Simple Machines Inclined Plane Wedge and Screw

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Inclined Plane, Wedge, and Screw
The Six Simple Machines
Mechanisms that manipulate force and distance.
Lever
Wheel and Axle
Pulley
Inclined Plane
Wedge
Screw
A flat surface set at an angle or incline with no
moving parts
Able to lift objects by pushing or pulling the load
FR
AMA =
FE
4 ft
What is the AMA of the inclined plane above?
50.lb
AMA =
20.lb
AMA = 2.5 = 2.5:1
What is the efficiency of the inclined plane above?
2.50
AMA
= 0.67 or 67%

Efficiency =
3.75
IMA
• 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)
DE = Distance traveled by the effort = L
10.0 in.
L
DE
IMA =
DR
H 3.0 in.
DR = Distance traveled by the resistance = H
L
IMA =
H
What is the IMA of the wedge on the right?
IMA = 10.0 in. / 3.0 in. = 3.33 = 3.3:1
250. lb
What is the AMA of the
wedge on the right?
700.lb
AMA =
250.lb
L 10.0 in.
FR
AMA =
FE
H 3.0 in.
AMA = 2.80 = 2.80:1
What is the efficiency of the wedge
on the right?
AMA 2.800
= 0.84 or 84%

Efficiency =
3.333
IMA
Two Components:
• An inclined plane wrapped
around a cylinder, forming
the screw’s “pitch”
• A wheel and axle used to
create rotary motion
Properties:
•
•
•
•
Change rotary motion into linear motion
Used as a threaded fastener
Large amount of friction loss (is this good or bad?)
Large MA
Effort Arm Distance
If using a wrench, effort arm distance
would be the length of the wrench
Pitch
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
Diameter
Standard Thread Information
1/4 x 20 x 3.0 NC
Pitch
Length in
(TPI)
Outside
inches
diameter of
(Optional)
screw shaft
(inches)
Thread
description
coarse or fine
(Optional)
Metric Thread Information
M3 x 0.5 x 30
M = Metric
Outside
Pitch
diameter of (mm per
screw shaft thread)
(mm)
Length in
mm
(Optional)
Unified Thread Information
#4 x 40 x 2.0 NC
Pitch
Length in
(TPI)
Outside
inches
diameter of
(Optional)
screw shaft
(inches)
Thread
description
coarse or fine
(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"
DE
IMA =
DR
1/4 20 NC
DE = One rotation of the effort = Circumference
DR = Linear distance traveled during one rotation = Pitch
Circumference 2πrE
IMA =
=
Pitch
P
What is the IMA of the screw above if effort is applied
by an 8.0in. long wrench?
2π8.0in
IMA =
= 1005.31 = 1.0 •103
1in
20
FR
AMA =
FE
1/4 20 NC
35 lb
What is the AMA of the screw?
1200lb
AMA =
35lb
AMA = 34.29 = 34:1
1200 lb
What is the efficiency of the screw?
AMA

Efficiency =
IMA
34.29
= 0.0341 or 3.4%
1005.3
Why is efficiency so low?
Simple machines working in combination
to complete a task
Calculating mechanical advantage
MA = MA1   MA2   MA...
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