Chapter 1 Hydraulic Oil and Fundamental Hydraulic Fluid Mechanics 1.1 Hydraulic Oil 1.1.1 Basic physical characteristics 1.1.2 Requirements and selection of hydraulic oil 1.2 Hydrostatics 1.2.1 Characteristics of static pressure 1.2.2 Generation and transmission of static pressure 1.3 Hydrodynamics 1.3.1 Basic concept 1.3.2 Equation of continuity—conservation of mass 1.3.3 Bernoulli equation—conservation of energy 1.3.4 Equation of momentum——conservation of momentum 1.4 Characteristics of Fluid Flow in Pipeline 1.4.1 States of fluid flow and Reynolds number 1.4.2 Hydraulic pressure drop in pipe calculation 1.5 Flow Rate Calculation through Orifice and Clearance 1.5.1 Flow rate calculation through orifice 1.5.2 Flow rate calculation through clearance 1.6 Hydraulic Shock and Cavitation Problems Chapter 2 Introduction of Hydraulic Transmission 2.1 Basic Concept of Hydraulic Transmission 2.2 Operating Principle and Characteristics of Hydraulic Transmission 2.2.1 Operating principle of hydraulic transmission 2.2.2 Operating characteristics of hydraulic transmission 2.3 Examples of Hydraulic Transmission System～ 2.3.1 Hydraulic jack 2.3.2 Hydraulic clamp 2.3.3 Grinding machine 2.4 Construction of Hydraulic Transmission System 2.5 Simplified Graphics Symbols of Hydraulic Transmission System 2.6 Advantages and Disadvantages of Hydraulic Transmission System 2.6.1 Advantages 2.6.2 Disadvantages 2.7 History and Application of Hydraulic Transmission System Problems Chapter 3 Hydraulic Pumps and Hydraulic Motors 3.1 Overview of Hydraulic Pumps and Hydraulic Motors 3.1.1 Operating principle 3.1.2 Main performance parameters 3.2 Typical Hydraulic Pumps and Hydraulic Motors 3.2.1 Gear pumps and gear motors 3.2.2 Vane pumps and vane motors 3.2.3 Piston pumps and piston motors 3.3 Selection of Hydraulic Pumps and Hydraulic Motors Problems Chapter 4 Hydraulic Cylinders 4.1 Classification and Speed—thrust Performance 4.1.1 Piston cylinders 4.1.2 Plunger cylinders 4.1.3 Swing cylinders 4.1.4 Combined cylinders 4.2 Typical Construction and Makeups 4.2.1 Typical construction 4.2.2 Makeups Problems Chapter 5 Hydraulic Control Valves 5.1 Introduction 5.2 Directional Control Valves 5.2.1 Non—return valves 5.2.2 Change valves 5.3 Pressure Control Valves 5.3.1 Relief valves 5.3.2 Pressure—reducing valves 5.3.3 Sequence valves 5.3.4 Pressure relay 5.4 Flow Rate Control Valves 5.4.1 Throttle valve 5.4.2 Speed—regulating valve 5.4.3 Relief—throttle valve 5.5 Proportional Valves and Cartridge Valves 5.5.1 Proportional valves 5.5.2 Cartridge valves Problems Chapter 6 Auxiliary Components 6.1 Accumulators 6.2 Filters 6.3 Reservoirs and Heat Exchanger 6.4 Other components Problems Chapter 7 Basic Hydraulic Circuits 7.1 Speed Control Circuits 7.1.1 Speed—regulating circuits 7.1.2 Fast—speed movement circuits 7.1.3 Speed shift circuits 7.2 Directional Control Circuits 7.2.1 Directional circuits 7.2.2 Locked circuits 7.3 Pressure Control Circuits 7.3.1 Pressure regulated circuits 7.3.2 Pressure—unloading circuits 7.3.3 Pressure—holding circuits 7.3.4 Pressure—reducing circuits 7.3.5 Supercharging circuits 7.3.6 Pressure counter—balance circuits 7.4 Multi—actuators Control Circuits Problems Chapter 8 Typical Hydraulic Transmission Systems 8.1 Hydraulic System of Power—slipway for Combined Machine Tool 8.2 Hydraulic System of YA32—500 Type Four—column Double Action Press Maehine Problem
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There are two types of hydraulic shock： ① that occursbecause of the sudden reduction of the cross—sectional area of the orifice or change of flow direction； ② that caused by the inertia of the high velocity working components during sudden braking or change of direction. Measures to reduce the hydraulic shock are as follows： （1）Prolong the time to close check and motion components.Permit also the two chambers of hydraulic actuator connecting each other at neutral position of the direction valve in order to reduce the hydraulic shock. （2）Valve orifice of motion working—piece is designed accurately to make velocity change uniformly. （3）Expand properly the diameter of pipe to make the flow velocity less than or equal to the suggested value. （4）Shorten the length of pipe to decrease the transmission velocity.Try to change the complete shock to incomplete shock. （5）Utilize rubber tube or accumulator at the point of hydraulic shock. 2.Cavitation （1）The principle and harm of cavitation Cavitation is a phenomenon that occurs if the pressure at a point is reduced far enough，hydraulic oil will vaporize and vapor cavities will form in the fluid，which will make vapor be separated from hydraulic oil and result in large number of bubbles.The pressure at which vaporization occurs is called the vapor pressure of the fluid.This vapor pressure is closely related to the hydraulic oil temperature. The phenomenon of cavitation happens easily during the suction of pump and near the valve orifice.The suction of pump will produce lower enough hydraulic pressure due to small diameter and high resistance force，or the hydraulic oil can not be filled completely into pump due to excessive high rotational velocity.On the other hand，if the valve orifice designed is too small in diameter that results in very high flow velocity，it will result in lower hydraulic pressure at the point in terms of the energy conservation.Both cases will result in cavitation. It is well known that the bubble resulted from cavitation will rupture quickly at high hydraulic pressure and cohere again into fluid accompanying the vacuum forming，high pressure hydraulic oil entrance，and it will create high temperature and shock.The bubbles full of oxygen will cause acidification and cauterization.Cauterization resulted from cavitation is called air—corrosion，which will damage the working—pieces of hydraulic machinery and shorten the life of machine.
