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Inclined Plane, Wedge, and Screw
Simple Machines
Simple Machines
The Six Simple MachinesMechanisms that manipulate force and
distance.Lever Wheel and Axle Pulley
Inclined Plane
ScrewWedge
A flat surface set at an angle or incline with no moving parts
Able to lift objects by pushing or pulling the load
Inclined Plane
4 ft15 ft
50. lbs
20. lbR
E
FAMA =
F
50.lbAMA =
20.lb
What is the AMA of the inclined plane above?
AMA = 2.5 = 2.5:1
What is the efficiency of the inclined plane above?
2.503.75Efficiency = = 0.67 or
67%
Inclined Plane AMA
AMAIMA
• Functions as a moving inclined plane• Tapers to a thin edge• Used for splitting, raising heavy items, or tightening by expansion (being driven into something)
Wedge
Wedge IMA
E
R
DIMA =
D
DE = Distance traveled by the effort = L
DR = Distance traveled by the resistance = H
H 3.0 in.
L
10.
0 in
.
LIMA =
HWhat is the IMA of the wedge on the right?
IMA = 10.0 in. / 3.0 in. = 3.33 = 3.3:1
Wedge AMAH 3.0 in.
L 1
0.0
in
.
250. lb
700. lb700. lb
R
E
FAMA =
FWhat is the AMA of the wedge on the right? 700.lbAMA =
250.lb
AMA = 2.80 = 2.80:1
What is the efficiency of the wedge on the right?
333.3
080.2Efficiency = = 0.84 or 84%
AMAIMA
• An inclined plane wrapped around a cylinder, forming the screw’s “pitch”
• A wheel and axle used to create rotary motion
ScrewTwo Components:
Properties:• Change rotary motion into linear
motion• Used as a threaded fastener• Large amount of friction loss (is this good
or bad?)• Large MA
Pitch
Effort Arm Distance If using a wrench, effort arm distance would be the length of the wrench
Screw Identification
Diameter
Distance between threads, also the linear distance traveled in one rotation of the screw.Example: a screw has 13 threads per inch, 13 TPI for short. The pitch (distance between threads) is 1/13 of an inch.
Q: How far will a screw with 13 threads per inch advance if turned one full rotation?
A: 1/13 of a inch
Standard Thread Information
1/4 x 20 x 3.0 NC
Outside diameter of screw shaft (inches)
Pitch(TPI) Thread
description coarse or fine(Optional)
Screw Identification
Length in inches
(Optional)
M3 x 0.5 x 30
Outside diameter of screw shaft (mm)
Pitch(mm per thread)
M = Metric
Length in mm
(Optional)
Metric Thread Information
Unified Thread Information
#4 x 40 x 2.0 NC
Outside diameter of screw shaft (inches)
Pitch(TPI) Thread
description coarse or fine(Optional)
Screw Identification
Length in inches
(Optional)
• In Unified threads (measured in inches) there are numbered diameters #0 through #10
• #0 the smallest and #10 is the largest
• The major diameter in Unified Threads = 0.060" + 0.013" X (numbered diameter)
• Example: A #2 has a major diameter of 0.086"
Screw IMAE
R
DIMA =
DDE = One rotation of the effort = Circumference
DR = Linear distance traveled during one rotation = Pitch
E2πrCircumferenceIMA = =
Pitch P
1/4 20 NC
What is the IMA of the screw above if effort is applied by an 8.0in. long wrench?
32π8.0inIMA = = 1005.31 = 1.0 •10
1in20
Screw AMA
R
E
FAMA =
F
What is the AMA of the screw?
1200lbAMA =
35lbAMA = 34.29 = 34:1
What is the efficiency of the screw?
3.0510
29.34Efficiency = = 0.0341 or
3.4%
8 in.
35 lb
1/4 20 NC
1200 lb
Why is efficiency so low?
AMAIMA
Compound MachinesSimple machines working in combination to complete a task
Calculating mechanical advantage
1 2MA = ... MA MA MA
Microsoft, Inc. (2008). Clip Art. Retrieved January 10, 2008, from http://office.microsoft.com/en-us/clipart/default.aspx
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