Gear Train
A Gear Train is a combination of two or more than two gears which work
together by engaging their turning and teeth with one another. This
combination works like a single integrated system and utilize to generate
torque and power. The main objective to build a gear train is to create
larger gear ratio. In a gear train, there are multiple gears of different
sizes. For instance, the largest gear of a Gear Train is five times greater
than the smallest one. To reduce the gear speed and enhance the gear torque
in the gear system (gear train), electric motor is used. This electric motor
is mounted on the test platform and the electric motor is connected to the
driving end of each train. A large magnetic particle brake is used to
measure the magnitude of the output torque and therefore, it is connected to
the output end of the gear train.
Types of Gear Train
Simple Gear Train
This is the simplest kind of Gear Train. The teeth of the gear pair in this
type of Gear Train connecting parallel shafts. The teeth of this type of
Gear Train may either be herringbone, helical or spur. The angular velocity
is inversely related to the tooth ratio. One of the biggest disadvantage of
this type of Gear Train is that its maximum speed change ratio is only 10:1.
To get larger speed change ratio, the Gear Train size has to be enlarged.
This size enhancement may produce imbalance in wear capacities and strength
of the Gear Train.
Applications
Bicycle chain and
sprockets are simple type of Gear Trains. By pushing the paddle, the front gear is turned and it interstices with the chain links. The chain continue to move and meshing occurs continuously with the links in the rear gears that is affixed to the rear wheel. This makes the bicycle to
move.
Compound Gear Train
Compound Gear Train arrangement is preferred when large velocity is needed.
To keep the output and input shafts in a line, two keys are adjusted to a
single shaft. For this type of adjustment, equal distance from the center
for pinions and gears is chosen.
Epicyclic Gear Train
The system of Epicyclic Gear Train is alike of epicyclic gears. In this
type of system of epicyclic gear, minimum one wheel axis revolves around
another fixed axis.
Planetary Gear Train
This type of Gear train consists several components. At the center, there
is a small gear, which is called as sun gear, a big external gear which is
called as ring gear and several medium size gears which are known as planet
gears. The ring gear rolls on the planet gear and the planets revolve and
roll around the sun gear. This type of gear train has many advantages.
These are the following advantages of the Planetary Gear Train:
- The gear ratios are high.
- For automatic transmission in automobiles, these gear train are
suitable.
- Suitable in bicycles for both manual as well as automatic paddling
control.
- These are also useful for the power train between an electric motor
and a internal combustion engine.
Applications of Gear Trains
Although, the Gear Trains have many applications, but, some specific
applications of Gear Trains are as follows:
- On a clock or a watch dial, to represent the phases of moon, gear
trains are used.
- To drive a traditional two-disk lunar display off the day-of-the week
shaft of the cylinder, Gear trains are used.
Planetary Gear Trains Vs Traditional
Gear Trains
If we compare the traditional gear trains with Planetary gear train, we
will find that there are so many advantages are prevailed in the second type
of gear trains over the first type. Some of the advantages are as follows:
- In a smaller package of gears, planetary gear train provides higher
train ratio than the traditional gear train.
- By default reversion is available in Planetary gear trains, which is
not found in traditional gear trains.
- From a single unidirectional input of Planetary gear train,
bi-directional, concentric and simultaneous output can be derived.
- The above mentioned features of Planetary gear trains make them
suitable for automatic transmission in automobiles over the traditional
gear trains.
