benefits can someone remove this section it makes no sense besides that it's not really a benefit i've never ever seen a situation where a gear was not positively located on the shaft not saying it has never happened but this is not something anyone in real life would consider a benefit someone who is not lazy could also add a section to explain the fact that true herringbones are only useful for pumps for power transmission testing has shown that double helicals with the gap in the middle deflect more evenly across the teeth and wear more evenly they are also important for submarine use quieter