Inclined Plane, Wedge, and Screw

Lever

The Six Simple Machines

Mechanisms that manipulate force and distance.

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

AMA = F

R

F

E What is the AMA of the inclined plane above?

AMA = 50.lb

20.lb

AMA = 2.5 = 2.5:1 What is the efficiency of the inclined plane above?

Efficiency = AMA IMA 

2.50

3.75

= 0.67 or 67% 4 ft

• 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)

IMA = D

E

D

R D E = Distance traveled by the effort = L D R = Distance traveled by the resistance = H

IMA = L H

What is the IMA of the wedge on the right?

IMA = 10.0 in. / 3.0 in. = 3.33 =

3.3:1

H 3.0 in.

250. lb

AMA = F

R

F

E What is the AMA of the wedge on the right?

AMA = 700.lb

250.lb

H 3.0 in. AMA = 2.80 = 2.80:1 What is the efficiency of the wedge on the right?

Efficiency = AMA IMA  2 .

80 0 3 .

3 33 = 0.84 or 84%

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 Outside diameter of (TPI) screw shaft (inches) Length in inches (Optional) Thread description coarse or fine (Optional) Metric Thread Information M3 x 0.5 x 30 M = Metric Outside diameter of screw shaft (mm) Pitch (mm per thread) Length in mm (Optional)

Unified Thread Information #4 x 40 x 2.0 NC Pitch Outside diameter of (TPI) screw shaft (inches) Length in inches (Optional) 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"

1/4 20 NC D E

IMA = D

E

D

R = One rotation of the effort = Circumference D R = Linear distance traveled during one rotation = Pitch IMA = Circumference Pitch = 2πr E P What is the IMA of the screw above if effort is applied by an 8.0in. long wrench?

IMA = 2π8.0in

1in = 1005.31 = 1.0 •10

3

20

AMA = F

R

F

E 1/4 20 NC

35 lb

What is the AMA of the screw?

AMA = 1200lb 35lb

AMA = 34.29 = 34:1 1200 lb What is the efficiency of the screw?

Efficiency =

AMA IMA



34 10 .

29 05 .

3

= 0.0341 or 3.4% Why is efficiency so low?

Simple machines working in combination to complete a task Calculating mechanical advantage MA =

MA 2 MA

...



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