New main gear set

[Matt-L]

A guy at our club recently fitted THIS Align main gear set to his 700 but it seems extremely LOUD

His Heli sounds like a damn Turbine now . Such a loud whining noise.

Was just wondering if any of you guys are using this upgrade and if yours is the same? Maybe he's overlooking something, i.e. bad bearing etc.

[Tim Procter]

Mine was the same Matt, It will get better as it gets used a little..

I must admit I landed mine on the first flight wondering what the noise was.

[jamiem]

Yeah that's normal. Swashbuckler fitted one to his 700LE E, and it sounded awful, changed it to a microheli mod1 main gear and the noise was gone. Very very loud!

[glen_j]

thats a shame its loud, think i'll stick with the original ones for now

[Tim Procter]

thats a shame its loud, think i'll stick with the original ones for now

Glen.

The reason people are upgrading to this gearset is the stock set has been known to strip gears like a candy bar.

I have one of my 700's never ever stripped a main gear.

The other one had 5 main gears strip before I decided it was time to upgrade.

[moyesboy]

Does this mod1 mean the teeth are bigger?
bigger teeth means more error and a larger click as the load goes from tooth to tooth.
The error is biggest in the pinion.
Imagine that the teeth are perfect if they were on a straight rack, rather than a circular gear. The more curved the line of teeth the more error there must be and the more it will click from one tooth to the next.

In theory more smaller teeth should be stronger, except that all the load goes onto one tooth as it meets its mate. Plus the meshing errors (ourt of round gears, less than ideal centre distance) exaggerate the problem. So you actually need bigger teeth to transfer bigger loads. bigger teeth mean fewer teeth on the pinion, and a bigger error from tooth to tooth on the pinion. Hence the noise.

Its better, but a lot more difficult, to design (and to mold) gears with helical teeth. Then the load is shared between a few teeth and they are a lot quieter. Straight helical gears then have a side load - hence the V shaped gear teeth on the mikado like two helical gears back to back so no side load.
Now imagine that gear with the V shaped teeth all round it in a mould - how the can you get it out of the mold? It has to open in a fancy manner and its a pig to make compared to Aligns straigh cut gear mold. That explains some of the the price difference!

Reverse gear is straight cut on most cars - noisy when you go backwards. All the other gears are helicial cut and therefore nice and quiet. Reverse doesn't do many miles so it doesn't matter that they use a cheap gear.



God, I do go on....I wonder if anyone reads my posts sometimes!

[glen_j]

Glen.

The reason people are upgrading to this gearset is the stock set has been known to strip gears like a candy bar.

I have one of my 700's never ever stripped a main gear.

The other one had 5 main gears strip before I decided it was time to upgrade.

yeah i know i've been fortunate so far, will upgrade if i starts stripping till the i'll enjoy the quiet flying (well as quiet as a nitro heli can be )