Dog engagement gearbox

[AlfaNeely@xxxxxxx]

In a message dated 5/1/2003 5:59:06 PM Central Daylight Time, 
owner-alfa-digest@domain.elided writes:

> Date: Thu, 1 May 2003 14:31:53 -0400 (EDT)
> From: "." <maxid@domain.elided>
> Subject: Dog engagement gearbox
> 
> What does "dog" mean in "dog engagement gearbox" and "dog clutch"? Sites 
> that offer racing gearboxes use these terms as if they are household words 
> with no explanation offered. What are some advantages/disadvantages of a 
> dog engagement gearbox?
> Cheers,
> Sonny '91 164 S, Baltimore
> maxid @ mind spring -dot- com
> 

       One of Webster's definitions for "dog" is "Any of various devices for 
holding, gripping or fastening something, as one consisting of a spike or bar 
of metal with a ring, hook, claw or lug at the end."
       Hold your hands out with fingers spread and your finger tips pointed 
toward each other.  Now move your hands together such that your fingers slip 
between the fingers of the other hand.  Now try to rotate one hand within the 
other.  That is the concept of "Dog ring engagement."  The fingers or dogs of 
one hand are engaged with the fingers or dogs of the other hand - they are 
hooked together.
       When you shift a 105 / 115 transmission into gear, the slider first 
contacts the synchronizer, which hopefully brings everything to matching 
speeds.  Then the teeth (or dogs) of the slider slip between the teeth or 
dogs of the dog ring.  The dogs guide the teeth of the gears into engagement. 
 When you hear "gears" grinding in an Alfa you are really hearing the dogs 
grinding together.  I guess if the dog rings were completely ground away, you 
might hear the gears grind.
       A true racing transmission may not have synchronizers at all.  The 
transmission may be equipped with very strong dog rings that are simply 
jammed together.  And on many early transmissions there were no dogs to help 
with gear alignment, the gears themselves were simply put together - with 
various degrees of success and grinding depending on the expertise of the 
driver.  I watched a friend assemble a 1915 White Fire Truck transmission - 
there was nary a syncro or dog ring present.


Ciao,
Russ Neely
Oklahoma City
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