Andy Mark Planetary + side load

[Salik Syed]

for our shooter rollers we are using FPs mated with Andymark planetarys, there will be a sprocket straight on the shaft... how well will they tolerate this side load, there is not very much torque ... the rolelrs will be spinning near free speed (except whena ball goes through)

[sanddrag]

DO NOT SIDE LOAD THAT GEARBOX!!!! At all. Period. That gearbox is not built for any sort of side load whatsoever. Have an independent shaft for your mechanism and then link the two with a flex coupling of some sort.

Just yesterday, our AM planetary from last year got all bound up. It wouldn't even turn. We opened it up, cleaned it all out, and found there was a planet siezed on its pin. We pressed the pin out of the planet, reamed out the planet just a little, and reinstalled. We packed the gearbox full of white lithium grease and now it runs pretty good actually.

Couple of tips:
Run it in for a long time. A really long time. It's a bit crunchy when new.
Then, clean it out with engine bright or similar degreaser (avoid the bearings)
Then, pack it full of white lithium grease. (I mean lots, no empty space, all grease).
Also, make sure you use loctite on all the screws, especially the FP mounting screws.
Make sure you torque the backplate screws in a careful fashion (don't crank all the way down on one, then go to the next one). Torque them just a little bit at a time. Spin the output shaft by hand to make sure it still turns easily. If not, loosen the bolt you just tightened and try again, or try tightening a different backplate bolt.

At first, it is a bit tricky to get these things running smooth, but after a while, they'll wear in and be a bit better.

In any case, don't load that gearbox in any fashion other than axial torque. (that means no side loads and no thrust loads).

[Mike Norton]

I know we tried to run two tyco motor using Andy Mark Planetary. and put them into the gear box which they where made for. We found out already it is not a good thing.


You might want to rethink what motors you use. we found out if you want to shoot quickly, you can not have the motor slow down at all when you shoot out a ball. if so the next ball will be off target. We solved our problem by picking better motors suited for the shooter.

[Salik Syed]

hmmm... well thats a bit disheartening... i think we will have to re-work our design then ... maybe add some support bearings on the other side?

[Dick Linn]

Sanddrag,

Perhaps you could be just a bit more clear for the new folks here when you say "In any case, don't load that gearbox in any fashion other than axial torque. (that means no side loads and no thrust loads)".

[sanddrag]

Don't put shaft on it, don't put a wheel on it, don't put a sprocket on it, don't put a pulley on it. It is made to have only a small gear on it, nothing else.

[Dick Linn]

In other words, it is only meant to drive a second stage gear stage that is fully supported against any and all side loads and end loads, and the motor only has to support the load against it's output gear. Well said in the vernacular, just thought some might not appreciate it.

I think many expect a lot more of a little motor than they can give. Hey, we get power. But don't expect the motor to make up for everything downstream.

[Alekat]

Would the regular CIM motors handle sideloads any better?

[Cory]

Would the regular CIM motors handle sideloads any better?

The small ones?

Not really. I sure wouldn't put a sprocket on it's output shaft and drive my wheels from there. You can probably get away with some side load, but your robot will thank you if you eliminate as much of the load as possible.

[Andy A.]

Side loads on most motors won't kill them outright, but it sure isn't healthy for them.

The rotor of a motor is supported at two places, one at each end of the motor can, usually with bushings. By placing a side load directly on a motor you drastically increase the amount of friction between the shaft and bushings with a corresponding drastic decrease in power output. Really heavy loading might wear the bushings enough to pull the rotor out of alignment in the can, upsetting the magnetic fields. The motor could probably handle that kind of abuse for a season, but you would be putting an enormous strain on it and loosing a lot of power in the process.

As for the AM planetary, I think it's clear that it's not a good idea to use it with anything more then a small spur gear. And even then, you should be very careful that that gear has a nice clean mesh with what ever it drives. If you really wanted, you could support the end of the output shaft and eliminate that load, but it might be more trouble that it's worth. As always, the final say is with Andy or Mark, but they'd probably tell you the same thing.

As a side note, the globe motor and it's planetary gear set die quickly when side loaded. Always be careful of cantilevered shafts! They spell doom for FIRST teams.

-Andy A.

[Alekat]

The small ones?

Not really. I sure wouldn't put a sprocket on it's output shaft and drive my wheels from there. You can probably get away with some side load, but your robot will thank you if you eliminate as much of the load as possible.

Remember, we're not talking about our drive wheels, but our shooter wheels. And besides, i'd rather leave the manners up to the drivers ;)