Tail shaft drive mesh adjustment and clutch bell free-play?

[Gigi]

Last week, I finished the "overhaul" of my Bergen Intrepid. I replaced all the faulty bearings, changed the main gear, the clutch shoes, rebuilt the carb, installed all new cyclic and collective servos, and fitted a new canopy. Unfortunately, I ran into a problem, and have two specific questions:

1) I destroyed the tail gear teeth on the main gear in less than 2 minutes of running. Obviously, it was improperly adjusted, and it's my fault. The teeth look rolled over, which leads me to believe there was too much lash. I had adjusted the short shaft with the pinion to be straight with the boom. That's clearly wrong, I can see that. For my next try, should I just push the shaft down at the rear? Note that I have the optional bearing on the front of my short shaft, in front of the pinion, and the hole in the bearing holder isn't slotted. So my question is, should the short shaft and the boom make a slight angle? Do I just push down on the rear of the short shaft to put as much of the teeth of the pinion into the main gear? Or is there another procedure? The instructions ask to make it drag slightly only.

2) I have a .020" gap between the top of the pinion gear on the clutch bell and the bearing holder which is located above the pinion. Is this normal? The motor is pushed upwards as much as possible, and the bearing holder's holes are slotted only forward and backwards. The new clutch seemed to work fine, I got the heli to hover a couple of times prior to the tail drive failing. But the gap is very noticeable if I move the clutch bell up and down. Is there something I need to do, and if so, what?

Thanks,

Gigi

[3drcheli]

Hi Gigi,

Looks like you have done a nice job overhauling the Bergen.

1. Those teeth look very rounded, so it was a long way out of mesh. First point I notice in the picture is that all those screws are loose - did you back these out afterwards ? I wouldn't have thought it is the angle of the takeoff gear as it doesn't allow that much travel to get it so far out of mesh, especially with the front support bearing. Was the main gear pulled right up to the bearing when you tightened the main shaft collars, because it looks to me like the main gear was too low? Or the lower collar wasn't tightened up allowing the shaft to move down when negative pitch was applied with it spooled up?

2. I use green loktite (permanent stuff) to glue the clutch pinion gear into the bearing above it. If you don't do this it can wear that bearing out fairly quickly. This removes that free play and stops the clutch bell resting on the clutch all the time.

Kevin

[kelly steed]

when you get your new main gear,start with main gear ,main shaft,main shaft bearings,and your collars,if your going to do any ap work order thrust bearing,it goes just below your top main bearing,install all parts and make sure you have no play when you try to move your main gear up and down.next make sure your tail transmission has no play when you try to move the cupler back and forth,if it does theres a nother fix for that.install tail trans ,you may have to use slite presure to get good mesh,as you turn the main gear when checking mesh you will notice a tight spot,that spot will be zero back lash,you want to go past that spot with very littel binding,but you should still notice some draging when going past that spot.next order a collar that goes on the top of your triple bearing block,this hold the clucht and tripple bearing block tight togetther,you may have to tap the pinon very lighty so it seats in that bearing on the block,when this unit is to gether you should be able to hold the tripple bearing block in one hand,and with the other try to move the clucth bell,there should be no movment

parts you need thrust bearing for ap work
collar for top of tripple bearing block

main shaft assy frist--------tailtrans next------tripple bearing block installed then your engine if you need help with bearing block and engine pm me these steps of alingment take time,but it will be some time befor you do them agian.

[v22chap]

Also check to make sure your bottom bearing block is in right ,,,if it is in upside down this would make your main gear ride lower and make it so you couldn't get the tail pinion drive gear down far enough to mesh right !!!???? The whole pinion gear should mesh with the crown gear of the main gear and do it easily.
Larry

[Gigi]

Hi, guys, thanks for the replies.

3drcheli, I did back those screws out myself, they were tight on the heli. I stopped to take the pictures half-way through the "flipping" of the main gear, to use the teeth on the other side.I don't know if maybe I didn't tighten the lower collar enough, and it pushed out, but I doubt it, as I didn't go out of hover with the machine, as it was not tuned yet, the needles were rich.

