Prerotator bendix

[Mike Leimetter]

I have a SC rotor head and I lubed it per the manual. While ground running my RAF, it’s got 1.3 hrs on it so far, I did a test run on the prerotator. It spun, seemed to work ok but didn’t get very fast. After shutting down and checking the prerotator it seems to be stuck in the active position. Help! What do I do now? I tried but it won’t back down.
Mike

 

[gyroplanes]

Hello Mike, Maybe The Bendix on your gyro is unmodified like the ones I used. Stock Bendix drives have a pin and spring that locks them until the rotor hits enough RPM to kick them out like a car starter. I'm not sure if that works or not. Maybe someone else knows. I bought Bendix drives from the manufacturer disassembled and discarded those parts.

 

[Sv.grainne]

Mike, post a photo and will see if it's the sme thing I've seen on the Bendix unit on Aviomanias.

Bobby

 

[Mike Leimetter]

Mike, post a photo and will see if it's the sme thing I've seen on the Bendix unit on Aviomanias.

Bobby

Thanks guys. This is it. SC doesn’t answer their phones. It was not engaged before I ran it. The head spun freely. Could too much grease do that?

 

[Sv.grainne]

Can't see any of the mechanism.

 

[Jamie Cleary]

Were you spinning just the Rotorhead with no blades ? if so it won't go very fast and without some resistance the Bendix may not kick out .

 

[Gyro Technic]

Mike,
We supply the Bendix units with the latching pin removed just like Tom Milton mentioned.
I find that people put WAY too much lubrication on these.
Grease will get stiff and cause it to hang up.
You might want to take it apart and clean it up in a parts washer.
Then, I recommend only a light spray of graphite or silicone.
Denis

 

[Mike Leimetter]

Mike,
We supply the Bendix units with the latching pin removed just like Tom Milton mentioned.
I find that people put WAY too much lubrication on these.
Grease will get stiff and cause it to hang up.
You might want to take it apart and clean it up in a parts washer.
Then, I recommend only a light spray of graphite or silicone.
Denis

Thank you all. I know the grease didn’t get stiff because I just put it in 10 mins before. The instructions say to grease it until it comes out the top. It never did lol. But I know there’s definitely a few pumps in there. Unfortunately I think Dennis is right and I’ll have to take it all apart, which means removing the rotor head and dismantling that also.

 

[AviomaniaTexas]

Nicolas Karoalides from Aviomania, recommends using ceramic grease on the bendix.

 

[Sv.grainne]

Nicolas Karoalides from Aviomania, recommends using ceramic grease on the bendix.

That's because he uses a totally different Bendix arrangement. Grease is critical because of the Aviomania similar metals in friction contact. These other types use roller bearings and friction is way less an issue.

 

[MilesW]

SC supply the bendix modified exactly the same as Tom and Denis. Of course it is possible one has slipped through the process before being incorporated in your head.
An oversupply of fresh grease should not cause a hang up. Different story as it dries out. Best to use just a little. A light spray of MC chain seems to work.
The SC head is adjustable for bendix to ring gear gap (backlash). On the tight side it can still engage but may hang up. Too loose and you will chew out gears pretty quick.
Use a screwdriver (gently) to try and retract the bendix gear. If it retracts it is most likely the backlash. Adjust accordingly. If there is strong resistance and it doesn't retract, it is most likely an unmodified bendix. Remove and modify. I am sure Tom or Denis would talk you through this procedure. Fiddly but not difficult.
You do not have to remove the head to remove the bendix. It comes out very simply from the bottom. Take careful not of the retaining screw positions.


Miles

 

[Mike Leimetter]

Thank you Miles. It does not move at all, only spins. SC recommends chevron grease. I followed the instructions exactly but obviously it’s too much. I will attempt to take it apart next week.Really appreciate all your input and help.

 

[Mike Leimetter]

Ok. As usual, which is why I love this forum, you all were right. I apologize and a lot of this is just from me not knowing the nomenclature. I was able to remove the Bendix and as y’all said, it was packed with grease. I managed to remove the bulk of it and it now moves easily. Thank you all so much your a wealth of knowledge!

 

[gyroplanes]

The Bendix is the same as they used on car starters years ago. You don't grease a starter Bendix... but the Bendix manufacturer does now recommend LPS Magnum spray, only.

 

[Mike Leimetter]

Well I learned my lessons that for sure. I’ll order some LPS Magnum and chuck the grease. I wonder why SC would recommend that and even put a zero fitting on top.

 

[gyroplanes]

If the Bendix shaft turns in a bushing, then grease IS required, all the rest prefers LPS Magnum. Lift up the Bendix outer, it will turn as you do, spray the very coarse threads with the LPS, also all of the gears..

 

[Mike Leimetter]

If the Bendix shaft turns in a bushing, then grease IS required, all the rest prefers LPS Magnum. Lift up the Bendix outer, it will turn as you do, spray the very coarse threads with the LPS, also all of the gears..

Thanks Tom yes it definitely turns when it’s lifted.

 

[gyroplanes]

Thanks Tom yes it definitely turns when it’s lifted.

When it's lifted, does it lock in the up position? It should free fall.

 

[Mike Leimetter]

It did until I got all that damn grease out lol

 

[blacktail]

Ngl1 because it is thinner and just a little bit