Best way to set mesh of main and pinion gear

[lperagallo]

Chris,

What is best when setting up the gear mesh between the main and pinion gear? Is it better to have no backlash but have a rough mesh (not tight, but a notchy feeling when turning the main gear backwards) or have backlash in order to get a smooth mesh. I am trying to get the mesh correct on the turbine because I thought there was too much play between the main and pinion, but when I move everything back to get the backlash out the gears seem to feel notchy. It also looks as though I am moving the turbine to the back most position in the frames. By the way, there has been no crash, just doing maintenance and checking everything out.

What are your suggestions?

Lou

[SeaHawk]

I'd always taken a piece of paper between the clutch pinion and main. You definitly don't want it too tight as you will melt the gear on spool up.

[FBaity]

I have the Bergen Turbine set up a little tight with no back lash. Although I have a bunch of flights on it with no issues it always seemed tight. Wish Chris would chime in here with his thought.

Frank Baity
AMA 38026
Turbine Waiver RW-545, FW-14690
Align 450 SE V-1
MA XL-Pro 2K
Bergen Turbine X 2

[FBaity]

I have the Bergen Turbine set up a little tight with no back lash. Although I have a bunch of flights on it with no issues it always seemed tight. Wish Chris would chime in here with his thought.

Frank Baity
AMA 38026
Turbine Waiver RW-545, FW-14690
Align 450 SE V-1
MA XL-Pro 2K
Bergen Turbine X 2

[FBaity]

Sorry for duplicate post buy needed to install e-mail notificatio option.

Frank

[cbergen]

Sorry guys, between being gone all last week to Ft Benning for the IARC competition and now playing catch up, and HF being down for a period of time, I just got to where I can answer you!!

Simple answer is, you want the mesh as tight as possible, minimal backlash, BUT, BUT it does need to spin smoothly. If you feel a notchiness or roughness when spinning the main gear, find out why.

You also have to check your vertical alignment. The pinion, clutch, clutchbell, triple bearing block, fan hub, gearbox output shaft ALL have to be parallel to the main shaft and main gear.

[ErichF]

As much as I like our Bergen Observer, I do have to admit that I *H A T E* the engine mount and clutch drive arrangement. The engine mounts are weak, and it's very difficult to hold the engine in perfect alignment while you tighten the mount bolts because you also have to hold a locknut. The setup is just terrible. You have to:

1) Position the clutch bearing block perfectly so that:
a: The pinion engages the main gear properly
b: The pinion is parallell with the engine crankshaft
2) Position the engine in X, Y, and Z axis while simultaneously securing four mount bolts with nuts.
3) Re-check the pinion engagement (it will change just as soon as you tighten the last engine mount bolt)
4) Re-check fan hub and clutch are parallell front/back AND left/right. (it will change as soon as you tighten the clutch bearing block bolts)

If there is ANY misalignment whatsoever, the delrin bushings on the clutch driver bolts will wear through. When that happens, the clutch will come off center, pulling the pinion off the main gear, and VOILA`....Main gear strips.

It's very difficult, and there's no easy way to do it, but the result of any misalignment in this drivetrain will result in the eventual failure of the main gear, or worn/broken clutch. I spent about an hour this morning aligning the clutch on our Observer because I wasn't happy with it, still.

Oh, and here's another gotchya...

You had best get the alingment set correctly the FIRST time. If you don't, the engine mount bolts will compress a divot in the soft G-10 frame plates. If you have to go back and re-adjust the engine positioning, the bolts will settle into those original positions as you re-tighten them. You still end up with the same alignment problem you started out with.

What I would like to see:

A CNC aluminum engine mount plate, with drilled and tapped bolt holes.

Larger engine mount bolts.

Carbon lower frames.

Self-centering clutch driver.

I'm otherwise very happy with our Obsever, and will be ordering two more in the near future. I just wish this engine mounting arrangement was more user-friendly.

Now, I expect to get a buncha "I never have a problem with..." responses, but this has been my experience so far as a new Bergen customer.

[rceye]

ErichF,
You are not the only one -
The only thing I can say is it gets easier to do after a year or so -

I always make sure I have a new set of delrin bushing fitted before I align and set the mesh of the main and pinion gear - this at least keeps the clutch unit really tight and properly aligned with the fan hub. ( if any of the parts are worn its much harder to get everything right )