pic: 2451 PWNAGE Planetary Drive

[Mr V]

Originally Posted by JohnFogarty

Besides weight saving and real-estate gain. Are planetary gearboxes more or less efficient than regular non-planetary gearboxes?

Originally Posted by pwnageNick

Generally they are less efficient. Due to this being a custom setup, to know what the efficiency of this setup would be a prototype would need to be built to find that out. A prototype would also test any issues with loads, and how stable the wheel would be.

In general a planetary reduction is less efficient than a spur gear reduction. However this set up isn't really a planetary reduction and should have a frictional loss essentially a simple spur gear reduction.

The extra frictional losses occur in a planetary reduction because of the increased number of gear to gear interfaces.

In your basic spur gear reduction you have 1 gear to gear interface per stage. With a planetary set up you have 6 or 8 gear to gear interfaces as well as the friction of the pins that the planets rotate on.

This set up however does not have a sun nor really any planets, it is just the driven gear turned inside out.