Backlash in planetary gear trains 2

[lathanag]

Can someone tell me how backlash could be specified in a Planetary gear train( Planet and sun and between planet and annulus). All the gears are corrected to give high load carrying capacity. Is it true that a S corrected gear works with zero backlash .

 

[diamondjim]

Because of inaccuracies in the production of gears,
all need some backlash to avoid jamming the parts.
Also because of heat buildup in the system, backlash
is still required. I do not understand your S
correction part of this.

 

[lathanag]

S correction refers to the technique of profile modification of gears to give some desirable characteristic to the gear such as higher load carrying or higher contact ratio. In an S corrected gear the profile shift given to the cutter is not equal for pinion and gear. In the case of an So corrected gear sum of correction factors for the pair is equal to zero.ie x1 = -x2. I hope this explains your query.

 

[diamondjim]

Lathanag,
Sorry to have overlooked this post.
Planetary Gears can be modified beyond what you
described. Profile shifts can be additive and
have new center distances. They do not have to
sum to zero unless you cannot change your center
distances. I have designed the sun at 50 percent
long, planetaries at 25 percent, and internal
gear at zero or with a profile shift. It is
cumbersome design wise. I often use an external
gear program to design the first two, and then an
internal gear program to desing the final.
Have also used 66 percent, 33 percent, and internal
gear with 33 percent change. Even if you have fixed
centers, often by varying these percentages, and using
different number of teeth, you can arrive at a suitable
design. Your first comment is what I mostly see in
designs. I do not know if the first and last must be
a direct ratio or an integer value. How do you use
these planetary designs. I agree that there is very
little info about these.


I have seen mostly.