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Energy, Power & Transportation Technology
Chapter 9 Mechanical Power
Use the Textbook Pages 201 224 to help answer the questions
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1. Machines can change the ______, _________, & _______ of forces in a mechanical power system, & can also change the type of motion produced.
Size, Direction,& Speed Amount, Quantity, & RPM Noise, Direction, & Speed
Pg. 201
Energy, Power & Transportation Technology 2. Machines & vehicles make use of 3 types of motion:
Reciprocating, Reverse, Forward Reciprocating, Rotary, Realistic Reciprocating, Rotary, Linear Pg. 202
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3. Machines that are made up of more than one simple machine are called ______________ machines.
Doubledup Secondary Compound Pg. 202
Energy, Power & Transportation Technology 4. The six simple machines used to control and change mechanical power are:
(W SLIP W)
Pg. 202
Energy, Power & Transportation Technology 5. A lever is a rigid bar that rotates around 1 fixed point or pivot point called the
______________.
Vulcan Fulcrum Centering Pin Pg. 203
Energy, Power & Transportation Technology 6. The 3 classes of levers are based on the position of the fulcrum,
the __________, and the input force.
Fulcrum Load Input
(a) In a firstclass lever, the fulcrum (F) is set up between the resistance (R) and the effort (M). (b) In a secondclass lever, the resistance is between the fulcrum and the effort. (c) In a thirdclass lever, the effort is between the fulcrum and the resistance.
Pg. 203
Energy, Power & Transportation Technology 7. In a 1st class lever, the fulcrum is placed ______ the input force & the load.
(seesaw)
In front of Between Behind Pg. 204
Energy, Power & Transportation Technology 8. Sketch & label a 1st class lever using arrows
for the input & output forces and a cube for the load.
Input or Effort Output Load
Fulcrum
Pg. 204
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9. In a 2nd class lever, the load is placed____ the fulcrum and the input force. (wheel barrow)
In front of Between Behind Pg. 204
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10. Sketch & label a 2nd class lever using arrows for the input & output forces and a cube for the load.
Fulcrum
Output Load
Input or Effort
Pg. 204
Energy, Power & Transportation Technology 11. In a 3rd class lever, the input force is placed ______ fulcrum and the load.
(shovel)
In front of Between Behind Pg. 204
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12. Sketch & label a 3rd class lever using arrows for the input & output forces and a cube for the load.
Input or Effort Output Load
Fulcrum
Pg. 204
Energy, Power & Transportation Technology 13.______________ consist of solid discs that rotate around a center axis.
They may be grooved to allow belts or ropes to ride around them.
Sprockets Pulleys Tires Pg. 205
Energy, Power & Transportation Technology 14. A cogged pulley that carries a chain or a cogged belt in a nonslip system
is called a ___________.
Sprocket Pulley Tire *
Energy, Power & Transportation Technology 15. A single, __________ pulley changes direction of the load
only as it relates to the input force.
Fixed Movable Round
Pg. 205
Energy, Power & Transportation Technology 16. A single, ____________ pulley changes the force required to move the load.
Fixed Movable Round
Input
Load
Pg. 205
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17. The _______ of supporting ropes or chains in a pulley system determines the mechanical advantage.
Diameter Width Number *
Energy, Power & Transportation Technology 18. Both the pulley and the _____ & _____ are based on the principle of levers.
Wheel & Axle Rack & Pinion Nut & Bolt Pg. 205
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19. The steering wheel of a vehicle resembles a: [ ] 1st class lever [ ] 2nd class lever [ ] 3rd class lever
Pg. 205
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19. The steering wheel of a vehicle resembles a: [ ] 1st class lever [ ] 2nd class lever [ ] 3rd class lever
Pg. 205
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20. Small diameter axles turning big tires resemble: [ ] 1st class levers [ ] 2nd class levers [ ] 3rd class levers
Pg. 206
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20. Small diameter axles turning big tires resemble: [ ] 1st class levers [ ] 2nd class levers [ ] 3rd class levers
Pg. 206
Energy, Power & Transportation Technology 21. An _______ ______ is a simple machine that makes use of sloping surfaces.