Kelly Steed, I'll make sure the collars are tight. I think I simply didn't push the pinion down enough on the main gear, because I wanted the shaft to be straight. I already have the collar on top of the clutch shaft, if that's what you're refering to. I'll have to see why I have the gap...

V-22chap, thanks for the heads-up, that is one part I had removed. Mine has a special "big bearing" in there, which Chris was kind enough to send to me. I'm pretty sure I put it back the way the book says, but who knows... It's a good theory, at any rate. The whole pinion does mesh, but the pinion shaft looks like it's at a slight angle instead of straight. And the main gear is all the way up, that's a fact. But I'll look into it.

Boy, for us fairly-new heli pilots who have only built a Raptor, this machine is not exactly a piece of cake to work on or dial in... :roll: Hopefully, I get it back in the air before too long.

Thanks for the help, it's appreciated!

Gigi

[Gigi]

Well, guys, it's with great pleasure that I report that the helicopter was succesfully test-flown on saturday. I had two flights, during which I did some motor tuning. For some reason, I had a bit too much pitch at the top end, despite the pitch gage saying 10 degrees. I went back to the field today, after making the vertical pushrods which go to the poscicle bars about two turns longer.

The helicopter flew very well, but one thing is bothering me: It seems to burn a lot less fuel than before. I have the low needle on the W167a carb at 15/16 and the high at 1 1/4. If I richen the low, it four-strokes quite noticeably. That's about where the needles were before (actually 7/8 on the low). It climbs really well. I even think I should close the low a bit more, but I think I'll leave well enough alone. There were two changes made to the motor: I've put on the aluminum carb spacer, and after reading up quite a bit on it, I've gone from 5 oz to 4 oz per gallon. It seems to work all right, other than the fuel not going down like I remembered. Using the stock tank (16 oz, I guess), I used to get about 12-13 minutes of flight. Now, 16-18 minutes later, it's still has a 1/4 tank left... Is that the way it's supposed to be?

Thanks,

Gigi

[kelly steed]

a lot of factors come into play here,do you have garrys set up video,whats your head speed a 1/4 stick,and hover,its possible you may be loading your motor just alittle to late and getting into your high needle at hover.

[cbergen]

He's complaining that he's getting MORE flight time!! :arggg: :lol: :lol:

Just kidding Gigi!!

In all actuality, you shoud typically get up to 30 minutes of run time, depending on how you're flying it.

The fact that you were only getting 12-13 minutes previously tells me that you were probably way to rich, or running the wrong pinion gear, or loading the engine too much with too low of a headspeed.

With the G26 in my bird, I flew in the night fly at IRCHA. I started with a little more than half a tank of fuel, flew for maybe 5-6 minutes. The next morning I did another demo with the bird, did not refuel as I STILL had more than a quarter tank of fuel onboard. This is with the same size tank and a larger bore carb that I suspect would use more gas...

[kelly steed]

Hey gigi you better go with what cris tells you,I forgot I have not flown this summer with my cam gear off.I get 10 min with not going below 1/4 tank.my chopper can burn two gal in six hours pretty fast when taking pic.

[Gigi]

Hi, guys,

thanks for the replies. I hadn't checked this forum in a few days.

I do have Gary Travis' video, and I did set up the heli using it.

In my defense, the needles were set pretty much the same way before... I don't know if it's the lower oil content I'm seeing. The governor was also at 1,650 and 1,750, whereas now it's set for only 1,700 (I've put it on a two position switch instead of the idle-up switch, like on my Raptor). It's possible that it burned less fuel than I'm remembering... My timer is set for 15 minutes and I got at least that much out of it, but it was nearing empty (say 1/8 left). Now, there's definitely more like 1/4 left, even if I fly longer.

You're right, Chris, I'll stop complaining :noteworthy

I am so happy the Bergen is back in the air! I am toying with the idea of putting one of Raja's on-board generators on it.

Gigi