Heavy Mechanic

Torque Converter

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 Objective: To identify the main basics of a torque converter.

Content:
• A Torque Converter
• Functions of Torque Converter
• Parts of a Torque Converter:
a) Impeller or Pump
b) Stator
c) Turbine
• Types of torque converter

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 Did you know that…

Herman Fottinger, a German

engineer, devised and received

a patent in 1905 on a fluid drive

and torque converter.

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 A Torque Converter
A type of fluid coupling which is used
to transfer rotating power from the
engine of a vehicle to the transmission.
It takes place of a mechanical clutch in
an automatic transmission. The main
function of it is to allow the load to be
isolated from the main power source. It
sits in between the engine and the
transmission.

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 Main functions of the torque converter
1. It transfers the power from the
engine to the transmission input shaft.
2. It drives the front pump of the
transmission.
3. It isolates the engine from the load
when the vehicle is stationary.
4. It multiplies the torque of the engine
and transmits it to the transmission. It
almost doubles the output torque.

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 Parts of a Torque Converter

a. Impeller or Pump
It has curved and angled blades,
rotates with engine speed, and is made
up of automatic transmission fluid. It
acts like a centrifugal pump that draws
fluid from the automatic transmission
and delivers it to the turbine. It is
connected to the casing and the casing
is connected to the motor shaft.

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 b. Stator
The stator is located in between the impeller
and the turbine. The main function of the
stator is to give direction to the returning
fluid from the turbine so that the fluid enters
the impeller in the direction of its rotation. It
is mounted with a one-way clutch that
allows rotating it in one direction and
preventing its rotation in other direction.

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 c. Turbine
The turbine is connected to the input
shaft of the automatic transmission.
It is present on the engine side. It
also consists of curved and angled
blades. The blades of the turbine are
designed in such a way that it can
change the direction of the fluid
completely that strikes on its blades.

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 Types of torque converter

1. Single-Stage
They are simple, tough and reliable.
Basically consists of three elements:
• the turbine
• the stator
• the impeller
They come in two housing types:
stationary and rotating.

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 2. Three Stage
They employ three rings of turbine
blades, as well as two sets of reactor
or stator blades. The effect of this
design is increased torque, up to five
times the amount of motor output
torque, when the motor is stopped.
they also come with stationary and
rotating housing.

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 Working principle of torque converter

It has three stages of operations:

1. During stall (stop) condition of

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 2. During acceleration, the turbine
speed keeps on increasing. As the
speed of the turbine increases the
torque multiplication reduces.
3. The coupling point is when the
turbine achieved approximately 90 %
speed of the impeller. The lock-up
clutch comes into play and locks the
turbine to the impeller of the converter.
The lock-up clutch engages only when
the coupling point is achieved.

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 NOTE:
1. The maximum torque multiplication
takes place during stalling condition.
2. The stator remains stationary
before coupling point and helps in the
torque multiplication.
3. The lock-up clutch engages when
the coupling point is achieved and
removes the power losses resulting in
increased efficiency.

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 Quiz
1. ____ devised and received a patent on a fluid drive and torque converter.
a. Isaac Newton b. Leonardo da Vinci c. Nicolaus Copernicus d. Herman Fottinger
2. It acts like a centrifugal pump that draws fluid from the automatic transmission and delivers it to
the turbine.
a. Impeller b. Stall c. Coupling point d. Stator
3. The ____ is when the turbine achieved approximately 90 % speed of the impeller.
a. Impeller b. Stall c. Coupling point d. Stator
4. Herman Fottinger devised and received a patent on a fluid drive and torque converter in ____.
a. 1950 b. 1905 c. 1509 d. 1590
5. ____ happens when the vehicle is stationary and the driver has kept his foot on the brake
paddle to prevent it from moving.
a. Impeller b. Stall condition c. Coupling point d. Stator

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 Quiz
1. ____ devised and received a patent on a fluid drive and torque converter.
a. Isaac Newton b. Leonardo da Vinci c. Nicolaus Copernicus d. Herman Fottinger
2. It acts like a centrifugal pump that draws fluid from the automatic transmission and delivers it to
the turbine.
a. Impeller b. Stall c. Coupling point d. Stator
3. The ____ is when the turbine achieved approximately 90 % speed of the impeller.
a. Impeller b. Stall c. Coupling point d. Stator
4. Herman Fottinger devised and received a patent on a fluid drive and torque converter in ____.
a. 1950 b. 1905 c. 1509 d. 1590
5. ____ happens when the vehicle is stationary and the driver has kept his foot on the brake
paddle to prevent it from moving.
a. Impeller b. Stall condition c. Coupling point d. Stator

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 Conclusions
Cars with automatic transmissions don’t have clutches, so they need a way to
let the engine keep running while the wheels and gears in the transmission
come to a stop. Manual transmission cars use a clutch that disconnects the
engine from the transmission. Automatic transmissions use a torque converter.
When the engine is idling, such as at a stoplight, the amount of torque going
through the torque converter is small but still enough to require some pressure
on the brake pedal to stop the car from creeping. When you release the brake
and step on the gas, the engine speeds up and pumps more fluid into the
torque converter, causing more power (torque) to be transmitted to the wheels.

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