ELMT-1305.Intro to Hydraulicspinnacleapps.com/.../4_PascalsLaw_Basics_Hydraulics_PPT.pdf1 Intro to...
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1 I ntro to Hydraulics Pascal’s Law Hydrostatic Pressure - Results when a fluid is under pressure and its not moving. The pressure exerted on a confined fluid is transmitted undiminished in all directions and acts at right angles to the containing surfaces Exposed piston area F Confined fluid piston 2 I ntro to Hydraulics Pascal’s Law Formula: ν Where: ω P = Pressure ω F = Force ω A = Area P F A = Device used to measure pressure in a fluid power system: Pressure gauge 3 I ntro to Hydraulics Pascal’s Law Force and pressure Values Quantity U.S Customary Unit Metric (SI) Unit Force lbs Newtons (N) Area in 2 m 2 Pressure lbs/in 2 or psi N/m 2 or Pa P F A = 4 I ntro to Hydraulics Example 2-1 The piston and cylinder shown in figure 1 have a diameter (D) of 2 in and are loaded with a force (F) of 1000 lbs. What is the pressure (P) inside the cylinder? 1. Calculate Area 2. Calculate Pressure Pi X D 2 4 A = P F A = 1 psi = 6.89 kPa 14.7 psi = 1bar Fig. 1 D P P Piston Where: A = area Pi = 3.1416 D = diameter 5 I ntro to Hydraulics Example 2-2 The piston and cylinder shown in figure 1 have a diameter (D) of 1.5 in is under 500 psi of pressure. What is the force (F) applied to the system? 1. Calculate Area 2. Calculate Force Pi X D 2 4 A = F = P X A Fig. 1 D P P Piston 6 I ntro to Hydraulics Example 2-3 The piston and cylinder shown in figure 1 are required to support a force of 2500 lbs. We do not want to exceed a pressure of 1000 psi. What cylinder size is required? 4 X A A F P = Pi D = Fig. 1 D P P Piston
Transcript of ELMT-1305.Intro to Hydraulicspinnacleapps.com/.../4_PascalsLaw_Basics_Hydraulics_PPT.pdf1 Intro to...
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I ntro to Hydraulics
Pascal’s LawHydrostatic Pressure - Results when a fluid is under pressure and its not moving.
The pressure exerted on a confined fluid is transmitted undiminished in all directions and acts at right angles to the containing surfaces
Exposed piston area
F
Confined fluid
pis ton
2I ntro to Hydraulics
Pascal’s Law
Formula:
ν Where:ω P = Pressureω F = Forceω A = Area
PFA
=
Device used to measure pressure in a fluid power system:
Pressure gauge
3I ntro to Hydraulics
Pascal’s Law
Force and pressure Values
Quantity U.S Customary Unit Metric (SI) UnitForce lbs Newtons (N)Area in2 m2
Pressure lbs/in2 or psi N/m2 or Pa
PFA
=
4I ntro to Hydraulics
Example 2-1
The piston and cylinder shown in figure 1 have a diameter (D) of 2 in and are loaded with a force (F) of 1000 lbs. What is the pressure (P) inside the cylinder?
1. Calculate Area2. Calculate Pressure
Pi X D2
4A =
PF
A=
1 psi = 6.89 kPa
14.7 psi = 1bar
Fig. 1
D P P
Piston
Where:
A = area
Pi = 3.1416
D = diameter
5I ntro to Hydraulics
Example 2-2
The piston and cylinder shown in figure 1 have a diameter (D) of 1.5 in is under 500 psi of pressure. What is the force (F) applied to the system?
1. Calculate Area2. Calculate Force Pi X D2
4A =
F = P X A
Fig. 1
D P P
Piston
6I ntro to Hydraulics
Example 2-3
The piston and cylinder shown in figure 1 are required to support a force of 2500 lbs. We do not want to exceed a pressure of 1000 psi. What cylinder size is required?
4 X A
AF
P=
PiD =
Fig. 1
D P P
Piston
2
7I ntro to Hydraulics
Transmission and Multiplication of Force
One of the most useful features of fluid power is the ease with which it is able to multiply force.This is accomplished by using an output piston that is larger than the input piston.
F OUT = A OUT
A I NX F I N
8I ntro to Hydraulics
Transmission and Multiplication of Force
d in = A OUT
A I NX d out
One of the most fundamental laws of nature is that we cannot get more energy out of a system than what we put into it, so that the work done must remain constant.
If an output force is increased by a factor of 10, the distance traveled by the output piston must decrease by the same factor.
9I ntro to Hydraulics
Example 2-4 F OUT = A OUT
A I N
X F I N
Figure 1 shows an input cylinder with a diameter of 1 in and an output cylinder with a diameter of 2.5 in. A force of 250 lbs isapplied to the input cylinder. What is the output force?How far would we need to move the input cylinder to move the output cylinder 1 in?
d in = A OUT
A I N
X d out
1. Calculate the input piston Area2. Calculate the output piston Area3. Calculate the output force4. Calculate the input distance
1 in 2.5 in
250 lbs F out
10I ntro to Hydraulics
Example 2-5
The output cylinder in the previous example is required to move at 4 in/s. At what speed must the input cylinder move?
v in = A OUT
A I N
X v out
1 in 2.5 in
250 lbs F out
11I ntro to Hydraulics
T o be continued…
