A gear is a toothed wheel or cylinder that meshes with
another toothed component to transmit motion or to change speed or
direction. Gears are attached to a rotating shaft turned by an
external force, which is not usually illustrated in these types of
question. Two gears may be connected by touching each other
directly or by means of a chain or belt.
If gears are connected by a chain or belt then they move in the
same direction.
If the gears are touching (meshed) then adjacent gears move in
opposite directions. In this example the first and third gear will
turn in the same direction. When there are an odd number of meshed
gears then the last gear will always turn in the same direction as
the first one.
Meshed gears with an equal number of teeth will turn at the same
speed. If they have an unequal number of teeth then the gear with
the fewest teeth will turn faster. To work out how fast one is
turning with respect to the other you need to count the teeth.
Example Meshed and Belt Driven Gear Questions
1) If gear X turns clockwise at a constant speed of 10 rpm. How
does gear Y turn?
|
A |
B |
C |
D |
E |
|
anti c/w 10 rpm |
c/w
10 rpm |
c/w 5 rpm |
anti c/w 5 rpm |
c/w 20 rpm |
2) If gear X turns clockwise at a constant speed of 10 rpm. How
does gear Y turn?
|
A |
B |
C |
D |
E |
|
anti c/w 10 rpm |
c/w
10 rpm |
c/w 5 rpm |
anti c/w 5 rpm |
c/w 20 rpm |
3) If bar Y moves left a constant speed. How does bar X
move?
|
A |
B |
C |
D |
E |
|
Left, Faster |
Right, Same |
Left, Slower |
Left, Same |
Right, Slower |
4) If drive wheel X rotates clockwise at a speed of 10 rpm. How
does wheel Y turn?
|
A |
B |
C |
D |
E |
|
anti c/w faster |
c/w slower |
c/w faster |
anti c/w slower |
anti c/w same |
5) If drive wheel X rotates clockwise at a speed of 10 rpm. How
does wheel Y turn?
|
A |
B |
C |
D |
E |
|
anti c/w faster |
c/w slower |
c/w faster |
anti c/w slower |
anti c/w same |
Answers to Questions
1) A
2) D
3) D
4) B
5) E
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