Simple machines gears velocity ratios and mechanical advantage
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Simple Machines: Gears, Velocity Ratios and Mechanical Advantage. What is a simple machine?. A device which uses basic mechanisms to make work easier for the user. Example: Lifting a heavy box with a rope and pulley system

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What is a simple machine
What is a simple machine? Advantage

  • A device which uses basic mechanisms to make work easier for the user.

    • Example: Lifting a heavy box with a rope and pulley system

  • Simple machines are found in many transportation devices such as the following:

    • Cars

    • Bicycles

    • Trains


What are gears and why are they so useful
What are gears and why are they so useful? Advantage

  • Gears are toothed wheels which interlock to form simple machines.

    • The tighter the joint, the less chance of slipping

    • Gears range in size but the important number is how many teeth a gear has.


What is a gear ratio
What is a gear ratio? Advantage

  • A gear ratio is the ratio between the driver gear (the one being powered) and the driven gear (the one connected to the driver)

    • Gear Ratios are expressed as fractions and can be written a number of ways.

      • 1 to 3

      • 1/3

      • 1:3

    • Always remember that the driven gear will turn in the opposite direction of the driver gear


What is a pulley
What is a pulley? Advantage

  • A wheel with a grove carved around its circumference in which a rope or belt is placed to drive the wheel.

    • Pulleys are used in a number of applications including:

      • Elevators

      • Cranes

      • Automobiles


A pulley system
A Pulley System Advantage


Drawbacks of pulleys
Drawbacks of Pulleys Advantage

  • Pulleys work great as long as the belt which connects them is tight and both pulleys are aligned.

    • Pulleys tend to slip when too much strain is placed on the system.


How do i calculate my gear ratio
How do I calculate my gear ratio? Advantage

  • A simple equation is used to find the ratio of your gearing system

    • Number of Teeth on the Driven Gear / Number of Teeth on the Driver Gear.

    • Size of the driver pulley/ Size of the driven pulley


What is velocity ratio vr
What is Velocity Ratio (VR)? Advantage

  • When calculating for velocity or speed, it is best to have a ratio in which the driver gear is larger than the driven gear.

    • For maximum speed you should always have a larger driver gear/pulley paired with a smaller driven gear/pulley.


What is mechanical advantage ma
What is Mechanical Advantage (MA)? Advantage

  • Reciprocal of velocity ratio.

    • Mechanical advantage describes how much work can be done based on the input.

    • If my system required me to apply 50 pounds of force into the system to lift 100 pounds of weight, I have used MA.


So which do i want
So which do I want? Advantage

  • Higher velocity ratios are better when working on straight and level surfaces which are smooth.

    • Always remember that with a high VR your system will have very low power.

  • Higher mechanical advantage systems are better with inclines surfaces that are bumpy.

    • With a high MA your system will produce more power, but will move slower.


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