I am thinking that this could be what is meant..

http://en.wikipedia.org/wiki/Torsen

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Note added at 20 mins (2012-12-01 07:05:25 GMT)
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The Torsen differential works just like a conventional differential but can lock up if a **torque imbalance** occurs, the maximum ratio of torque imbalance being defined by the Torque Bias Ratio (TBR).[3] When a Torsen has a 3:1 TBR, that means that one side of the differential can handle up to 75% while the other side would have to only handle 25% of applied torque. During acceleration under asymmetric traction conditions, so long as the higher traction side can handle the higher percentage of applied torque, no relative wheelspin will occur. When the traction difference exceeds the TBR, the slower output side of the differential receives the tractive torque of the faster wheel multiplied by the TBR; any extra torque remaining from applied torque contributes to the angular acceleration of the faster output side of the differential.

See below:

Also gives "angular impulse" but I am not aware of this term, and in any case torque shock load fits the term exatly

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Note added at 23 Min. (2012-12-01 07:09:01 GMT)
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Reference:
The permitted overload torque (shock load) is defined as a short- term increase in output torque, e.g. during the start-up of a motor. In these all-metal PLGs, the ...
motion.schneider-electric.com

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Note added at 28 Min. (2012-12-01 07:13:34 GMT)
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FYI. Definition of angular impulse (seems more to do with maths):

From Wikipedia, the free encyclopedia
Common symbol(s): I, J
SI unit: N · s = kg · m/s
Classical mechanics
History of classical mechanics
Timeline of classical mechanics
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v t e
In classical mechanics, impulse (abbreviated I or J) is defined as the integral of a force with respect to time. When a force is applied to a rigid body it changes the momentum of that body. If the momentum of an object changes, then either the mass or the velocity or both change. If the mass remains unchanged, as is most often the case, then the velocity changes and acceleration occurs. A force produces an acceleration, and the greater the force acting on an object, the greater its change in velocity and, hence, the greater its change in momentum. However, changing momentum is also related to how long a time the force acts. If a brief force is applied to a stalled automobile, a change in its momentum is produced. The same force applied over an extended period of time produces a greater change in the automobile's momentum. The quantity of impulse is force × time interval, or in shorthand notation:

peak values.