Hello,
This is my first post on this site, and I am in no way an expert in gear design. However, we have been having a discussion at work about the difference between crossed-axis helical gears and worm gears. A co-worker posted the question as to why one is much more efficient than the other. However, I argued that crossed-axis helical gears only truly differ in that they may have an involute profile, with the difference in efficiency being because of the reduced gear ratio, increased lead angle, and higher number of teeth. Am I correct in believing this?
Additionally, we know that worm gears are generally the most quiet gears for speed reduction. However, would a gearbox be that much noisier if crossed-axis helical gears were used instead? The application in question has an input speed of around 1800RPM with an input torque of around 0.30N*m. We want to achieve a reduction of around 300 using crossed-helical gears, followed by a worm gear and finally a planetary set. The other alternative is to use two worms. However, we want to maintain a higher efficiency.
Additionally, we have been using MITCalc for our calculations. However, when using these low-power worm gears, MITCalc outputs a 50% efficiency on a worm gear that has a meshing efficiency of 92%. The major losses are attributed to "no-load losses" which are separate to bearing and sealing losses in this case. My belief is that these losses are a rule of thumb approximation to oil churning losses which we would not experience because our gears would only be greased. However, my co-workers disagree. I argue that if these worm gears were properly manufactured, mounted and aligned, they would come close to the 92% meshing efficiency and would most certainly have a higher efficiency than 50%. Is this too hopeful?
Thanks again for any info that you can give me. Again, I apologise for my lack of expertise and for the long-winded message.
Thanks and best regards,
-L[tt][/tt]
This is my first post on this site, and I am in no way an expert in gear design. However, we have been having a discussion at work about the difference between crossed-axis helical gears and worm gears. A co-worker posted the question as to why one is much more efficient than the other. However, I argued that crossed-axis helical gears only truly differ in that they may have an involute profile, with the difference in efficiency being because of the reduced gear ratio, increased lead angle, and higher number of teeth. Am I correct in believing this?
Additionally, we know that worm gears are generally the most quiet gears for speed reduction. However, would a gearbox be that much noisier if crossed-axis helical gears were used instead? The application in question has an input speed of around 1800RPM with an input torque of around 0.30N*m. We want to achieve a reduction of around 300 using crossed-helical gears, followed by a worm gear and finally a planetary set. The other alternative is to use two worms. However, we want to maintain a higher efficiency.
Additionally, we have been using MITCalc for our calculations. However, when using these low-power worm gears, MITCalc outputs a 50% efficiency on a worm gear that has a meshing efficiency of 92%. The major losses are attributed to "no-load losses" which are separate to bearing and sealing losses in this case. My belief is that these losses are a rule of thumb approximation to oil churning losses which we would not experience because our gears would only be greased. However, my co-workers disagree. I argue that if these worm gears were properly manufactured, mounted and aligned, they would come close to the 92% meshing efficiency and would most certainly have a higher efficiency than 50%. Is this too hopeful?
Thanks again for any info that you can give me. Again, I apologise for my lack of expertise and for the long-winded message.
Thanks and best regards,
-L[tt][/tt]
