Quote:
Originally Posted by T^2
With a dog gear, there's also the constant risk of shearing the screw that transfers torque.
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The screw inside the dog gear does not transfer torque. It only takes shear load shifting. The dog gear transfers torque through its hexagonal hole which couples its rotation (and therefore the engaged gear's) to the hex shaft. If the screw does shear, it can lead to major problems with transmitting torque, but this is because the dog is now free to ride axially along the shaft such that it may not engage with the gears anymore.
This being said, the shearing of a screw is not a flaw with the dog gear design if you don't want it to be. A roll pin can be used for this application and is much stronger in shear than the bolt, but it is more difficult to assemble and disassemble.