4923803
1_Differential
- What is a differential?
- 1. A differential is a particular type of simple planetary gear train that has the property that the angular
velocity of its carrier is the average of the angular velocities of its sun and annular gears
- 2. In automobiles and other
wheeled vehicles, the
differential allows the outer
drive wheel to rotate faster
than the inner drive wheel
during a turn.
- 3. This is necessary when the vehicle turns, making the wheel that is traveling around the
outside of the turning curve roll farther and faster than the other. The average of the
rotational speed of the two driving wheels equals the input rotational speed of the drive
shaft. An increase in the speed of one wheel is balanced by a decrease in the speed of the
other.
- 1. A differential is a particular type of simple planetary gear train that has the property that the angular
velocity of its carrier is the average of the angular velocities of its sun and annular gears
- Who invented it?
- There are many claims to the invention of the differential gear but it is
possible that it was known, at least in some places, in ancient times.
Some historical milestones of the differential include
- 30 BC–20 BC: Differential gear
systems possibly used in China
- 658, 666 AD: two Chinese Buddhist monks and
engineers create south-pointing chariots for
Emperor Tenji of Japan.
- 1720: Joseph Williamson uses a differential gear in a clock
- 1810: Rudolph Ackermann of Germany invents a
four-wheel steering system for carriages, which some later
writers mistakenly report as a differential.
- 1832: Richard Roberts of England patents 'gear
of compensation', a differential for road
locomotives.
- 1958: Vernon Gleasman patents the Torsen
dual-drive differential, a type of limited slip
differential that relies solely on the action of
gearing instead of a combination of clutches and
gears.
- 30 BC–20 BC: Differential gear
systems possibly used in China
- There are many claims to the invention of the differential gear but it is
possible that it was known, at least in some places, in ancient times.
Some historical milestones of the differential include
- Epicyclic differential
- An epicyclic differential can use epicyclic gearing to split and
apportion torque asymmetrically between the front and rear
axles. Epicyclic gears are also called planetary gears because the
axes of the planet gears revolve around the common axis of the
sun and ring gears that they mesh with and roll between.
- An epicyclic differential can use epicyclic gearing to split and
apportion torque asymmetrically between the front and rear
axles. Epicyclic gears are also called planetary gears because the
axes of the planet gears revolve around the common axis of the
sun and ring gears that they mesh with and roll between.
- Spur-gear differential
- This is another type of differential
that was used in some early
automobiles, more recently the
Oldsmobile Toronado, as well as
other non-automotive applications.
It consists of spur gears only. A
spur-gear differential has two
equal-sized spur gears, one for each
half-shaft, with a space between
them. Instead of the Bevel gear, also
known as a miter gear, assembly (the
"spider") at the centre of the
differential, there is a rotating
carrier on the same axis as the two
shafts.
- This is another type of differential
that was used in some early
automobiles, more recently the
Oldsmobile Toronado, as well as
other non-automotive applications.
It consists of spur gears only. A
spur-gear differential has two
equal-sized spur gears, one for each
half-shaft, with a space between
them. Instead of the Bevel gear, also
known as a miter gear, assembly (the
"spider") at the centre of the
differential, there is a rotating
carrier on the same axis as the two
shafts.
- Non-automotive applications
- The earliest definitely verified use of a differential
was in a clock made by Joseph Williamson in 1720. It
employed a differential to add the Equation of Time
to local mean time, as determined by the clock
mechanism, to produce solar time, which would
have been the same as the reading of a sundial.
- The earliest definitely verified use of a differential
was in a clock made by Joseph Williamson in 1720. It
employed a differential to add the Equation of Time
to local mean time, as determined by the clock
mechanism, to produce solar time, which would
have been the same as the reading of a sundial.
- Application to vehicles
- A vehicle with two drive wheels has the
problem that when it turns a corner the
drive wheels must rotate at different
speeds to maintain traction. The
automotive differential is designed to
drive a pair of wheels while allowing
them to rotate at different speeds. In
vehicles without a differential, such as
karts, both driving wheels are forced to
rotate at the same speed, usually on a
common axle driven by a simple
chain-drive mechanism.
- A vehicle with two drive wheels has the
problem that when it turns a corner the
drive wheels must rotate at different
speeds to maintain traction. The
automotive differential is designed to
drive a pair of wheels while allowing
them to rotate at different speeds. In
vehicles without a differential, such as
karts, both driving wheels are forced to
rotate at the same speed, usually on a
common axle driven by a simple
chain-drive mechanism.
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