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Wheels and Pulleys

Mindjog. 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?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

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Wheels and Pulleys

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    1. Wheels and Pulleys Introduction to Engineering and Technology Concepts

    2. Mindjog 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? 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?

    3. Wheel & Axle

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

    5. 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. What class lever is this wheel configuration?

    6. 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. What class lever is this wheel configuration?

    7. IDENTIFY ITEMS THAT APPLY THE PRINCIPLE OF THE WHEEL AND AXLE IN THEIR OPERATION. GIVE AT LEAST TWO EXAMPLES FOR EACH CLASS.

    8. Wheel Examples (2nd Class) Doorknob Screwdriver Car Climate Controls Dimmer Switch Pencil Sharpener Lamp Switch Hamster Wheel Pottery Wheel Car Jack Telescope/ Microscope Knobs Windmill/Wind Turbines Waterwheel Wheel of Fortune The Price is Right

    9. Wheel Examples (3rd Class) Carousel/Merry-Go-Round Pizza Cutter Paint Roller Fan Blade Boat or Airplane Propeller Helicopter Rotor Big Wheel™ Ferris Wheel Wheelbarrow Clock Hands Band Saw Circular Saw Blender/Grinder Bike/Car Tires Fishing Reel

    10. 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

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

    12. 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.

    13. MA = FOLLOWER ÷ DRIVER 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. Mechanical Advantage

    14. MA = FOLLOWER ÷ DRIVER Mechanical Advantage

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

    16. 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.

    17. 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

    18. 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

    19. 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.

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

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

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

    23. Pulleys

    24. Lifting Pulleys Lifting Pulleys in transmission systems Single pulley Moveable pulley Block and Tackle

    25. Single Pulley Provides change of motion, but no mechanical advantage

    26. Single Pulley The resistance arm and the effort arm are both the radius of the pulley. Since they are equal, there is no mechanical advantage.

    27. Provides change of direction and a mechanical advantage of 1:2 (at the expense of having to increase the amount of line to pull) Moveable pulley

    28. Moveable pulley A moveable pulley is a second-class pulley. The effort arm is the diameter and the resistance arm is the radius. MA = dE ÷ dR MA = 2 ÷ 1 = 2

    29. Multiple pulleys providing a greater mechanical advantage. MA is determined by the number of pulleys. Block and Tackle

    30. Block and Tackle

    31. Block and Tackle

    32. Block and Tackle

    33. 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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