Speed increase in Geared Drive Train

I work for a fishing reel manufacturing company. We are developing a new prototype reel and need to develop a geared drive train that produces a 16:1 ratio (16X increase in speed) between a manual crank handle and the output pinion shaft. We are having difficulty designing this increase in speed with anything less than a two-stage or three-stage transmission.

I know that a planetary gear arrangement is often used to generate a gear reduction in shaft speed, but I was wondering if anyone knew if such an arrangement is a viable alternative to gain an increase in speed so that one revolution of the crank handle could produce up to 16 revolutions of a pinion shaft.

Any suggestions would be most appreciated.

Thank you in advance for any guidance any of you might provide!

 

[plasgears]

Consider a crossed helical drive similar to a worm drive. Drive the worm with a double start, which is engaged with a gear with 32 teeth. It should back drive nicely. Another way is to have a triple start worm driving a 48 tooth gear.

Use the design approach for worm gears. Remember that the worm lead angle is calculated first, and the gear helix angle equals this worm lead angle.

 

[EnglishMuffin]

Planetary gearboxes are certainly used for speed-up drives - in wind turbines for example. The main advantages of a planetary are weight and compactness, both of which would seem desirable in your application. You would pribably need two stages to get 16:1.

 

[GearmanPE]

Planetaries shine when trying to increase power density. My guess is that isn't your design objective.

Consider helical gears with very few pinion teeth. For example, say the pinion had only 3 or 4 teeth, then the gear has 48 teeth. At 20 DP, the gear is only 2.5 inches.

The pinion needs to be of a high pressure angle with the tooth tips pointed. The profile contact ratio may fall below 1, so you need helical teeth to provide continous transmission of motion. This is a specialized area of gear design.

 

[EnglishMuffin]

To get down to 3 or 4 teeth you would probably need to use something other than an involute profile - maybe a Concurve - but even that may not be able to go to so few teeth.

 

[strokersix]

CraigBarker,

You may wish to contact

http://www.kleissgears.com

or

http://www.akgears.com

for assistance with custom gear design, especially plastic gears.

I've worked with but I'm not affiliated with either Kleiss or AKGears in any way.

Mike

 

[MattRR]

There was an AGMA paper published by Bernie Berlinger? about achieving high ratios with few pinon teeth. Evoloid?