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Bergen R/C Helicopters > Main gear question...
 
 
coop
Senior Heliman
Location: Bainbridge, NY

Hi Guys....I noticed tonight after a flight with my Intrepid that there was some metel filings on the top of my main gear. After inspection, I noticed that the heads of the screws that hold the main gear to the hub were just touching the bottom of the tail gear support housing. I have the correct bolts installed that go in here with the tail support upgrade. I did just recently replace the main gear. I have the correct mesh, I am wondering if maybe the gear is machined to thick in this area, causing the heads of the bolts to be to close to the support. Anybody else had this problem?....Coop
07-04-2003 Over year old.
 
 
Al Magaloff
rrMaster
Location: 12,199 Posts- Enough Time Wasted. See Ya!

Hey Coop. Do you have the special low head screws, part #5308?
07-04-2003 Over year old.
 
 
coop
Senior Heliman
Location: Bainbridge, NY

Yes, I have the special screws, this heli is 4 years old, never had this problem before until I changed the main gear. I also noticed that the set screws holding the tail pinion gear on are touching the top of the main gear, just slightly. I must have a gear that is machined a little thicker than it is supposed to be....Coop
07-04-2003 Over year old.
 
 
Al Magaloff
rrMaster
Location: 12,199 Posts- Enough Time Wasted. See Ya!

Yeah, must be. Might have to give Larry a call. Try turning the gear over, to see if it is symetrical or not.
07-04-2003 Over year old.
 
 
coop
Senior Heliman
Location: Bainbridge, NY

Thanks for the replys Al, I'll turn the gear over as you suggest, I was just wondering if anybody else has had this problem.....Coop
07-04-2003 Over year old.
 
 
Al Magaloff
rrMaster
Location: 12,199 Posts- Enough Time Wasted. See Ya!

Coop, is it one of the machined Delrin gears, or the standard gear?
07-04-2003 Over year old.
 
 
Malorie
Elite Veteran
Location: Paw squared, MI

It is possible that the new machined gear is thicker. The machined one is not symetrical and cannot be turned over. I will bring this trouble to Larry's attention. I tested the prototype gear and didn't have this trouble. The tolerances in that area are pretty close so it could have gotten thick enough for that to happen. I know one of the things that was being worked on with the new gear is the angle of the crown gear. With the molded gear, it was not quite the perfect angle for full gear mesh. When they changed that angle, it could have brought the transmission lower into the gear and caused this trouble. The prototype gear did not have this adjustment.

Let me know if anybody else is having that trouble with the new gear.

Thanks,
Malorie

Life's a journey, NOT a destination.
07-04-2003 Over year old.
 
 
MikeS
Senior Heliman
Location: So. Calif.

"I also noticed that the set screws holding the tail pinion gear on are touching the top of the main gear"

If this is true you have tooo long of set screws in the pinion!!!!
07-05-2003 Over year old.
 
 
coop
Senior Heliman
Location: Bainbridge, NY

Malorie....How do I know if I have the new machined gear? The one I have looks like the original, it does have the mirror image on the other side, indicating to me that it can be flipped over. ...

Mike...The screws in the pinion are the ones that have always been in there, I have never changed them, so that doesn't answer my clearance problem....Coop
07-05-2003 Over year old.
 
 
MikeS
Senior Heliman
Location: So. Calif.

I'd say the gear is not one of the newer ones they cannot be flipped. And don't take it wrong but just because the screws have been like that forever doesn't mean they're right.... They should not be protruding past flush of the collar they thread into.
07-05-2003 Over year old.
 
 
GMPheli
Veteran
Location: W. Bridgewater, MA USA

Coop:
I have an X-Cell main gear on my Intrepid. I had to counter sink and use flat head screws on the main gear to prevent them from hitting.
07-05-2003 Over year old.
 
 
Malorie
Elite Veteran
Location: Paw squared, MI

The new gerar is single sided.

I just checked the new gear and it isn't a problem with that.

Check your set screws to make certain that the one that should be in the hole in the shaft is where it belongs. If the pinnion has slid back a bit, that would also lower the front of the transmission. They shouldn't be sticking out of the gear as mentioned earlier. The one in the hole should be a 4mm and the one not in the hole should be a 3mm.

Keep us posted,
Malorie

Life's a journey, NOT a destination.
07-05-2003 Over year old.
 
 
FalconPilot
Senior Heliman
Location: upstate, NY

New Gear expanding?

Malorie,
I have the new gear. I set the mesh so it was moving freely with no slop. After flying the chopper hard for 3 min, I set it down. When I let off the collective and throttled down, the tail stopped instantly! The main mesh was VERY tight. I reset things and flew again. It came back a little tight so I reset things again. This time it came back ok.

After letting things cool, I checked the mesh one more time. It was VERY loose! It seems the gear expands when under heavy load. Did you notice any of this in your testing? Larry said he had not heard of this problem.

Be advised, I am running a G230 cyl on the g23 case that Larry modified for me. It stresses the drive train. This is a continuing test Larry and I have been working of for 2 years. Lets just say it doesn't lack power!

Chad
07-12-2003 Over year old.
 
 
Malorie
Elite Veteran
Location: Paw squared, MI

I ran it on the G26 through a lot of high load stuff. Stuff I normally don't do to my heli. I hadn't noticed anything like that. Not to say that it couldn't happen, just that we did quite a bit of high stress testing with good results.

Larry is currently running the double version on his twin with similar results.

A few things you can look at to make certain they aren't adding to the diagnosis.

Make sure your collars aren't slipping on the mainshaft. I have been running a drop of LocTite between them and the mainshaft. I have had them shift in high G maneuvers before.

Also, make sure your tail transmission is out of the way when you set your collars in place. This will assure that the auto hub is riding on the bearing race instead of the gear/autohub unit riding on the tail bevel gear.

Make sure both mainshaft bearings are completely seated in the bearing blocks. I have noticed in the past that the more worn ones can move a few thousandths in the block. Then after you set your mesh, they can move back under load, changing your gear mesh.

Check these few things and do some more flying and see if that cures it. If not, let me know and we'll confirm your findings here and see what can be done.

Thanks and keep me posted,
Malorie

Life's a journey, NOT a destination.
07-13-2003 Over year old.
 
 
FalconPilot
Senior Heliman
Location: upstate, NY

Thanks Malorie!

Part of the problem was the tail drive to main gear setup. I did have it a little tight. The other problem is that the gear DOES expand!! Larry just varified it with his twin. We have some work to do to get things set up just right. It seems if you adjust the main lash while warm, all is good.

On the plus side, the new gear seems to be holding up very well. With all the torutre I have put it through, It still looks new. The old gear would have been hurting! (1/2 gal in about a week), over 50% at WOT (I like to fly fast)

Larry just sent me the bore up kit for my g23 modified case. (it uses the (G230 RC cyl). Now we will see what the gear can really handle! (25.4cc, big ports, high RPM, small pinion to get the rotor speed right, Now if I could only mess with the timing, my 14lb chopper might just get into retreating blade stall in level flight!)
07-17-2003 Over year old.
 
 
Malorie
Elite Veteran
Location: Paw squared, MI

He He He, you do like to go fast.

Glad to hear you zeroed in on it.

Life's a journey, NOT a destination.
07-18-2003 Over year old.
 
 
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