# 1.5 - Mechanical devices Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is a mechanism ?

A

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

2
Q

What is linear movement?

A

movement in a straight line

3
Q

What is reciprocating motion?

A

Movement backwards and forwards in a straight line

4
Q

What is a rotary motion?

A

movement round in a circle

5
Q

What is an oscillating motion?

A

movement swinging side to side

6
Q

What is a lever?

A

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

7
Q

What does a lever move around?

A

a pivot

8
Q

What does the order of lever depend upon?

A

9
Q

A

object being moved

10
Q

What is the fulcrum?

A

is the point where the load is pivoted

11
Q

What is the effort?

A

the force applied to move a load

12
Q

What is a first order lever?

A

has the fulcrum between the effort and load

13
Q

What is a second order leaver?

A

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

14
Q

A

mechanisms that transfer force and can change the direction of movement

15
Q

What does the number and shapes of the linkage change?

A

the direction of force

16
Q

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

A

size or magnitude of a force

17
Q

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

A

larger force at output

18
Q

What happens in a bell crank mechanism?

A

direction of motion is turned through 90 degrees

19
Q

What is a Cam?

A

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

20
Q

What 3 things can a cam do?

A

go up, go down, stay still

21
Q

What are the 6 types of cam?

A

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

22
Q

What is a gear train?

A

a mechanism for transmitting motion and torque

23
Q

What is a torque?

A

The turning force that causes rotation

24
Q

What do gears have?

A

teeth

25
Q

If different sized gears are interlocked together what can happen?

A

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

26
Q

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

A

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

27
Q

What is friction?

A

resistance of motion when one object rubs against another

28
Q

What does the amount of friction depend on?

A

the material of which the two objects are made

29
Q

What is a co-efficient of friction?

A

the amount of friction a material has

30
Q

How can friction be reduced?

A

using low co-efficient of friction material or lubrication

31
Q

What is a rack and pinion mechanism?

A

can turn rotary motion to linear motion or vice versa

32
Q

What does a crank and slider mechanism do?

A

turns linear motion to rotary motion or vice versa

33
Q

How do you work out load?

A

34
Q

What is a chain and sprocket mechanism?

A

transfers rotary motion into rotary motion elsewhere in a machine

35
Q

What is a sprocket?

A

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

36
Q

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

A

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

37
Q

What is a pulley system?

A

transmits rotary motion to rotary motion in machines

38
Q

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

A

rotary motion and torque

39
Q

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

A

diameter of driven pulley / diameter of driver pulley