Mechanisms

Question 1

What is a lever?

Answer 1

A lever is a long, rigid object with a pivot somewhere along its length. The pivot is sometimes called the fulcrum

Question 2

Class 2 levers

Answer 2

Class 2 levers have the load in the middle and the effort and fulcrum on the outside e.g a gardener lifting a wheel barrow

Question 3

Class 3 levers

Answer 3

Class 3 levers have the fulcrum at one end, the load at the other and the effort somewhere in the middle e.g a fisherman catching a fish

Question 4

Class 1 levers

Answer 4

Class 1 levers have the load at one end the effort at the other and the fulcrum in the middle e.g a work man pushing a trolley

Question 5

Rack and pinion

Answer 5

The ‘pinion’ is the normal round gear and the ‘rack’ is straight or flat. The pinion rotates and moves the rack in a straight line another way of saying it is “rotary motion” changes to “linear motion”

Question 6

Worm and wheel

Answer 6

The arrangement of gears seen left is called a worm. Which is like a screw and thread and only has 1 tooth. A worm wheel is like a normal gear or spur gear.

Question 7

Beval gears

Answer 7

Beval gears can be used to change the direction of drive in a gear system by 90°. A good example is seen as the main mechanism for a hand drill as the handle of the drill is turned in a vertical direction the beval gears change the rotation of the church to a horizontal rotation.

Question 8

Bund facer

Answer 8

The hand facer is used to smooth materials such as wood / plastics used to remove a small amount of waste material. It is. It’s a dangerous machine if safety is ignored.

Question 9

Flat hand file is…..

Answer 9

Rectangular in section and are the most common file. The safe edge of the file has no teeth this is extremely useful when filing corners. This safe edge is placed into the corner because it is smooth and dose not damage the surface material.

Question 10

Half round file

Answer 10

Used for filing curved surfaces. A normal hand file with its flat cutting edges is unsuitable for filing concave surfaces.

Question 11

Round

Answer 11

Used for filing curved surfaces with holes

Question 12

Smooth cut and second cut

Answer 12

Files are often graded according to the roughness/ smoothness of the cut.
Very little lines means it’s a rough file second cut with have a lot more lines but the file with the most lines close together is for a smooth finish

Question 13

Butt joint

Answer 13

It’s when bits of wood are connected using nails.

Question 14

Dowel joint

Answer 14

When dowels are used to connect wood together

Question 15

Finger joint

Answer 15

The woods are cut like boxes in a flat line but alternating from side to side

Question 16

Dove tail joint

Answer 16

When it’s like the fingers joint but at angles

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Question 17

Where dose the strength of joints come from

Answer 17

The strength of a joint comes from the increase of surface area that the PVA glue can act on

Question 18

What dose a cam do?

Answer 18

A cam changes input Motion which is usually rotary motion, to a reciprocating motion of the follower they are found in many machines and toys. A cam has two parts the follower and the cam profile

Question 19

Key frases of the cam

Answer 19

One cycle- one rotation of cam
The rise. - part of cam that causes the follower to rise
Dwell. - when the cam rotate but the follower doesn’t rise or fall

Question 20

What is the follower

Answer 20

There are different types of follower but they all slide or roll on the edge of the cam.

Question 21

Name the for types of followers.

Answer 21

Flat follower.
Point/knife follower
Roller follower
Offset follower

Question 22

Cam profiles

Answer 22

Cams can be shaped in any number of ways and this is determined by the way the follower is to move. The shape of the cam is called the profile.

Question 23

Pear

Answer 23

Pear-shaped cams are used on the shafts of cars. The follower remains motionless for about half of the cycle of the cam, and during the second half it rises and falls

Question 24

Eccentric cam

Answer 24

Circular cam, or a eccentric cams produce, a smooth motion these cams are used in steam engines

Question 25

Heart shaped cams

Answer 25

Heart shaped cams allow the follower to rise and fall with ‘uniform’ velocity

Question 26

Drop (snail)

Answer 26

It gives a drop and rise motion

Question 27

What are the three main types of followers

Answer 27

Flat
Knife
Roller

Question 28

What is a flat follower

Answer 28

Has a large flat surface on the base. Used when necessary that it follows a very precise cam profile. The cam will move in rotary motion while the follower will move in a reciprocating motion

Question 29

What is a knife follower

Answer 29

Mainly used with heart shaped cams as they can follow very detailed profile. They normally have a hardened steel tip and are designed to go down into the right curves of the cams

Question 30

What are roller followers

Answer 30

This type of follower has a small roller bearing at the end they are useful for reducing friction and wear between cam and the follower

Question 31

The input

Answer 31

The input is usually a force and initiates the process

Question 32

The process

Answer 32

The process will change the magnitude or direction of the force

Question 33

Output

Answer 33

The output is what preforms a desired task