[urq] Locking diff actuators - some history of options

[qshipq at aol.com]

The problem is unless locked and unlocked positions are energized all the time, there is no "constant engagement" by definition.  In every locking diff design I've seen (including Audi and Toyota factory lockers), constant engagement is with a 'stop' for the dog clutch fork, in the lock and unlock positions.  The two stop positions are assured by either spring detent pressure (with worm geared motor - toyota) or constant engagement (early audi manual spring detent design, and later vacuum actuator design).  I suppose you could use the spring design found in the pre-84 urqs on the actuator rod to assure 'unlock' hold.  Easy to retrofit that to 84> lockers.  But that would require constant energizing in the lock-on position.

Back when I looked at the solenoid locking option, I saw issues with it's intended design.  Along with the concerns above, all locking actuators should have a spring type cushion to allow a buffer for equal gear speed.  In the vacuum actuator, the diaphram is the buffer, in the toyota worm gear, it has a spring built into the actuator rod.  

Can a solenoid work?  Sure.  Does it potentially have design drawbacks over the vacuum actuator?  Absolutely, as fully unlocked and fully locked dog clutch positions are not assured in a solenoid system.  I'm not sure I really understand the need for solenoids.  A properly functioning vacuum actuator has proven to work for millions/billions of miles in the audi.  You like electric switches?  Use the 'smart box' found in the 91-94 rear diff actuators.  Put a (extra) momentary contact switch for each diff where-ever you want.  Heck, you could even put a ground diff-lock disable circuit (blue white wire) in during braking.  Here's a early shot of the dual electro-pneumatic locker setup I installed in my old 83
http://forums.audiworld.com/album.php?albumid=37342&pictureid=46522

At some point we need to look at that solenoid idea, and wonder why it's not used in production/aftermarket locking diff actuation.  

Scott J
84 urq
83 urq ice track car



 

-----Original Message-----
From: vittorio at mybares.com
To: bob <bob at maxboostracing.com>
Cc: cody at 5000tq.com; larichard at plguide.com; laraa at sympatico.ca; urq at audifans.com; quattro at audifans.com; qshipq at aol.com
Sent: Sat, Feb 13, 2010 7:39 am
Subject: RE: [urq] Locking diff actuators - some history of options


Confirmed - I found a pre-built circuit that allows adjustment of rate and duration of the pulse. So when when the switch is in the on position it pulses to ensure constant engagement.


Then some switches that have momentary-on, and constant on (DPDT) - that allows to hit the momentary to unlock, and constant on to engage the timer circuit to keep it locked.


I like the idea of the buttons on the steering wheel - but that'll be in a later version.


-------- Original Message --------
Subject: Re: [urq] Locking diff actuators - some history of options
From: bob <bob at maxboostracing.com>
Date: Fri, February 12, 2010 3:46 pm
To: qshipq at aol.com
Cc: cody at 5000tq.com, larichard at plguide.com, laraa at sympatico.ca, 
vittorio at mybares.com, urq at audifans.com, quattro at audifans.com

      Thats exactly right... in version 1.0, when you hit the diff lock button the solenoid engaged, but I found that with an adequate flogging they would eventually come undone.  Version 2.0 had a timer circuit in it, that kept pulsing the solenoid a few times a second to keep it engaged, and it worked perfectly.
 Bob