# Wheel-and-Axle and Pulley - Dulaney High School Home Page by wanghonghx

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Introduction to Engineering and
Technology Concepts
Mindjog

1. How much effort will be needed to lift a
100 pound load if distance to effort is
five feet and distance to resistance is
one foot?
2. How much effort will be needed to lift a
48 pound load if distance to effort is
two feet and distance to resistance is
8 feet?
Wheel & Axle
Wheel and Axle

The Wheel and Axle work off the same
principle as the lever.

Wheel diameter = 8
Axle diameter = 1
Produce an 8/1 MA
Wheel and Axle
If the effort (input) is applied to the wheel, the axle
is the resistance (output).
– This will produce a mechanical advantage
equal to the size ratio of the wheel as
compared to the axle.

Wheel diameter = 8
R     E    Axle diameter = 1
Produces an MA of 8
What class lever is this wheel configuration?
Wheel and Axle
If the effort (input) is applied to the axle, the
wheel is the resistance (output).
– This will create an increase in output
distance but it will take more effort to turn.

Wheel diameter = 8
E     R
Axle diameter = 1
Produces an MA of 1/8

What class lever is this wheel configuration?
IDENTIFY ITEMS THAT
APPLY THE PRINCIPLE OF
THE WHEEL AND AXLE IN
THEIR OPERATION. GIVE AT
LEAST TWO EXAMPLES FOR
EACH CLASS.
Wheel Examples (2nd Class)

Doorknob           Car Jack
Screwdriver        Telescope/
Car Climate        Microscope Knobs
Controls           Windmill/Wind
Dimmer Switch      Turbines
Pencil Sharpener   Waterwheel
Lamp Switch        Wheel of Fortune
Hamster Wheel      The Price is Right
Pottery Wheel
Wheel Examples (3rd Class)

Ferris Wheel      Carousel/Merry-Go-
Wheelbarrow       Round
Clock Hands       Pizza Cutter
Band Saw          Paint Roller
Circular Saw      Fan Blade
Blender/Grinder   Boat or Airplane
Bike/Car Tires    Propeller
Fishing Reel      Helicopter Rotor
Big Wheel™
Mechanical Transmission

A device which accomplishes one, or
more, of the following:
– Transfer motion from one point to another
– Increase output speed OR force
– Change direction of motion
– Change type of motion
Motion

Four types of motion:
– LINEAR – Straight line, one direction
– RECIPROCATING – straight line, back
and forth
– ROTATIONAL – Circular
– OSCILLATING - Swinging
Pulleys

A pulley is basically a wheel with a groove in
the circumference of the wheel, with a belt or
cable being fed around the groove.
Pulleys create a mechanical advantage by
connecting a small input drive pulley to a
larger follower with a belt.

Driver                                Follower
(Effort)                              (Resistance)
MA = FOLLOWER ÷ DRIVER

Driver                                Follower
1mm                                    4mm

The Pulley Drive Train above produces an
MA of 4. This means 10 lbs of input torque
will create 40 lbs output, but the driver must
rotate 4 times to rotate output 1 time. Speed
is reduced by 4.
MA = FOLLOWER ÷ DRIVER

Driver                        Follower
3mm                            9mm

Driver                            Follower
2mm                                14mm
Increasing Speed

Increase the speed of the output by
using a larger driver gear and a smaller
follower gear. Speed increases and
power decreases.

Driver                            Follower
4mm                                1mm
Compound Drive Pulley Trains
• A Compound Drive Pulley Train has pairs of
pulleys working in combination, with the
follower of one pulley sharing the same axle
as the driver of the next sequential pulley
train.
Compound Drive Pulley Trains
MA = (FOLLOWER 1 X FOLLOWER 2) ÷
(DRIVER 1 x DRIVER 2)

– Driver 1 = 2mm   Follower 1 = 8mm
– Driver 2 = 3mm   Follower 2 = 9mm
Compound Drive Pulley Trains
MA = (FOLLOWER 1 X FOLLOWER 2) ÷
(DRIVER 1 x DRIVER 2)

– Driver 1 = 3mm   Follower 1 = 9mm
– Driver 2 = 2mm   Follower 2 = 14mm
Problem

Sketch the following two pulley
trains:
– A: Simple pulley train with belt
wrapped so both pulleys rotate in
same direction.
– B. Simple pulley train with belt
wrapped so both pulleys rotate in
opposite direction.
Solution

A: Simple pulley train with belt wrapped
so both pulleys rotate in same direction.
Solution

B. Simple pulley train with belt wrapped
so both pulleys rotate in opposite
direction.
Problem

Calculate the mechanical
advantage of the compound pulley
drive train model.
– Show your work.
– Small Pulley Diameter = 25mm
– Large Pulley Diameter = 100mm
Pulleys
Lifting Pulleys

Lifting Pulleys in transmission
systems
– Single pulley
– Moveable pulley
– Block and Tackle
Single Pulley

Provides change of
motion, but no
mechanical
100 lbs       100 lbs

100 lbs

100 lbs
Single Pulley

The resistance arm
and the effort arm are
both the radius of the
pulley. Since they are
equal, there is no
Moveable pulley
Provides change of direction and a
mechanical advantage of 1:2 (at the
expense of having to increase the amount
of line to pull)

50 lbs        50 lbs

50 lbs

50 lbs
100 lbs
100 lbs
Moveable pulley

A moveable pulley is
a second-class
pulley.
The effort arm is the
diameter and the
resistance arm is the
MA = dE ÷ dR
MA = 2 ÷ 1 = 2
Block and Tackle
Multiple pulleys providing a greater
MA is determined by the number of pulleys.

25 lbs
25 lbs       25 lbs

25 lbs

25 lbs
100 lbs
100 lbs
Block and Tackle

Gun Tackle        Luff Tackle
Block and Tackle
Block and Tackle
Review

Give real-world example of each of the
following pulleys.
– Force Multiplier
– Speed Multiplier
– Direction Changer
Give one example of a simple machine
or transmission that changes output
motion. Identify both input and output
motions.

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