High torque planetary gear with low ratio
High torque planetary gear with low ratio
(OP)
Hi, im designing a motor which needs a planetary gear with low ratio, 1:2 is ideal, but due to the principle of ( ratio ) = (sun teeth + ring teeth)/(sun teeth) thats not possible.
The motor has an output torque of 85Nm and max speed of 4000 rpm. I havent found any solutions or manufacturers who delivers this kind of gearhead with lower ratio than 1:4.
Any tips?
The motor has an output torque of 85Nm and max speed of 4000 rpm. I havent found any solutions or manufacturers who delivers this kind of gearhead with lower ratio than 1:4.
Any tips?





RE: High torque planetary gear with low ratio
Why does the gearbox have to be planetary?
A 2:1 ratio can be easily done with one set of gears. The only downside is that the output shaft does not line up with the motor shaft.
--
JHG
RE: High torque planetary gear with low ratio
RE: High torque planetary gear with low ratio
I bet you are looking for a purchased solution. But A bunch of US automatic transmissions have ratios in the ballpark.
http://www.oldengine.org/unfaq/leadfoot/trans.htm
Some aftermarket companies supply ratios real close to 2:1.
http://www.tciauto.com/tc/gear-ratios/
Adapting those gear sets would be quite an engineering exercise.
RE: High torque planetary gear with low ratio
Well, it doesnt need to be planetary, but it will ease the design and manufacturing process if the output shaft is coaxial to the motor shaft.
Also, in my head, a planetary gearbox is more compact due to multiple gears transferring the torque. I would also prefer to have a off the shelf solution that I could add between the motor and the outputshaft.
I will however evaluate using standard gears.
Do you have any tips on suppliers who deliver gears and have a easy to use CAD-file database? Metric is preferred :)
http://khkgears.net/ seems promising, but other tips are welcome.
RE: High torque planetary gear with low ratio
Modelling gears in CAD is easy, especially of you have some old drafting books around. My 1941 copy of French's Engineering Drawing comes in handy. This assumes that you are not not using the CAD model to manufacture your gears.
Off the shelf gears need to modified to attach to your shafts. This is especially true for high torque applications. Forget those set screws! If you get a gear cutter to fabricate your gears, they can cut the bore first, and use it to fixture the tooth cutting. I don't know how COTS gears are bored out.
--
JHG
RE: High torque planetary gear with low ratio