1.5 - Mechanical devices

Question 1

What is a mechanism ?

Answer 1

A device that changes an input motion into a different out motion

Question 2

What is linear movement?

Answer 2

movement in a straight line

Question 3

What is reciprocating motion?

Answer 3

Movement backwards and forwards in a straight line

Question 4

What is a rotary motion?

Answer 4

movement round in a circle

Question 5

What is an oscillating motion?

Answer 5

movement swinging side to side

Question 6

What is a lever?

Answer 6

changes an input movement and force into an output movement and force.

Question 7

What does a lever move around?

Answer 7

a pivot

Question 8

What does the order of lever depend upon?

Answer 8

load, effort, fulcrum

Question 9

What is a load?

Answer 9

object being moved

Question 10

What is the fulcrum?

Answer 10

is the point where the load is pivoted

Question 11

What is the effort?

Answer 11

the force applied to move a load

Question 12

What is a first order lever?

Answer 12

has the fulcrum between the effort and load

Question 13

What is a second order leaver?

Answer 13

has the load and effort on the same side as the fulcrum

Question 14

What are linkages?

Answer 14

mechanisms that transfer force and can change the direction of movement

Question 15

What does the number and shapes of the linkage change?

Answer 15

the direction of force

Question 16

What can the position of the pivots in a linkage change?

Answer 16

size or magnitude of a force

Question 17

When the pivot is very close to the output end of the lever what happens?

Answer 17

larger force at output

Question 18

What happens in a bell crank mechanism?

Answer 18

direction of motion is turned through 90 degrees

Question 19

What is a Cam?

Answer 19

a mechanism with a cam slide and follower.When cam rotates the follower moves up and down

Question 20

What 3 things can a cam do?

Answer 20

go up, go down, stay still

Question 21

What are the 6 types of cam?

Answer 21

round, egg shaped, ellipse, eccentric, hexagon, snail

Question 22

What is a gear train?

Answer 22

a mechanism for transmitting motion and torque

Question 23

What is a torque?

Answer 23

The turning force that causes rotation

Question 24

What do gears have?

Answer 24

teeth

Question 25

If different sized gears are interlocked together what can happen?

Answer 25

They either increase or decrease the speed of rotation and the torque

Question 26

How do you work out velocity ratio of a gear train?

Answer 26

Velocity ratio = number of teeth on driven gear/ number of teeth on the driver gear

Question 27

What is friction?

Answer 27

resistance of motion when one object rubs against another

Question 28

What does the amount of friction depend on?

Answer 28

the material of which the two objects are made

Question 29

What is a co-efficient of friction?

Answer 29

the amount of friction a material has

Question 30

How can friction be reduced?

Answer 30

using low co-efficient of friction material or lubrication

Question 31

What is a rack and pinion mechanism?

Answer 31

can turn rotary motion to linear motion or vice versa

Question 32

What does a crank and slider mechanism do?

Answer 32

turns linear motion to rotary motion or vice versa

Question 33

How do you work out load?

Answer 33

mechanical advantage X effort

Question 34

What is a chain and sprocket mechanism?

Answer 34

transfers rotary motion into rotary motion elsewhere in a machine

Question 35

What is a sprocket?

Answer 35

a toothed wheel and a chain is made up of links that can pivot and go over the teeth on a sprocket

Question 36

How do you work out the velocity ratio of a sprocket and chain system?

Answer 36

number of teeth on the driven sprocket / number of teeth on driver sprocket

Question 37

What is a pulley system?

Answer 37

transmits rotary motion to rotary motion in machines

Question 38

What will two pulleys connected together on a flexible belt transmit?

Answer 38

rotary motion and torque

Question 39

How do you work out the velocity ratio of a pulley system?

Answer 39

diameter of driven pulley / diameter of driver pulley