[Andy Brockway]

There are several methods currently in use for dog shifters. The basic design uses a component rotationally fixed to the output shaft and allowed to move axially to engage a free spinning gear or gears. Several methods have been used to limit the rotational elements, hex rod in a hexagonal hole and a fixed keyed shaft fitted to an oversized keyway of the dog are most predominant. The engagement of the dog to the gear causes the gear to be fixed rotationally to the output shaft. The power from the motors is fed thru the gears and the shifter is used to select the proper gear ratio during operation.

Most manual transmissions use this method. Motorcycles are a prime example and also incorporate the dog into gears in order to save space and weight. The TechnoKats (45) dogs are design along these lines with three lobes fitting into three pockets. The Who'sCTEKS (716) uses a square dog fitting into a square hole. The TechnoKats use a rod thru the center of the output shaft with a pin at right angle to slide the dog back and forth. The Who'sCTEKS use an outside yoke to do this. Team Epsilon Delta (116) also uses the outside yoke for moving their sliding gear type shifter. In both cases lube between the shaft and dog is sufficient as the total movement is low.

Take a look thru the white papers for all these designs. The Who'sCTEKS 'Dual Speed Shifter' paper has drawings of the keyed shaft method using the square dog. A paper of the 2004 complete gearbox will be posted this summer.

(Tom, Team 195, I can clean up your files and post for you, PM me to discuss)