WEBVTT

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Torsen is a trademark of 
the JTEKT Corporation.

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The Torsen differential has 
many patented components

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and is the most unique and ingenious
method of providing differential action

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while overcoming the traction
difference problem.

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The internal components of 
a Torsen are quite different

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from that of a conventional differential.

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At the heart of the system lies 
a specially shaped gear pair assembly.

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Let's see the cross-sectional shape 
of these gears at the mating point.

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As can be seen one gear is a spur gear

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and the other one is a worm gear.

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A Torsen works on the simple principle
of worm gear worm wheel.

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That is, a spinning worm gear 
can rotate the wheel.

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But the rotating wheel cannot 
spin the worm gear.

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Throughout this discussion just 
keep this principle in mind.

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A pair of such worm wheels 
are fitted with the case.

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So the engine power received by the case
is transferred to the worm wheels.

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Each end of the wheels 
is fitted with a spur gear.

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Now let's consider different 
driving scenarios.

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When the vehicle moves straight,

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the worm wheels will push 
and turn the worm gears.

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So both the drive wheels 
will rotate at the same speed.

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Please note here that, in this condition,

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the worm wheels do not spin on its own axis.

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In this condition the whole mechanism 
moves as a single solid unit.

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When the vehicle is negotiating a right turn

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the left wheel needs to rotate at 
a higher speed than the right wheel.

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This speed differential is perfectly 
supported in the Torsen.

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The worm gear of the faster left axle

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will make the corresponding 
worm wheel spin on its own axis.

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On the other side, relative to the case,

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the slow right axle is turning 
in the opposite direction.

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Thus the right worm wheel will 
spin in the opposite direction.

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The meshing spur gears at 
the ends of the worm wheel

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will make sure that the worm wheels
are spinning at the same speed.

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Thus it guarantees a perfect 
differential action.

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Now let's try to understand how

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the Torsen overcomes the drive 
wheel traction difference problem.

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As you might be aware,

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when your vehicle encounters 
a situation as shown,

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the slippery wheel starts 
to spin very rapidly

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and will draw the majority 
of the engine's power.

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As a result the vehicle will get stuck.

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But, if a Torsen differential 
is used in this case,

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as soon as the slippery wheel 
starts to spin excessively,

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the speed change will be transferred
to the worm wheel.

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The right worm wheel transfers 
the speed change to the left worm wheel

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since they are connected through spur gears.

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Here comes the tricky part.

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The left side worm wheel will not be able 
to turn the corresponding worm gear

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because, as we said, a worm wheel
cannot drive a worm gear.

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As a result the whole mechanism gets locked

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and the left and right wheels turn together.

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This allows a large amount of torque to 
be transferred to the high traction wheel

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and the vehicle can thereby overcome
the traction difference problem.

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To carry the load, two more 
worm wheel pairs are added.

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If you are familiar with the other
common technologies

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used to overcome the traction 
difference problem,

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you might have noticed a great
advantage of the Torsen.

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While the other technologies
allow the drive wheel

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to slip for a limited amount of 
time before it gets locked,

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in Torsen, the locking action 
is instantaneous.

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That means, as soon as the vehicle 
encounters a traction difference track,

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the wheels will get locked.

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To know more about
the clutch pack LSD technology,

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please check the next video.

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Thank you!