SteveVag

Hi All,

I'm having some trouble with a new GWS EPS 350C motor and gearbox I just got. I installed it in my GWS Pico Tiger Moth to replace the EPS100 I had in there, and I have it driving a GWS 10x4.7 electric prop. I'm using a 7.4V 1200 mAh Lipo. For about 15 to 20 minutes it performed flawlessly and silently, giving me a great increase in power over the EPS100. But then it started making a loud metallic squeaking sound intermittently, and I noticed a drop in power whenever I heard the noise. Any ideas on what the problem might be, and how I might fix it? I've got a heat sink on the motor, and I widened the engine cowling so that it gets a constant stream of air for cooling when it's flying, so I don't think it's overheating, but I could be wrong.

The obvious place to start investigating would be the motor and gearbox bearings, yes? Can they be lubricated with light machine oil, or are they sealed?

Steve Vaglica
Newton MA

Matt Kirsch

My Feedback: (21)

They're just bushings. A small drop of light oil on each bushing might cure the problem, but very little oil will actually get into the bushing area, so be stingy, and don't do it more than once. All you'll do is get oil all over everything, then the dust will stick

One major problem with these motors is that they're unpredictable. Manufacturers make them millions at a time for various applications, not just R/C airplanes. You'll find them in toys, tools, and appliances, both AC and DC. Quality control at the factory isn't the greatest, but that keeps the price incredibly low. You'll find that sometimes these motors last 100 flights, and sometimes they'll last less than one. Normally it's closer to the 100 flight mark, but occasionally, you'll get one that's bad out of the box.

Time Pilot

Matt,

Are you sure?

Taken from a website:

GW/EPS-350C-CS/BB 5.33:1
Compact Electric Power System
Ball Bearing


Also, the replacement bearings. These bearing seem to have balls.

BALL BEARING: for EPS-100C/300C/350C SERIES
[PNBER-1002]

SteveVag

They use replaceable ball bearings on the output shaft of the gearbox, but maybe the motor itself has plain bushings? I'll try to get a small bit of oil into the motor bushings. Thanks for the tip, Matt.

A funny thing about this noise is that I can make it happen on the ground by giving it a little throttle and then quickly cutting the throttle back to zero. Once there's no torque on the prop and it's freewheeling the noise starts up and stays fairly constant unti the prop stops spinning. I can't make the noise happen by just spinning the prop by hand, though.

Does this shed any light on the root of the problem for anyone?

Steve V.

Time Pilot

You're right. Matt and I were talking about different things.

Motor: no bearings.
Gearbox: bearings.

SteveVag

The guys at BalsaProducts where I bought the eps350C say it's probably one of the ball bearings in the gearbox that's bad. So I'm going to try replacing them one at a time to locate the bad one.

Thanks for the input,

Steve V.