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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