550 E despair

[stanley]

My last 3 flights with my 550 have all ended with the main gear stripping
the first one was with a HK main maybe substandard quality I thought
the next two flights it has happened again with Align maingears ?
I have not changed anything in my set up
I am running a Scorpion 4025 1100 KV motor 16 tooth pinnion
Hobbywing 100mha ESC 550 mains Idle 1/2 flat 80%
I am not an extreme flyer (flips rolls loops etc )
motor/gear mesh is correct TX is a DX7
PS running a"ye olde flybar"
any input gratefully recived PPS need help this is getting expensive

[johnsandywhite]

You could updgrade to the M08 gears stanley. The only time I have stripped a set was when I crashed. They are expensive, but worth the money. See you Wednesday.

[stanley]

Morning John yes 25 euros or 200+ bling tokens ? definitely the solution (the flight was going so well too )

[PKNEC]

I can only think that the pinion is not meshed correctly with the main gear or if looks ok when its static then its moving when underload.
Check the motor mount screws and re loctite.
Also check the oneway bearing isnt on its way out.

[Si Goodchild]

Agree - poor motor pinion mesh has to be the most credible cause. I've been there and had a motor-retaining screw work loose, strip the gear and piro to the ground. Nasty.

[PKNEC]

Some more info here stanley although trex 500 but same problem
http://www.rcheliaddict.co.uk/t-rex-...main-gear.html

[highlightshadow]

Check the insides of the frames ... any signs of white powdery residue .... i found that on one of my heli's after i lost a main-gear ... was definitely meshed too tight

Now i replaced the gear and backed off the mesh i have zero issues and a quieter system

[RcRotaryMadness]

I'd recommend using the Align Gears or better - not HK ones.

As said sounds like theres an issue with the gear mesh,

1) are both you main & pinion gear the same MOD?
2) When setting the mesh, rotate the main gear to find the point where it is tightest with the pinion, use this as your setting point, use a strip of newspaper, feed it between the pinion & main gear, push the two together (but not too firmly!) - Tighten up screws, all screws should be thread locked and tightened up so not to come lose or move in any way - Electric motors can produce an enormous torque kick when they want to so they've gotta be tight.
2b) Once set, rotate the motor case manually, the strip of paper should pass through and look corrugated but not torn up, if its ripping it could be too tight.
2c) Check the teeth on your pinion are blunt & not sharp.
3) Check your autorotation gear for smooth movement.
4) Double check all your settings, especially the ones in the ESC, you never know if something weird has happened and its changed a setting.
5) Check your motor shaft isn't bent (spool up with no pinion, see if the shaft wobbles)
6) Check the rest of the drive train for anything that could induce a load on the gears or a lock up - such as binding, shaft bearings etc - if they're on the way out the main gear could be moving around or the bearing itself adding to the load... So check all the drive train from the main gear to the rotor head/blades.



As said, any white powdery residue on the inside of the frame is a sign of the gear being eaten, either by mesh problems or sharp pinion etc.

[stanley]

Motor is ridged on the mount and locktighted same for the pinnion grub screw I will check the OWB after work this afternoon
PS no signs of any maingear DNA around the inner frames tHANK YOU ALL for the input
PPS its only started to misbehave since I have started to use a LiPo from a Toyota Prius

[PKNEC]

Do you notice it loosing a bit of power then ramping up again.
Just a thought that if it is switching on/off very fast it might be overloading the pinion head and stripping the teeth?
Go back to your old batts and see if it does it then.

[stanley]

After checking the complete drive chain front to tail I have discovered that the mainshaft can move verticaly

[stanley]

After checking the complete drive chain front to tail I have discovered that the mainshaft can move vertically maybe 1/2 mm so maybe in transition upright to inverted and back the main gear could be moving enough to self destruct on the tapered/lower section of the motor pinnion ?
as I recall my last "extremely fast landing" was with the heli comming into the inverted attitude just enough play to mesh with the lower pinnion and chew up the main gear ? so I will do a complete rebuild re shim the mainshaft and try again once again thanx to all for your input

[iceuk]

Something has to be wrong with heli. You dont strip 3 main gears for no reason. Go over heli with a fine
Tooth comb check and recheck

[RcRotaryMadness]

Do you mean 1 to 2mm of play or half a mm?

Half a mm of vertical play in the main shaft is very minuscule and wouldn't expect that to be a problem, 2mm of movement is too much.

yeah clearly something isn't right and probably best to rebuild the drive train checking every part, the autorotation bearing is a must.. Worth checking your main shaft isn't bent too. Tail shaft too.

also check if something is binding on the main shaft, if the stripping is happening in extreme manoeuvres perhaps that is a clue, an issue with the swash perhaps? Worth checking its bearings are working right too!

[stanley]

I am talking about half a mm I do recall a past post about shortening the Scorpion main shaft to improve pinnion mesh
on my 600 E with a 600 BX fitted the mainshaft/pinnion mesh is meeting in the middle of the pinnion as im rebuilding my heli I notice with the scorpion motor the contact is very close to the bottom of the pinnion so I am going to take 2mm off the motor shaft to drop the pinnion thus improve any doubt about a constant vertical mesh "to be continued "