 |
 |
 |
| |
|
|
14.2 MOTION/FORCE TRANSMISSIONS
À p14.2.1 Gears
(|Gears are generally round or linear sets of teeth for transmitting forces or motions.
Different combinations of gears will allow conversions of forces, motions and directions.
14.2.1.1 - Spur Gears
´ ð´ 0transmit power between parallel shafts
have straight teeth parallel to axis of rotation
when two of these gears are meshed, the larger is the gear, the smaller is the pinion
14.2.1.2 - Internal Gears
´ ð´ 0transmission between parallel shafts
better meshing/more contact between gears.
14.2.1.3 - Helical Gears
´ ð´ 0can convert rotary motion to rotary motion on a non-parallel shaft.
a tooth does not suddenly engage/disengage fully, so noise and vibration are reduced.
also, more than one tooth is typically in contact, so the strength is increased.
these gears often generate longitudinal forces that require thrust bearings.
14.2.1.4 - Herringbone Gears
´ ð´ 0Looks like a helical gear, but it looks as if a second helical gear with a reverse helix has been attached.
Similar to helical gears, except that thrust bearings are not required.
14.2.1.5 - Bevel Gears
´ ð´ 0Transmit rotations to another axis perpendicular to the first.
These gears look like spur gears, but with a taper.
When the two gears are the same size they are miter gears.
for non-90° intersections, the gears are called angular bevel gears.
the rotational axes of these gears intersect.
14.2.1.6 - Hypoid Gears
´ ð´ 0Like bevel gears, but with helical teeth
the gears are often offset also (the ases of rotation do not intersect)
these gears are commonly used in the auto industry.
14.2.1.7 - Worm Gears
´ ð´ 0The worm is a helical gear with one or more threads.
The worm gear is typically a straight tooth gear that is turned by the worm.
This combination is used to convert rotation to a perpendicular rotation, and reduce the speed.
14.2.1.8 - Rack and Pinion
´ ð´ 0A rotating spur gear drives a linear rack of teeth.
this combination converts a rotation to a linear motion.
| |
|
|