[Flyin High]

I recently bought 4 Hitec Hs-5475HB off an RCC member (they were brand new) I have heard people saying that they are failing a lot for people. I would like to know, has anyone HERE had first hand problems with these servos. Also who has them and have had no problems?

Thanks in advance!

[treecutter]

https://www.rccanada.ca/bb/viewtopic....866&highlight=

[Noin]

If you search you will probably find the press release about carbonite gears from Hitec themselves. They have warned against using them in high load applications. What is happening is the gears are more brittle than expected and they are chipping. I have read this release myself, I just can't remember where. They are fine for about 60 size or under but not anything above, if I remember correctly.

[Ramz-to-tha-Z]

wow...did Hitec ever screw up on this one!!!

[x-Turd]

Hi Bobby i would e mail Hitec and ask them there just might be an updated gear set

[Kevin McGrath]

I have had three 635s fail..........ie teeth were fractured from the gear wheels under what I would consider normal loads for servos in this torque range.Crashes and rough service were not factors.
The dealer where I bought them could not get replacement gears so two of the servos were sent to HITEC in California at my cost and Hitec replaced my servos with new ones and paid the freight.
They have offered to repair/or replace the third one in the same way.
There is no metal or nylon gearset that will replace the Karbonite ones.
Hitec did say they would consider an upgrade at my cost but only on failed servos when I sent them in.
I have read everything I could find on this subject and it appears the Karbonite material is very brittle and will fail at all but the lightest loads.Too bad too because the servos are smooth and are supposed to wear better than nylon or metal.........
I think Hitec have a major problem here but I dont know what they intend to do about it in the final analysis.

[Flyin High]

Ok thanks for the help guys. I sent Hitec an email, and I will tell you how it goes.

[Flyin High]

Hello Bobby,

We are suggesting following the 12lb rule. This means if the plane is
over 12lbs that you should gang up servos per surface. I would always
suggest going with metal gears servos with larger planes.

Thank you,

This was there response to me

[Guest]

Originally Posted by Kevin McGrath

I have had three 635s fail..........ie teeth were fractured from the gear wheels under what I would consider normal loads for servos in this torque range.Crashes and rough service were not factors.
The dealer where I bought them could not get replacement gears so two of the servos were sent to HITEC in California at my cost and Hitec replaced my servos with new ones and paid the freight.
They have offered to repair/or replace the third one in the same way.
There is no metal or nylon gearset that will replace the Karbonite ones.
Hitec did say they would consider an upgrade at my cost but only on failed servos when I sent them in.
I have read everything I could find on this subject and it appears the Karbonite material is very brittle and will fail at all but the lightest loads.Too bad too because the servos are smooth and are supposed to wear better than nylon or metal.........
I think Hitec have a major problem here but I dont know what they intend to do about it in the final analysis.

Mmm, super strong material that is ductile Yet cheap enough to withstand the cutthroat hobby business

Me thinks it doesnt exist

This is not just a problem with servos....many high strength materials have problems with fracture toughness unless you go to the exotic such as Inconel, Incoloy, MP35N, ENXX series....but they are a bit $$$$ Gears are usually carburized (case hardened, 3312/9310 steel) or the like to give high surface hardness and a relatively thick (0.050") very high strength case, yet leave a lower strength but fatigue, crack resistant core. Then the design of the gear it self is critical....sharp corners, load angles...man not straight forward stuff

Thats doing it will alloys, which are uniform and predictable by all accounts.....plastics, composites....that takes the science out of it right there and leaves it in the hands of chemists!!! Ahhhhh!!!!

I cringe when I hear material names like Karbonite.....like man what the hell is that!!! Would give me a much better warm fuzzy if they would use a common trade name so I could get the properties of it.

Good, that pretty much wasted the last bit of the day LOL

[Kevin McGrath]

Some of Hitecs Karbonite servos develop as much as 144in/oz of torque at 4.8 volts.
Using their 12 lb. rule that means I have to gang two 144oz servos on an aileron on a 15 lb model?They must think We have been taking stupid pills
I have seen reference to this 12 lb rule before and frankly it makes Hitec look very silly and is doing real damage to their normally very good service and quality reputation.
I have no way of knowing what kind of dollars are involved but the ethical way to handle this disaster is to pull the Karbonite servos off the market,admit they screwed up and quickly develop nylon or metal gear replacements for the Karbonite ones already in the hands of customers.
Their approach so far doesnt fill me with faith that anything will get done,and the really sad part is that they are still selling the servos with these disastrous gears in them and contributing to the destruction of modellers aircraft.