1. Mechanisms Get your notebook please- we are taking a few notes first
Gateway To Technology®
Unit 2 – Lesson 2.2 – Mechanical Systems
Mechanisms
Get your notebook please- we are taking a few notes first

2. Mechanisms
Gateway To Technology®
Unit 2 – Lesson 2.2 – Mechanical Systems
What is a Mechanism?
A mechanism is the part of a machine which contains two or more pieces arranged so that the motion of one compels the motion of the others.
Generally used to:
Change the direction of movement
Change the type of movement
Change the speed of movement
Change the amount of torque or force available to do work

3. Mechanisms - Change Direction
Meshed gears in a gear train always turn in opposite directions
The flow of power is reversible only if you can make the input shaft turn by turning the output shaft

4. Mechanisms - Change Movement
Gateway To Technology®
Unit 2 – Lesson 2.2 – Mechanical Systems
Mechanisms - Change Movement
Rotary
Oscillating
Linear
Reciprocating

5. Mechanisms - Change Speed
Gear ratios compare the output (or driven gear) to the input (or drive gear)
If the output gear is larger than the input gear the speed will decrease
If the output gear is smaller than the input gear the speed will increase.

6. Mechanisms – Change Force or Torque
A force is a push or pull in a straight line.
Torque is a push or pull in a circular direction.

7. Mechanisms – Torque vs Speed
More torque = easier to move = less speed
(like when going up hill)
More speed = harder to move
= less torque
(like when going on straight away or down a hill)

8. Gear Ratios
Gear ratios compare the output (or driven gear) to the input (or drive gear)
INPUT
_______ = Gear Ratio
OUTPUT

9. Simple Gear Train 1. Input and Output Shafts parallel
Mechanisms
Gateway To Technology®
Unit 2 – Lesson 2.2 – Mechanical Systems
Simple Gear Train
1. Input and Output Shafts parallel
3. A - Speed is constant
4. B – Speed is increased
5. A - Torque is constant
6. B – Torque is decreased
7. A - Ratio 1:1
8. B - Ratio
36 teeth:60 teeth or 3:5
9. Flow of Power
reversible
10. Gear direction – opposite A.
Driven
Drive B.
Driven
Drive gear is on the input shaft, driven gear is on the output shaft.
Drive

10. Where Do You Find a Simple Gear Train?
Mechanisms
Gateway To Technology®
Unit 2 – Lesson 2.2 – Mechanical Systems
Where Do You Find a Simple Gear Train?
11. Found in:
Watch
Sewing Machine
Motor
Watch gears
Two meshed gears will rotate in opposite directions.

11. Simple Gear Train with Idler
Mechanisms
Gateway To Technology®
Unit 2 – Lesson 2.2 – Mechanical Systems
Simple Gear Train with Idler
1. Input and Output Shafts parallel
3. Speed is constant
4. Torque is constant
5. Ratio 1:1
6. Flow of Power
reversible
7. Input and Output Gears same direction
Without Idler Gear different direction
Driven
Drive
Idler

12. Where Do You Find a Simple Gear Train with Idler?
Mechanisms
Gateway To Technology®
Unit 2 – Lesson 2.2 – Mechanical Systems
Where Do You Find a Simple Gear Train with Idler?
Two meshed gears will rotate in opposite directions.
An Idler Gear allows the drive and driven gears to rotate in the same direction.
8. Found in - Paper Transport Rollers