1st Edition

# Hydraulic Power System Analysis

By Arthur Akers, Max Gassman, Richard Smith Copyright 2006
400 Pages 137 B/W Illustrations
by CRC Press

400 Pages
by CRC Press

Also available as eBook on:

The excitement and the glitz of mechatronics has shifted the engineering community’s attention away from fluid power systems in recent years. However, fluid power still remains advantageous in many applications compared to electrical or mechanical power transmission methods. Designers are left with few practical resources to help in the design and analysis of fluid power systems, especially when approaching fluid power for the first time.

Helping you overcome these hurdles, Hydraulic Power System Analysis demonstrates modern computer-aided analytical techniques used to model nonlinear, dynamic fluid power systems. Following an overview of fluid power, the authors examine various relevant fluid properties, energy calculations, and steady state and dynamic analysis along with a review of automatic control theory. Turning to modeling, the next few chapters address valves and motors and then apply dynamic modeling to examples relating to pumps, hydrostatic transmissions, and valves. The book includes a unique chapter showing how to combine flow resistance equations with the differential equations governing dynamic system performance. The final chapter translates electrical circuit theory concepts to noise attenuation in fluid power systems.

Illustrated with many equations, practical computer modeling examples, and exercises, Hydraulic Power System Analysis provides a much-needed modernization of dynamic modeling for fluid power systems using powerful computational tools.

Introduction
What Is Fluid Power?
A Brief History of Fluid Power
Fluid Power Applications, Present and Future
Advantages of Using Fluid Power Systems
A Probable Future Development
Properties of Fluids and Their Units
Basic Properties of Fluids
Compressibility of Liquids
Rationale for Model Development
Source of Equations
Conservation of Flow and Energy
Friction Losses in Pipes and Fittings
Basic Component Equations
Worked Examples
Discussion
Dynamic Modeling
Development of Analytical Methods
Software Options
Dynamic Effects
Worked Examples
Modeling Hints and Tips
Discussion
Linear Systems Analysis
Introduction
Linear Systems
The Laplace Transform
Inversion, the Heaviside Expansion Method
Stability
Block Diagrams
Spring-Mass-Damper Time Response to Unit Step Force
Time Constant
Frequency Response and Feedback
Introduction
Mathematics of Frequency Response
Frequency Response Diagrams
Using Frequency Response to Find Controller Gain
Summary
Valves and Their Uses
Introduction
Directional Control Valves
Special Directional Control Valves, Regeneration
Flapper Nozzle Valve
Flow Control Elements
Relief Valves
Pressure Reducing Valve
Pressure Sequencing Valve
Counterbalance Valve
Flow Regulator Valve
Pumps and Motors
Configuration of Pumps and Motors
Pump and Motor Analysis
Leakage
Form of Characteristic Curves
Axial Piston Pumps and Motors
Pressure During a Transition
Torque Affected by Pressure Transition — Axial Piston Pump
Torque and Flow Variation with Angle for Multicylinder Pumps
Hydrostatic Transmissions
Introduction
Performance Envelope
Hydrostatic Transmission Physical Features
Hydrostatic Transmission Dynamic Analysis
Pressure Regulating Valve
Purpose of Valve
Operation of Valve
Mathematical Model of Valve
Effect of Damping
Valve Model Expansion
Basic Valve Model
Model Expansion
An Assessment of Modeling
Flow Division
Introduction
The Hydraulic Ohm Method
Brief Review of DC Electrical Circuit Analysis
Fluid Power Circuit Basic Relationships
Consolidation of Fluid Power Resistances
Application to Unsteady State Flow
Conclusions
Noise Control
Introduction
Discussion of Method
Mathematical Model
Effect of Entrained Air in Fluid
Further Discussion of the Mathematical Model
Other Methods of Noise Control
Damping Methods
Index

### Biography

Arthur Akers, Max Gassman, Richard Smith