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Forging new generations of engineers
Simple Machines
Levers
Each lever is classified by the location of the loads in relationship to the fulcrum
11stst Class Lever Class Lever
• Fulcrum is located between the effort and the resistance force
• Effort and resistance forces are applied to the lever arm in the same direction
Only class of lever that could have a MA
greater than or less than 1 v
MA =1
Effort Resistance
ResistanceEffort
MA <1
EffortResistance
MA >1
Class 1 Lever
22ndnd Class Lever Class Lever
• Fulcrum is located at one end of the lever
• Resistance force is located between the fulcrum and the effort force
• Resistance force and effort force are in opposing directions
Always has a mechanical advantage >1
Resistance
Effort
Class 2 Lever
33rdrd Class Lever Class Lever
• Fulcrum is located at one end of the lever
• Effort force is located between the fulcrum and the resistance
• Resistance force and effort force are in opposing direction
Always has a mechanical advantage < 1
Resistance
Effort
Class 3 Lever
Wheel & AxleWheel & Axle• A wheel is a lever arm that is fixed to a shaft, which is
called an axle.
• The wheel and axle move together as a simple lever to lift or to move an item by rolling.
• It is important to know within the wheel and axle system which is applying the effort and resistance force – the wheel or the axle.
CalculationsWheel & AxleWheel & Axle
E
R
DIMA =
D
Circumference = 2 π r or π d
Ǿ6 in. Ǿ20 in.
70lb
200lb
Ǿ6 in.
200lb
Ø 20 in.
AMA=E
R
F
F
70lb
Inclined PlaneCalculations
LIMA =
H
4 ft
15 ft
A flat surface set at an angle or incline with no moving parts
Able to lift objects by pushing or pulling the load
Inclined PlaneInclined Plane
Pulley
800 lb
230 lb
800 lb
IMA- Count Strands Pulling down (don’t count) Pulling up (count)
E
R
F
FAMA =
PulleyPulley• A pulley is a lever consisting of a wheel with a
groove in its rim which is used to change the direction and magnitude of a force exerted by a rope or cable.
Functions as a moving inclined plane
Tapers to a thin edge and is used for splitting, raising heavy bodies, or for tightening by being driven into something
WedgeWedge
WedgeCalculations T 3 ft
L
10 ft
LIMA =
T
An inclined plane wrapped around a cylinder, forming the path and pitch
A wheel and axle used to create rotary motion
ScrewScrew
Two Components
Properties
Change rotary motion into linear motion
Used as a threaded fastener
Large MA
Large amount of friction loss
Screw
Diameter
Effort Arm Distance – If using a wrench, effort arm distance would be the length of the wrench
Pitch
Distance between threads and linear distance traveled by 1 rotation of the screw
E2ΠrCircumferenceIMA = =
Pitch P