Savvas SEIMANIDIS Feb 24, 2013:

interlocking dog clutches - part 2 2. " When a gear ratio requiring involvement of one of the outer selector rods is selected, the selector rod moves one way or the other from the neutral position to engage the dog-clutch outer hub with the dog teeth of selected gear wheel. The movement of the selector rod pushes the contacting interlocking plunger with its spherical ends out of the groove and away from the rod causing the plunger end to contact the straight shank of the rod. The movement of this interlocking plunger at right angles to the selector rod is also relayed to the pin and to the other interlocking plunger, which now is partially located and locked in the groove in the third selector rod. Consequently, while the first rod is free to be shifted to and fro unrestricted, the two selector rods not in use are wedged in the neutral position by the plungers and pin."

- Source : http://what-when-how.com/automobile/gear-interlocking-device...

3. " Planetary gearset with nine speeds, four simple gearsets, six shift elements and two interlocking dog clutches (each use two multidisk clutches and two multidisk brakes). Gearsets are nested to save space."
- http://www.motor.com/newsletters

Savvas SEIMANIDIS Feb 24, 2013:

interlocking dog clutches in autom. transmission The following abstracts explain quite clearly the function of the interlocking dog clutches integrated in the new automatic transmission group of a well known German manufacturer :
- 1. " One of the enablers of the 9HP was the first ever use of interlocking dog clutches in an automatic gearbox. The use of dog clutches save space and enhance efficiency when compared to the use of multi-disc shift elements used in other transmissions. Using four simple gearsets, four dog clutches and two brake bands, the nine forward speeds and reverse can be selected. The gearbox is start/stop capable without requiring an additional fluid pump"
-Source : http://www.bmwblog.com/2012/01/27/the-spun-bearing-zf-9hp-fw...

The main role of this interlocking device is to prevent the simultaneous engagement of two gears. Tony is right : it's the dog gears that are interlocking, i.e. they are not mounted in a parallel assembly but in an interdependent one. The most common type of an interlocking device is the ball and plunger one.

Tony M Feb 24, 2013:

No... ...not AFAIK.

The key point is that earlier automaric gear boxes did NOT use any kind of 'interlocking' clutch, but something much more 'gentle'; I'd be very interested to see just how nowadasy they are able to use something as 'fierce' as a dog-clutch...

But I feel pretty sure that they are saying this is newer technology, compared with the old, non-interlocking kind.

But that's where my knowledge runs out :-(

SwissLocalizer (asker) Feb 24, 2013:

Merci. Justement, il n'est pas fait mention d'autres "clutches" dans le document (plutôt marketing avec quelques termes techniques). Y aurait-il plusieurs embrayages qui s'emboîtent les uns dans les autres ?

Tony M Feb 24, 2013:

Interpretation Indeed, it's a little hard to see just what the 'interlocking' is doing in there: by their nature, 'dogs' 'interlock', so nothing really new there!
The question we need the answer to is probably: Are these 'dog clutches' that are 'interlocking', or 'clutches' that use 'interlocking dogs' — I suspect the latter is possibly the intended meaning, in which case, like you, I can't help feeling that the 'interlocking' is slightly redundant; unless they are trying to make a specific differentiation from other, earlier types of clutches, which were of the non-interlocking leaf type??