Transmission problems

[BA BUSA]

page

 

[mike1180]

three shift forks in a trans.

what are you calling "dogs".

The transmission gears lock together with a series of "dogs' or "dogs and slots" The photo below (yellow arrow) shows several of the dogs engaged together so that both gears turn together. Under hard use, the gears can began to separate until the dogs become disengaged, this causes the transmission to jump out of gear.
Now notice in that photo the dogs that are in the circle. They both have angles cut on them where they meet. This causes them to lock together. They cannot separate without first backing up to unload the angles. This is what is done when a transmission has the procedure of an "undercut". The dogs are machined so as to fit together and not be able to "jump" out of gear.

 

[APE Dustin]

There you go. That is the process of undercutting and how it works. Here is a picture of a gear that is worn and needs to be hardwelded back up the original spec. You can see in the pic that the dogs have rounded and are not square cut anymore and since because they became rounded it slipped out of gear and ground against the engagement dog on the gear. This gear is one that was really hammered, normally they aren't as bad as this one.