 42

43. • Displacement relates to how the output of the pump reacts to
system loads
– Non-positive-displacement pumps produce flowvariations
due to internalslippage.
– Positive-displacement pumps produce
a constant output percycle
43

44. • A non-positive-displacement pump haslarge
internalclearances
– Allows fluid slippage in thepump
– Results in varying flow output as system load varies
44

45. Key Feature of a V-Displacement
Pump
• FixedDisplacement Pump
– A fixed volume of fluids
will be provided in each
revolution
Variable Displacement
Pump
_The volume of supplying
fluids may be change
based on demands
45

46. 46

47. 47

48. 48

49. Vane Pumps
49

50. 50

51. 51

52. 52

53. 53

54. 54

55. 55

56. 56

57. Internal
Gear
Pump
57

58. Internal Gear Pump
58

59. Internal Gear Pump
59

60. • Operation of a lobepump
60

61. • A typicalscrewpump
61

62. Operation Principle of Piston Pumps
62

63. 63

64. 64

65. A rotor-gear pump is a variation of the internal-gear pump.
65

66. 66

67. Rotor-gear Pumps
67

68. 68

69. 69

70. Hydraulic oil cooler
70

71. Valves
71
If the pump is the heart of a hydraulic system then
the valve is the brain.
Valves are used to perform a large variety of
governing and controlling functions.
Types:
• pressure control valves
• flow control valves (Volume control valves)
• check valves (non-return valves)
• directional control valves

72. 72

73. Form:
a) Spherical
b) c) d) e) Conical
f) Plate
g) Spool valve
Poppet
valve
Aspects of classification
73

74. Flowvalves
74
Basics:
The velocity of hydraulic cylinders can be influenced by the flow rate.
This can be done by an adjustable pump or by a flow rate control valve.
The flow rate is changed by changing an orifice surface area or by changing the
pressure difference on a resistance or dividing the flow rate.
Advantages of flow valves
are:
 simplicity
 safe operation
 good dynamic behaviour
 precision
Disadvantage:
 the relatively high energy losses
Types:
 Restrictor valves (throttle valves)
 Flow control valves
 Flow dividing valves

75. 75

76. Flow Control
Valves
76

77. 77

78. 78

79. Control Valves Regulating Valves
Restrictor Orifice One Way Two Way
79

80. 80

81. 81

82. 82

83. 83

84. (a) In flow control
84
(b) out flow control

85. 85

86. 86

87. 87

88. 88

89. Pilot pressure to open check valve
89

90. SHUTTLE VALVE
90

91. 1. Relief valves
2. Unloading valves
3. Sequence valves
4. Pressure-reducing valves
5. Counterbalance valves
6. Safety Valve
91

92. 92

93. 93

94. 94

95. Pressure relief
95
valve

96. 1- Direct Acting Relief Valve
(PRV)
96

97. 97

98. Fs > Fp
98
Fs < Fp

99. Pressure relief
valve
99

100. 100

101. 101

102. 102

103. Normal flow, no over load
103
Pressure relief valve

104. 2- Pilot-Operated Relief Valve
104

105. 105

106. 2- Pilot-Operated Relief Valve
106

107. 2- Pilot-Operated Relief Valve
107

108. Unloading valves
108

109. Unloading valves
109

110. Sequence valves
110

111. Sequence valves
111

112. 112

113. Pressure
reducing
valves
113

114. Pressure-reducing valves
114

115. Counterbalance valves
115

116. Counterbalance valves
116

117. 117

118. 118

119. 119

120. 120

121. Directional Control Devices
• Typical spool valve
121

122. 122

123. 123

124. 124

125. 125

126. 126

127. 127

128. 128

129. 129

130. 130

131. 131

132. 132

133. 133

134. 134

135. 135

136. 136

137. Solenoid Operated SpoolValves
137

138. 138

139. 139

140. 140

141. 141

142. 142

143. PRESSURE SWITCH
A pressure switch is a form of switch that closes an electrical
contact when a certain set fluid pressure has been reached on its
input. The switch may be designed to make contact either on
pressure rise or on pressure fall. Pressure switches are widely
used in industry to automatically supervise and control systems
that use pressurized fluids.
Another type of pressure switch detects mechanical force; for
example, a pressure-sensitive mat is used to automatically open
doors on commercial buildings. Such sensors are also used
in security alarm applications such as pressure sensitive floors.

144. ACTUATORS
144
Hydraulic actuators convert the fluidpower
from the pump into mechanical work.
A hydraulic cylinder is a linearactuator.
A hydraulic motor is a rotaryactuator.

145. 145

146. 146

147. 147

148. 148

149. 149

150. 150

151. 151

152. 152

153. Telescopic Cylinder
153

154. HYDRAULIC MOTORS
154
 The function of hydraulic motors
is t
h
eopposite of hydraulic pumps:
 Pump
 It draws in oil and displaces it, converting mechanical f
o
r
c
e
into fluid force.
 Motor
 Oil under pressure is forced in and spilled out, converting
fluid force into mechanical force.

155. 155

156. GEAR MOTORS
156

157. 157

158. 158

159. 159

160. 160

161. 161

162. 162

163. 163

164. 164

165. 165

166. 166