Quote:
Originally Posted by venture
I just read some gear talk and I read that helical gears are quieter than straight gears in transmissions, so part of my theory could be wrong.
I can find quotes of people saying both. My thoughts in my previous post (more contact area) are why I believed the louder theory. I don't know what to think now?? ENGINEERS? PHYSICISTS?!? PLEASE WEIGH IN!
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The idea behind helical gears being quieter is due to the constant contact between the gear teeth. With helical gears, the broader contact area means that there is always a pair of teeth engaged as the gears rotate - ie, contact begins on the next set of teeth BEFORE the current set disengages. This gives a smooth and quiet transition between the teeth as the torque is gradually loaded and offloaded on each tooth pair.
With straight cut gears, as smooth as they can be made to be, there must be a clearance (and consequently, backlash) between the gear teeth to prevent the teeth from binding. This means that there is a small gap between when the current teeth are engaged and when the next set are engaged, and only one set of teeth are ever engaged at any one time. This causes extra noise and shock as the point of contact abruptly transitions from one tooth pair to the next.