(ramp)
Inclined Plane Lever Pulley Pg. 207
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22. Moving an object up an inclined plane with a gentle slope requires ______ force than a steep slope.
More Less The Same
Pg. 207
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23. A ___________ is basically an inclined plane wrapped around a shaft. The finer the screw thread (slighter slope), the more holding force and the more mechanical advantage a screw will provide.
Pulley Wedge Screw Pg. 209
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24. A ___ is a simple machine made of two inclined planes placed backtoback. A wedge with slighter slope or taper will deliver more force than one with a more severe or steeper angle.
Pulley Wedge Screw Pg. 209
Energy, Power & Transportation Technology 25. A ________ is a wheel with small notches or teeth cut into
either its inner or outer edge.
Pulley Gear Sprocket Pg. 209
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26. FACT: Two or more gears meshed with each other form a gear set or a gear train.
In a gear set, the input gear is called _______ gear. The output gear is called the __________ gear.
Note: An idler gear or intermediate gear changes direction of rotation without change in gear set speed or torque
Spinner & Spun Drive & Driven Rack & Pinion
Pg. 209
Energy, Power & Transportation Technology 27. Name the types of gears show in the sets below.
Gear Word Bank:
Spur, Helical, Worm, Bevel, Rack & Pinion
Pg. 210
Energy, Power & Transportation Technology 28. Picture A is an __________ ring gear.
Picture B is a _______________ gear set
A:Planetary Gear Set Spiral Bevel Gear Set Internal Ring Gear
B:Planetary Gear Set Spiral Bevel Gear Set Internal Ring Gear
A
B
*
Energy, Power & Transportation Technology 29. Force that produces a twisting or turning effect or rotation
is referred to as ______________.
Torque Power Tension
Pg. 210
Energy, Power & Transportation Technology 30. Torque can be increased by applying more effort
or by extending the ____________ of the lever.
Diameter Length Width
Pull Here = Less Torque
Pull Here = More Torque
Pg. 212
Energy, Power & Transportation Technology 31. _______ is the rate at which output work is performed. It is abbreviated hp.
Horsepower Torque Effort Pg. 212
Energy, Power & Transportation Technology 32. ____________ hp is the maximum potential hp produced by an engine
under ideal conditions.
Frictional Brake Indicated Pg. 212
Energy, Power & Transportation Technology 33. __________ hp is the amount of hp available at the rear of the engine
under normal conditions.
Frictional Brake Indicated
Pg. 212
Energy, Power & Transportation Technology 34. _________________ hp is the amount of hp
needed to overcome friction inside the engine.
Frictional Brake Indicated
Pg. 212
Energy, Power & Transportation Technology 35. A ________ is a device that connects & disconnects a power source
from the rest of the machine.
Tensioner Clutch Transmission
Pg. 214
Energy, Power & Transportation Technology 36. __________ are long, cylindrical objects that transmit mechanical energy,
usually rotary motion.
Shafts Boards Pipes Pg. 216
Energy, Power & Transportation Technology 37. ______________ are used to support shafts and reduce friction.
(friction = bushing & antifriction = ball)
Bearings CV Joints Differentials Pg. 216
Energy, Power & Transportation Technology 38. _____ joints are placed on shafts to offer flexibility along their rotating axis.
Universal Global Wobble Pg. 216
Energy, Power & Transportation Technology 39. ____ _____ is the increased force, speed, or distance that machines provide.
Mechanical Advantage Increased Strength Torque Multiplication
Pg. 217
Energy, Power & Transportation Technology 40. Calculate M.A. by dividing __________ distance by __________ distance,
or in gear sets, by dividing # of output teeth by the # of input teeth.
