The document discusses the torque converter and its role in automatic transmissions. It explains that the torque converter uses transmission fluid to transfer power from the engine to the transmission hydrodynamically. The torque converter contains an impeller connected to the engine, a turbine connected to the transmission input shaft, and a stator that redirects the fluid flow to multiply torque. The automatic transmission also contains a planetary gearset and hydraulic controls to shift gears without a clutch pedal.

1. TORQUE CONVERTER
&
AUTOMATIC TRANSMISSION
Prepared & Presented By:
Nitin Kukreja

2. RELATION BETWEEN
TC & AT
• Most of the modern vehicles are equipped with internal combustion
engines (ICE).
• On a vehicle with manual transmission (MT), the engine engagement &
disengagement can be done in two ways:
• By pressing the clutch pedal
• By selecting Neutral with the gear-shift lever
• On a vehicle with automatic transmission (AT), the engine
disengagement from the transmission is done automatically, without the
intervention of the driver.
• This is possible thanks to the torque converter‘s work principle.

3. AUTOMATIC TRANSMISSION

4. PLACEMENT OF TORQUE CONVERTER
• The torque converter is placed between the internal combustion engine and the gearbox.
• An automatic transmission, inside its case, contains three main parts: the torque
converter, the epicyclic (planetary) gearbox and the electro-hydraulic control module.
• The ICE crankshaft is mechanically connected to the torque converter. Inside the torque
converter, the engine power is transferred to the gearbox hydrodynamically.

5. WORKING OF TC
• If you have two electric fans, placed on in front
of the other (like in the image on right side),
with one of them powered, what is going to
happen?
• Power is transferred from the left fan to the
right fan through a working fluid (in this case is
air). Obviously, the efficiency of this system is
very low since a lot of air will be dissipated
around the blades of the right fan.

6. TORQUE CONVERTOR
• The same principle applies to the torque
converter, with some differences.
• In the case of the torque converter, both
“fans” are very close together, in order to
minimize the power loss.
• The working fluid is a liquid (AT oil).
• Also, between the two “fans”, there is
another component, which redirects the
fluid flow in order to minimize the losses
and amplifies the transferred torque.

7. TORQUE
CONVERTOR
• There are four components
inside the very strong housing
of the torque converter:
• 1. Pump
• 2. Turbine
• 3. Stator
• 4. Transmission fluid

8. TORQUE
CONVERTOR
• The “fan” which is generating
power is called impeller and it’s
connected mechanically to the
engine crankshaft.
• The “fan” receiving the hydraulic
power is called turbine and it’s
connected mechanically to the
input shaft of the gearbox.
• Between the impeller and the
turbine is a stator, which redirects
the oil flow. The volume created
by these components is filled with
oil.

10. CONSTRUCTION OF
TORQUE CONVERTOR
• The housing of the torque converter
is bolted to the flywheel of the engine,
so it turns at whatever speed the
engine is running at.
• The fins that make up the pump of
the torque converter are attached to
the housing, so they also turn at the
same speed as the engine.
• The pump inside a torque converter is
a type of centrifugal pump. As it spins,
fluid is flung to the outside. As fluid is
flung to the outside, a vacuum is
created that draws more fluid in at
the center.

11. WORKING OF TORQUE
CONVERTOR
• The fluid then enters the blades of the
turbine, which is connected to the
transmission.
• The turbine causes the transmission to spin,
which basically moves your car. The blades
of the turbine are curved. This means that
the fluid, which enters the turbine from the
outside, has to change direction before it
exits the center of the turbine. It is this
directional change that causes the turbine
to spin.
• The fluid exits the turbine at the center,
moving in a different direction than when it
entered. If you look at the arrows in the
figure, you can see that the fluid exits the
turbine moving opposite the direction that
the pump (and engine) are turning. If the
fluid were allowed to hit the pump, it would
slow the engine down, wasting power. This

12. WORKING OF
TORQUE
CONVERTOR
• The stator has a very aggressive
blade design that almost
completely reverses the direction of
the fluid.
• A one-way clutch (inside the
stator) connects the stator to a
fixed shaft in the transmission (the
direction that the clutch allows the
stator to spin)
• Because of this arrangement,
you can understand the, Stator can
spin only in the opposite direction,
forcing the fluid to change direction
as it hits the stator blades.

13. KEY CHARACTERISTICS
• The key characteristic of a torque converter is its
ability to multiply torque when the output rotational
speed is so low.
• This is a feature beyond that of the simple fluid
coupling, which can match rotational speed but does
not multiply torque, thus reduces power.

15. AUTOMATIC TRANSMISSION
• A hydraulic automatic transmission consists of the following parts:
• Torque Converter which is a type of fluid coupling hydraulically
connecting the engine to the transmission.
• A planetary gearset.
• A set of bands to lock parts of a gearset.
• A set of three wet-plate clutches to lock other parts of the gearset.
• An incredibly odd hydraulic system that controls the clutches and bands.
• A large gear pump to move transmission fluid around.