Strange Gear Noise Problem

[MrAl]

Hello there,


Thanks for reading this post. This is one of the strangest problems i've ever seen.

It all started about a month or two ago when a friend and i went on the net and bought two crank lights. Crank lights are LED flashlights that light up when you turn the crank handle, and they have a battery inside to store the charge for a while so the light stays lit when you stop turning the handle, for say 15 minutes or so. They have a generator that turns via a gear train when you turn the handle. There are five gears inside.

What happened is we got these things for a very good price, but the LEDs in them were not very bright so we decided to change them out for some newer modern LEDs with more brightness.

I ordered the LEDs and eventually changed the LEDs in my crank light first. During the disassembly i accidentally opened the gear compartment and one of the gears fell out. I put it back in after figuring out how it went back in (some of the others came loose also) and it appeared to work fine once reassembled.

What was strange though is that a new pseudo problem had developed. The flashlight now makes a different noise when cranked clockwise than when cranked counter clockwise. The clockwise noise sounds like a gear is hitting something, but the counter clockwise noise sounds smooth as it did before the modification.

Now i thought that maybe something dropped out of the light and got lost, like a shaft spacer, or maybe something else. I didnt worry about it too much as i figured it would eventually wear in once it was used for a long time. But a funny thing happened next. I went to repair the friends light and made sure not to open the case incorrectly after the screws were removed so nothing dropped out. I was extremely careful about this. After i installed the new LEDs i realized that perhaps i could inspect the gear train in this new light and see what part went missing or was installed differently.
What i did was removed one gear very carefully and then the next, then another, three total. Nothing dropped out and nothing was different than my light, so i put it back together.

Astonishingly, now this second light makes the same noise the same way as the first one did ! Only clockwise and not counter clockwise ! As i said, this is the strangest thing i've ever seen.

A guess to what is causing the noise is maybe a gear is cocking slightly when it is cranked in either direction, but when cranked in one particular direction the slight unlevel rotation causes one part of the gear to gently rub against the side of the body. Why this suddenly starts to happen however is really a mystery.

Any ideas at all?


I almost forgot to mention that the first time i took the light apart was when this first started to happen, even before anything was changed inside the light.

THANKS!

 

[Dean Huster]

Things like that always sound different when operated in reverse anyway ... your typical cordless drill is good example of that. If it bothers you that much, pull it apart again (don't play "52 pickup" this time) and reverse one of the gears on the shaft and reassemble and see if that helps. While it's apart, see if there's some marks on the inside of the case where a gear is rubbing. Are these all-plastic gears? Are they lubricated in any way? How much wear was on them before you originally took the case apart? It may be that if you carefully look at cog wear, you might be able to put the gears back in as they were originally assembled. Those are straight-cut gears rather than helical-cut, aren't they?

 

[canadaelk]

Well Al, with any luck one of you is left-handed....E

 

[Joe G]

when you take the light apart again to reverse the gear, check the gears to see if the is a timing mark like a dimple of sorts, some gears have a referance mark on both
mating gears, i really doubt it though, but hey, it can't hurt to look. if they do, match the marks on the corresponding gears.

 

[Mickster]

I have one of those types of light packed away in my night-fishing kit.
From memory and mine has never been opened, it does exactly the same when turned in one direction and then the other.
However, this one has a red LED to indicate charging. The LED only illuminates when cranking in one direction and not the other.
Perhaps the direction which has the loudest geartrain noise is the correct direction for charging, due to load upon the motor?

Does yours have an LED to indicate charging?

 

[MrAl]

Hi guys,

The gears can only go in one way because they have two gears on each gear and they couldnt install any other way.

This light charges in either direction as it uses a bridge rectifier inside to makes sure the battery charges correctly.