Input by Output Output by Input Speed by Torque
Pg. 217
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Important Concepts, Definitions & Terms to Know
Class Notes & Priority Items to Know for Tests
Main Ideas
__________
__________
__________
Supporting Details
________________
________________
________________
TOP CRISS 2 Column Notes
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Important Concepts, Definitions & Terms to Know
Class Notes & Priority Items to Know for Tests
TOP CRISS Highlight Your Study Guides Before Tests
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Important Concepts, Definitions & Terms to Know
Class Notes & Priority Items to Know for Tests
TOP CRISS Read 3 Times
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Important Concepts, Definitions & Terms to Know
Class Notes & Priority Items to Know for Tests
TOP CRISS Ask Yourself These Questions
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• Rotary Motion: –motion in a circle
• Reciprocating Motion: – back & forth or up & down motion
• Linear Motion: – motion in a straight line
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• Sprockets, Gears, and Pulleys are all different from each other
– Sprockets are connected with chains or with cogged belts (nonslip)
– Gears drive other gears
– Pulleys are connected with Vbelts or with multiribbed belts (can slip)
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• Sprockets, Gears, and Pulleys all have ratios between each other
• 2 or more gears in mesh for a gear set or gear train
• Odd # of gears in a set: Output direction is the same as input direction
• Even # of gears in a set: Output direction is opposite of input direction
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• Indicated Horsepower: Potential under ideal conditions
• Brake Horsepower: Available at the rear (output) of the engine
• Frictional Horsepower: lost due to internal friction
• IHP – BHP = FHP
• BHP ÷ IHP = Mechanical Efficiency
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• Clutch: connects & disconnects machinery from power source
• Shaft: long cylindrical object to transmit mechanical energy (motion)
– Shafts are more often solid if they are short – Shafts are more often hollow if they are long
• Bearings: support shafts & reduce friction – Can be friction bearings like bushings – Can be antifriction bearings like needles, rollers, or ball bearings
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• Universal Joints: placed on shafts to allow flexibility
– cross & roller – rag joint – CV or constant velocity joint
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• Simple Machines (W SLIP W) – Wedge – Screw – Levers
• 1 st class • 2 nd class • 3 rd class
– Inclined Plane – Pulley – Wheel & Axle
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• Simple Machines (W SLIP W) – Wedge – Screw – Levers
• 1 st class • 2 nd class • 3 rd class
– Inclined Plane – Pulley – Wheel & Axle
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Rotation
Clockwise Counter Clockwise
“as you are facing the front of the engine”
Right Hand Left Hand
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How Many Supporting Ropes
In This Pulley System?
What’s The Mechanical Advantage
Of The System?
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Engine Motion
Reciprocating Piston
Rotary – Crankshaft
Linear – Car Moving
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Coil, Drive Plate & Driven Plate
Used as Power TakeOffs, Found in Drive Lines, Air Conditioning, and 4WD Transfer Cases
Electromagnetic Clutches
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Spur Gears Simple Design Teeth Parallel to Axis of Rotation Noisy Less Expensive
Climbing Bottoming
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Helical Gears More complex design Teeth cut on an Angle to Axis Quieter than Spur Gears Stronger than Spur Gears
Create a side thrust that needs to be addressed/protected
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Bevel Gears 90º change of motion
called “miter” gears if both are same size
generate axial thrust
generate radial thrust
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Worm Gear Set
small usually turns large
gigantic M.A. Up to 40:1
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Rack & Pinion Flat Gear is the Rack Small Gear is the Pinion
Commonly used in Steering Systems
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Planetary Gearset
Can Provide: Reductions Direct Overdrives
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Input Output
CW CCW
Gear Ratio
A mathematical comparison of either the# of teeth or the diameter or the radius used to determine mechanical advantage
Output # of Teeth ÷ Input # of Teeth = Gear Ratio
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Input Output
Output # of Teeth ÷ Input # of Teeth = Gear Ratio
10 10
10 ÷ 10 = 1
Expressed as 1:1 Gear Ratio
1:1 is a Direct Ratio
No Change in Speed Direct Speed Transfer
No Change in Torque
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Input Output
Output # of Teeth ÷ Input # of Teeth = Gear Ratio
10
40
40 ÷ 10 = 4
Expressed as 4:1 Gear Ratio
4:1 is a Reduction Ratio
Loss or Reduction of Speed
Gain of Torque
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Input
Output
Output # of Teeth ÷ Input # of Teeth = Gear Ratio
50
10
10 ÷ 50 = 0.2
Expressed as 0.2:1 Gear Ratio
0.2:1 is an Overdrive Ratio
Increase or Overdrive of Speed
Loss of Torque
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2’
12’
2’
6’
Input Distance ÷ Output Distance = Mechanical Advantage
Inclined Plane M.A.
