COURSE INTRODUCTION

• Welcome to the IIT Basic Hydraulics Interactive Computer Based Training Course.
• Purpose: To provide a broad understanding of important hydraulic concepts.
• Goals upon completion:   - Understanding various basic physics laws as they apply to fluid power.   - Understanding schematics and system design.   - Studying the components of a hydraulic system and their functions and interactions.
• Navigation: Select topics from the course menu.   - Recommended progression: Start with Fluid Power Physics and continue in order.
• Interactive nature: Study at your own pace and review materials periodically after course completion.
• Manual supplement for the course includes:   - Notes   - Additional applications   - Expanded formulas   - Quiz questions
• Manual available on the Web Portal: www.fluidpowerzone.com
• Note: Quiz answers found in the quiz sections on the CD. A Post Test is provided online.
• Copyright © 2000 by Interactive Industrial Training

FLUID POWER PHYSICS

Introduction

• Goals after completion: Better understanding of basic physics principles governing fluid power.
• These principles provide a solid foundation for further learning in fluid power.

Energy

• Definition: Fluid power as a method of transferring energy.   - Energy transferred from a prime mover (input source) to an actuator (output device).   - Transfer methods can vary in efficiency but can yield optimal work control when applied correctly.
• Energy: The ability to do work.   - Work: Defined as force through distance.   - Example: Moving 1000 pounds a distance of 2 feet equals 2000 foot-pounds of work.   - Units: Work is measured in foot-pounds.
• Power: The rate of doing work, defined as work over time.   - Example: Lifting 1000 pounds 2 feet in 2 seconds yields 1000 units of power, calculated as     $\frac{1000 imes 2}{2 ext{ seconds}}$.   - Horsepower (hp) is often used to measure power.

NOTES

Work and Power Definitions

• Work (in lbs) = Force (lbs) x Distance (in)
• Power = Force x Distance / Time
• Important Note: Systems are generally less than 10% efficient; efficiency factors must be considered in calculations.
• Example Calculation: Input horsepower = $\frac{10 ext{ gpm} imes 1500 ext{ psi}}{1714} = 8.75 ext{ hp}$; thus, rounded to 10 hp, considering efficiency.
• Rule of Thumb: 1 gpm at 1500 psi = 1.0 input hp.

Horsepower Calculation

• Hydraulic horsepower formula:   $ext{Horsepower} = \frac{ ext{gpm} imes ext{psi}}{1714}$
• Example of lifting weight:   - Lifting 10,000 pounds a distance of 1 foot in 2 seconds with a flow rate of 10 gpm at 1500 psi gives a theoretical requirement of 8.75 hp.

Heat

• Law of Conservation of Energy: Energy cannot be created or destroyed, only transformed.
• Hydraulics can convert unused energy into heat (e.g., through resistance in a relief valve).

Other Important Calculations

1. Torque: Defined as twisting force, measured in foot-pounds (e.g., 10 foot-pounds from applying 10 pounds of force to a wrench). Applies to hydraulic motors rated by specific torque values.
2. Quiz Questions:    1. Work accomplished by moving 500 lbs 2 feet is 1000 foot-pounds. (True/False?)    2. Power is defined as the rate of doing work. (True/False?)    3. Wasted energy in a hydraulic system is destroyed. (True/False?)   

Additional Notes on Horsepower

• 1 hp = 33,000 ft • lbs/min = 746 W = 42.4 Btu/min.

Formulas

• Energy Formulas:   - 1 kW = 1.3 hp   - 1 hp = 550 ft • lbs/s   - $ext{Hydraulic hp} = \frac{ ext{gpm} imes ext{psi}}{1714}$   - Torque (in • lbs) = $\frac{ ext{psi} imes ext{disp (in}^3/ ext{rev})}{6.28}$   - $ext{Torque (in lbs)} = \frac{ ext{hp} imes 63025}{ ext{rpm}}$   - $ext{Btu (per hour)} = ext{Δpsi} imes ext{gpm} imes 1.5$
• To determine the volume (in3) of a piston moving a distance, use:   - Volume = Piston Area (in2) x Stroke (in)
    - Cylinder Speed (ft/min) = $\frac{ ext{gpm} imes 19.25}{ ext{Effective Area (in2)}}$   - Flow (theoretical) = $ext{Pump rpm} imes ext{in}^3/ ext{rev} imes \frac{1}{231}$

Flow Principles

1. Flow in a hydraulic system:    - Produced from a positive displacement pump (unlike a centrifugal pump).

Three Key Principles of Flow:

• Principle 1: Flow makes it go.   - An actuator must be supplied with flow to operate.
• Principle 2: Rate of flow determines speed.   - Usually measured in gallons per minute (gpm).
• Principle 3: Changes in actuator volume displacement alter the flow rate and, consequently, speed.

Quiz Questions on Flow Concepts

1. Changes to flow rate do not affect actuator speed. (True/False?)
2. A larger diameter cylinder will affect its speed on extension/retraction. (True/False?)

Torque and Rotational Relationships

• Torque is crucial in projecting hydraulic motors' performance and efficiency at given pressures.
• Example: Torque (in • lbs) = $63025 imes ext{hp} / ext{rpm}$

Summary of Key Concepts

• Managing energy transfer, flow, and pressure control in hydraulic systems is foundational for understanding hydraulics.
• Essential calculations underpin hydraulic performance, and understanding component interactions is critical for optimizing system design.