Mechanisms Flashcards

1
Q

What do mechanical devices do?

A

They change an input force and movement into a desired output force and movement they can change the magnitude and direction of force

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2
Q

What can mechanisms be used for?

A

To make a force, bigger or smaller

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3
Q

What can mechanical devices be used for?

A

To produce different types of movement

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4
Q

What is linear movement?

A

Movement in a straight line in One Direction

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5
Q

What is reciprocating movement?

A

Movement in a straight line in two directions

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6
Q

What is rotary movement?

A

Rotational movement on or around an axis

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7
Q

What is oscillating movement?

A

The movement back and forth along a curved path

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8
Q

Name is six simple mechanisms

A

Inclined plane
Wedge
Screw
A lever
Wheel and axle.
Pulley

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9
Q

What is mechanical advantage?

A

A measure of the force amplification achieved by using a mechanism

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10
Q

What does MA stand for?

A

Mechanical advantage

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11
Q

What does mechanical advantage measure?

A

The ratio of the input force (effort) to the output force (load)

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12
Q

How do you calculate mechanical advantage?

A

Load divided by effort

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13
Q

What are gears? And what are they used for?

A

They are toothed wheels attached to shafts. They are used to transmit power and rotational motion around mechanical systems.

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14
Q

What do gear trains consist of?

A

Two or more interlocking gears that transmit torque and rotary motion

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15
Q

What is torque?

A

Determine force that causes rotation

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16
Q

What do the teeth of the gears do in a gear train?

A
  1. The teeth of the gears interlock
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17
Q

What is the output gear in a geartrain called?

A

The driver gear

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18
Q

What is the output gear in the geartrain called?

A

The driven gear

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19
Q

What happens if the driver gear rotates clockwise?

A

The driven gear rotate anticlockwise

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20
Q

How can the direction of rotation of the driven gear be changed?

A

By adding an idler gear

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21
Q

How does the idler gear change the direction of rotation?

A

It changes the direction of rotation, so that both the driver gear and the driven gear I’m moving in the same direction

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22
Q

Why does the size of the idler gear not matter?

A

It transfers, the movement without altering the speed of the gears

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23
Q

How do you make a faster output speed?

A

The input gear must be larger than the output gear

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24
Q

How do you create a slower output speed?

A

The input gear must be smaller than the output gear

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25
Q

How do you calculate. The number of teeth of a small gear in gear ratios?

A

by dividing the number of teeth on the last year by the number of teeth on the smaller gear

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26
Q

How do you calculate the large gear in gear ratios

A

The last year always equals one

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27
Q

What are cam mechanisms used for?

A

They used to convert rotary motion into reciprocal motion

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28
Q

What do you mechanisms consist of?

A

mechanisms consist of a cam and a follower

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29
Q

What is a cam?

A

Especially shaped piece of material attached to a rotating shaft

30
Q

How does a cam and a follower create a reciprocating motion?

A

A rod known as a follower rests on the cam and rises and falls as the cam rotates

31
Q

What depends on the shape of the cam

A

Whether the follower will either rise, fall or dwell ( Remain stationary)

32
Q

Does a cam mechanism often also include

A

1.A slide to prevent the follower from slipping.
2.A crack (handle) to manually rotate the camshaft.
3. A wheel follower to reduce friction between the cam and the follower

33
Q

List of four common cams

A

1.eccentric ( Circular)
2.pear-shaped,
3.snail
4.heart-shaped ( Constant velocity)

34
Q

How do eccentric cams work?

A

The pivot ( Rotating shaft )is positioned off centre, causing the follower to steadily rise and fall

35
Q

How does a snail cam work?

A

The follower gradually rises, and then suddenly drops. It can only rotate in One Direction.

36
Q

How does a pear-shaped cam work?

A

The follower dwells for half a turn
It then rises as the point approaches for a quarter of a term before falling for the last quarter rotation.

37
Q

How does a heart shaped cam work?

A

The follower rises, and falls, with no dwell period is said to have constant velocity

38
Q

What is a simple fixed pulley Mechanism made from

A

It is made up of a rimmed wheel and a cable which sits inside of the rimmed wheel

39
Q

What are the positives of a simple fixed pulley mechanism?

A

It provides no mechanical advantage, but it can make items easier to lift by changing the direction of force

40
Q

What can reduce the magnitude of force required to lift a load?

A

Using two or more police together in a block and tackle system

41
Q

Give an example of a block and tackle system

A

half the required input force to lift the load

42
Q

What happens in a belt and pulley system?

A

Two or more pulley are connected by about to transfer rotary, motion, and force from the driver pulley to the driven pulley

43
Q

Give an example of when a belt and pulley system is used

A

They’re used in car engines and washing machines

44
Q

As the belts need to remain taught in a belt and police system, what are they made out of?

A

They are often made of rubber to reduce the thing

45
Q

What does crossing the belts and a belt and pulley system do?

A

It changes the direction of the output movement

46
Q

In a belt and pulley system, what happens when the driver pulley is larger than the driven pulley?

A

The driven pulley will rotate faster, but the torque will be less

47
Q

In a belt and Pulley system, what happens when the driver pulley is smaller than the driven pulley?

A

The driven Polly will rotate slower, but the torque will be greater

48
Q

How can the velocity ratio between two pulleys be calculated?

A

Diameter of driven, pulley, divided by diameter of driver pulley

49
Q

What is a lever?

A

A mechanical device used to transmit and transform the effects of forces

50
Q

What is transmitted through the lever to move the load?

A

Motion and input force (effort)

51
Q

What are the three parts to a lever?

A

Effort, fulcrum/pivot,load

52
Q

What is the effort in A lever?

A

The input force exerted on the lever

53
Q

What is the fulcrum/ pivot in the lever?

A

The point around which the lever acts

54
Q

What is the load in a lever?

A

The force of the object that needs to be moved

55
Q

What are the three classes of levers?

A

First order
second order
third order

56
Q

How does the first order lever work?

A

The fulcrum is position between the Loader and the effort.

57
Q

How can the input effort required to lift the load be reduced in a first order lever?

A

by moving the fulcrum closer to the load.

58
Q

3 examples of a first order lever….

A

Scissors
Seesaw
Crowbar

59
Q

How does a second order lever work??

A

The load is positioned between the fulcrum and the effort

60
Q

How can the input effort required to lift the load be reduced?

A

By moving the load closer to the Fulcrum

61
Q

3 examples of a second order lever….

A

Bottle opener
Wheelbarrow
Nutcracker

62
Q

What Happens in a third order lever?

A

The effort this position between the Fulcrum and a load

63
Q

What do third order leavers not have compared to 1st and second order leavers

A

Mechanical advantage as the effort is closer to the fulcrum than the load. As a result, the input effort is greater than the output force.

64
Q

3 examples of a third order lever

A

Tweezers
Human arm
Fishing rod

65
Q

Name, the 3 types of linkages

A

Push and pull linkages
Bell crank linkages.
Changing magnitude of force

66
Q

What can be joined together to make linkages?

A

Leavers

67
Q

What do linkages change?

A

1.And input motion
2.force into an output motion
3.force

68
Q

What dopush/pull linkages make?

A

Creates an identical parallel motion at the output

69
Q

What kind of a push/pull linkage also be called

A

A parallel motion

70
Q

What do bell crank linkages do?

A

Change the direction of motion through 90°

71
Q

What happens in a reverse linkage? ( changing magnitude and force)

A

The fixed point (pivot)is an equal distance from the input and output leavers so the output force is equal to the input force

72
Q

In a reverse linkage, what must be done to make the output force greater than the input force

A

You must move the fixed (pivot) point closer to the output