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2’
12’
2’
6’
Input Distance ÷ Output Distance = Mechanical Advantage
Inclined Plane M.A.
12 ÷ 2 = 6 6:1 M.A.
6 ÷ 2 = 3 3:1 M.A.
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2’
12’
2’
2’
Input Distance ÷ Output Distance = Mechanical Advantage
Inclined Plane M.A.
12 ÷ 2 = 6 6:1 M.A.
2 ÷ 2 = 1 1:1 M.A.
No Gain in Force
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2’
12’
2’
6’
Input Distance ÷ Output Distance = Mechanical Advantage
Inclined Plane M.A.
6:1 M.A.
3:1 M.A.
60# 10#
60#
? #
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Input Force & Direction
Output Force & Direction
Load
Fulcrum
Bar – Will Be Split Into Effort Arm Load Arm
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9 ÷ 9 = 1 Direct Ratio 1:1
Input 8 teeth
Input 12 teeth
Output 12 teeth
Output 8 teeth
Input 9 teeth
Input 9 teeth
12 ÷ 8 = 1.5 Reduction Ratio 1.5:1
8 ÷ 12 = .66 Overdrive Ratio .66:1
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Wedge = 2 Inclined Planes backtoback
2”
2” 20”
?”
20”
Input Distance ÷ Output Distance = Mechanical Advantage
M.A. = _____ :1
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Input Diameter Output Diameter
Input Diameter ÷ Output Diameter = M.A.
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30” Crank 2” Rope Shaft
150# Bucket
M.A. = _____ How much force is needed to turn the crank?
Why does it get harder to turn the crank as the bucket comes closer to the top of the well?
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Input Diameter = 20” Output Diameter 1”
Input Diameter ÷ Output Diameter = M.A.
M.A. = ?
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On a vehicle, the axle drives the wheel & tire… M. A. becomes a number less than 1
20” Tire 2” Axle
2 ÷ 20 = .10
1/10 th the torque but… a point on the tire goes ten times farther in one turn than a point on the axle
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Input Diameter Output Diameter
Input Diameter ÷ Output Diameter = M.A.
1” ¼” or .250”
1 ÷ .25 = 4 Mechanical Advantage of Twisting a Screwdriver is 4:1
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On a vehicle, the axle drives the wheel & tire… M. A. becomes a number less than 1
40” Tire 2” Axle
2 ÷ 40 = .05
1/50 th the torque but… a point on the tire goes fifty times farther in one turn than a point on the axle Has no “get up & go”, but has better mileage
Bug with a 40” set of tires…
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On a lawn mower, the crankshaft drives the blade M. A. becomes a number less than 1
20” Blade 1” Shaft
1 ÷ 20 = .05 1/10 th the torque but… a point on the blade goes ten times farther in one turn than a point on the crankshaft ** Blade Tip Speed is limited to 19,000 ft./min ≈ 215 MPH
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We’re just inclined planes wrapped around a shaft
The Finer the Thread, the more M.A. a screw has
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Clamp with 20 threads per inch
on its screw
Clamp with 28 threads per inch
on its screw
U.S. Customary Threads
Which Has More Clamping Force?