Worn Shifting Dogs

[IrisLab]

Can some describe a "dog" system? Or point to a good white paper? Unforntunately, "dog" is a very common word and google is more than happy to rain my search with cats and dogs!

Any engineering drawings available? Sketches? More importantly, equations!

[RogerR]

the technokat white paper is http://www.technokats.org/documents/shiftonfly.pdf

for the 2003 two motor design

[Matt Reiland]

Last year we were using the Generation 1 Technocats shifter that had the separate dogs mates attached to the gears. In practice we had assembled the transmission too narrow and while at full speed it shifter and ended up in high and low immediately locking up the transmission and shearing off the three screws that held the dog mate onto the gear. We took it apart and welded the gear to the dog mate and it worked for a while longer until it was assembled yet again narrow. This time, under a full power shift it again locked up the transmission but the shock went through it and sheared off the motor pinion on the bosch. We put a new motor in and used it the entire season and post season with no signs of wear on the dog or dog mates. With generation 2 having the dog mate milled into the steel gear it looks to be even stronger. My 'non- expert' opinion is that it is oversized for the loads that are being applied to it by our motors in the kit and for its limited use in a FIRST season it works spectacularly.

[FotoPlasma]

Originally Posted by IrisLab

Can some describe a "dog" system? Or point to a good white paper? Unforntunately, "dog" is a very common word and google is more than happy to rain my search with cats and dogs!

Any engineering drawings available? Sketches? More importantly, equations!

Along with the whitepapers from the Technokats' 2002 and 2003 transmissions, here's a picture of team 716's implementation of this type of "dog" shifting mechanism:
http://www.chiefdelphi.com/forums/pi...&quiet=Verbose

[Stu Bloom]

Originally Posted by IrisLab

... Any engineering drawings available? Sketches? More importantly, equations!

Dave,

The TechnoKats/Andy Baker white paper (referenced above) is probably the best thing you will find to help explain this. If you still need any help with visualization please email me. I can try to put together some additional 3-d CAD views and/or animation of how this shifting arrangement works.

Good Luck!

[Andy Brockway]

We have not seen any wear after the three off-season competitions we ran with the square dogs. In fact the shifting seemed to get easier the more we ran the gearboxes. The square 'dog' is a nominal size, ie 1.25" square, while its mating hole is .004" larger, ie 1.254" square. This gives the needed clearance for the dog to fall into the hole. The corners do not mesh exactly, mostly clearance; the force is applied at a point similiar to a box wrench on a nut.

BTW we do not have any speed matching when we shift. The drivers pull a trigger to shift up and let go to shift down. Shifting down while running at high speed is not good for the gearbox just as it is not good for your father's car