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Gears.  Used to transfer energy from one place to another  Rotary motion and force transferred from one part of a machine to another part  Gear Wheel:

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Presentation on theme: "Gears.  Used to transfer energy from one place to another  Rotary motion and force transferred from one part of a machine to another part  Gear Wheel:"— Presentation transcript:

1 Gears

2  Used to transfer energy from one place to another  Rotary motion and force transferred from one part of a machine to another part  Gear Wheel: a wheel with matching teeth around its edge  Gear Train: two or more gear wheels that mesh  rotary motion from one gear is transferred to another gear

3  Driving Gear (Driver): supplies the driving force in a gear train  Driven Gear (Follower): The gear wheel that the driving gear applies it’s force to  Mesh: gears must mesh, or interlock neatly as they rotate

4 Gears Can Increase Rotational Speed  A gear train can increase the rotational speed of a device  Ex. a hand mixer, bike  The driving gear is larger (has more teeth) than the driven gear so the driven gear travels faster Driving gear Driven gear

5 Gears Can Decrease Rotational Speed  Reducing gears are drive trains that decrease the rotational speed of a device so they decrease speed  Ex. bicycle, car Driving gear Driven gear

6 Gears can Change Direction  Parallel gears are the same size, so they have the same rotation speed, but they change the direction of the rotary motion  Drive wheel: clockwise; Driven wheel: counterclockwise  Ex car transmission

7  Gears can change rotary motion into straight line motion Load

8  Gears can transfer a rotary motion from one shaft to another without changing direction

9 Mechanical Advantages of Gear Trains  To calculate the increase or reduction in rotational speed calculate the ratio of the size of the driving gear to the size of the driven gear  This is called the speed ratio

10  Multiplying Gears Driving gear = 10 teeth = 2 Driven gear = 5 teeth The speed of the gear has been changed by a factor of 2, the driven gear will move twice as fast as the driving gear 10 teeth 5 teeth

11  Reducing gears Driving gear = 4 teeth = 1/2 Driven gear = 8 teeth The speed of the gear has been reduced to ½ it’s original speed 4 teeth 8 teeth

12 Sprockets  Sometimes gears are connected with a chain called a sprocket  Used to gain a multiplying effect, reduce effort or a parallel effect  The gears both rotate in the same direction  In a 10-speed bike there are 5 gears on the rear wheel and 2 gears on the pedal crank

13 Wheel and Pinion  A gear train that has 2 different sized gears  Larger gear is called a wheel  Smaller gear is called the pinion  Ex. a push lawn mover: the wheels transfer power to the blades (the pinion) which move faster than the wheels


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