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Re: Quattro Digest V2 #521

> From: Steve Evans <sevans@radstone.co.uk>
> Date: Wed, 25 Oct 95 10:38:13 BST
> Subject: Torsen Diff. operation
> I am rather curious to know how a Torsen diff. works. I know that it is free
> under braking, yet distributes power between front and rear within certain
> ratios (75%/25% being the maximum difference I believe) when under load.
> How on earth does this box of cogs work? Can anybody out there explain it?

Think about spiral gear drives, which are self locking if you want to
drive them from the ring gear (depending on the angle of the screw and
the coefficient of friction). The torsen diff uses a pair of spiral gears.
Imagine a conventional differential with bevel gears. In the torsen the side
gears are ring gears, the pinion or planetary gears are the spirals. Each side
gear has it own spiral gear. The two spiral gears are connected to each other
with spur gears and their shaft is carried by the differential ring gear
(crown gear). The spiral gear drives work close to their locking range when
both wheels transfer toque to them. If one side looses load the spiral gear
drive on that side locks and that locks the other side as well because the
spiral gears are connected together with the spur gears.
It sounds confusing, but it becomes clear if you look at a digram of it.

Peter Orban
National Research Council of Canada
Internet: peter.orban@nrc.ca