Quote:
Originally Posted by asid61
From my understanding worm gears are not all that inefficient if used in certain ways. Judging by what it says on this site: http://www.roymech.co.uk/Useful_Tabl...orm_Gears.html
you can achieve a decent efficiency of 70% or higher using a bronze wormwheel and 2-lead steel worm if they are turning ok, and should not backdrive either.
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Let me say this about that.
First 70% is crazy high for worm gears in the real world, especially worm gears that a FIRST team can afford (both in terms of weight and $). It is really hard to get worm drives that are this efficient. You have to manage the coefficient of friction between the worm gear and the worm wheel. You have to manage the lead angle. You have to worry about the thrust loads (and manage them efficiently). You have to get the tooth forms just so... The list goes on and on. Getting over 50% is crazy good and probably not even possible for most FIRST designs because teams are almost always using worm drives to get high ratios in one gear stage which is at odds with high efficiency.
Second, if you do everything right and you get anywhere close to 50% efficient, that gearbox is going to be easily back driveable. Believe me. This is the case.
There is another CD thread about pins on window motors. The REASON that Denso puts those pins in their window motor is because they have made their worm drive efficient enough that it will no longer keep the window from dropping on a bumpy road.
Dr. Joe J.