Today I managed to unscrew the motor off the planetary drive while motoring up to altitude. Not good. Landed missing my canopy, tiny bearings and gears, and some pride. I know it's the less costly system but hey it should work if I do the install correctly. Right now with a new Ammo planetary gear drive I could be flying again but I'm not sure what I did wrong to have the motor screw itself off the back of the gear box. Followed the instructions as best I could. Hope someone with more experience than me(none till now) with planetary drives can offer some advice. The motor is a Ammo 28-56-2300kv turning a 16X10 Aeronaut folder, 60A esc, 3000mah 40c 3s batt. Is this too much torque for the Ammo reduction system to stay together?

Is that the gear box discussed here?

http://www.rcgroups.com/forums/showthread.php?t=1273614

It looks like that has right handed threads on both ends of the black center section of the part that makes up the gear housing. So I guess you attach the motor end to the motor with machine screws, then screw the black housing ring into that, then screw the end with the output shaft on to the end of the black housing, is that about right?

The torque reactions gets a little more complicated with a planetary gearing system.

To get a CW rotation on the prop, I think the motor (sun gear) rotates CCW, and the ring gear/shaft carrier/prop rotate CW. So the torque forces on the motor would have the motor housing and plane wanting to roll to the right.

All of that as seen from a pilot's seat view.

The roll to the right would want to unscrew the right hand threads, wouldn't it?

I realize I only have a 50/50 chance of being right about this...

Maybe a question over on that thread would gt you some help from other first hand users.

Jack

Your experience is very common-I have done it myself, along with many of my flying friends.It usually happens only once!

For the design shown in the link above, the threaded sections at both ends of the gearbox casing must be very firmly fixed to their mating parts. This is best done using a thread locking compound such as Loctite.I use one of the stronger grades which can only be easily removed using heat.I have never had a motor unscrew since using this method.

Thanks painter, Ill try that. Did use threadlocker maybe not enough or grease.got mixed in.

James

On the Great Planes planetary gear drive 24-28mm, are the mounting holes on the front of the gear box that go to the firewall 19mm center to center, or 16mm?.

Thanks! Mitch

It is absolutely crazy that you can't find that kind of info listed on the Tower Hobbies pages and even crazier that the tech support guys won't come up with an answer.

I suppose, like a lot of businesses in this country, they are having trouble finding high school graduates that can read a rule?

If you don't get a reply here you might try a PM to the guy that started this thread or the thread I linked to below, maybe one of them knows or can figure it out for you?

The photos in this thread make it look like it is a square pattern, it is supposed to fit 24-28mm motors, maybe it is 19 x 19?

Jack

I had the same outcome with my first planetary gearbox. An Aveox motor and Maxon gearbox unscrewing in flight. There was no mention of using threadlock on the joint. Couldn't buy just the 3 small gears (that left the plane thru an air hole); an $80 lesson learned.

Matt

19mm

James

Thanks James. I knew it was 19mm but wanted to be sure.

Jack, I actually got annoyed because if I ordered it then it would be in the mail right away. my point to him was if someone is preparing it for shipping than how can someone not pull the item and check it. I tried tech support and the main number and nobody gave me an answer. The tech support idiot kept saying the same thing that it would take 2 - 3 days for an answer and just was not listening to what I was saying. I have not got that pissed off in about 5 years and called him a useless moron and hung up on him. Not my style but he truly frustrated me.

Mitch,

I can understand how you feel, I've been through similar things with Tower Pro and Hobby Zone both.

I guess you noticed that the two halves of the gearbox can be self unscrewing in the most common mounting. I would probably be inclined to put it together and then drill a 2-56 hole for a locking screw. Or two of them if needed. The business about it having to be lubricated and Loctited both is an invitation to disaster. Like Matt says, it invites the use of the high strength stuff and then heat is needed to get it apart, etc., etc.

Jack

War, that kid was more worried about someone telling him to pull his pants back up over his butt...... Future "Occupy" personnel.