Heated Servo

[Paul M]

This may be a bit of an odd question, but hopefully someone can give me an answer!
About a year ago I fitted a radio control system to my live steamers Accucraft Lynn. I placed the servo on the floor of the cab out of the way and quite discrete. Unfortunately the said servo has now failed, a spindle snapped. Could this be due to the heat of the floor and/or general crud that seems to collect in every surface? I must admit to taking the view that I put it in a silly place to start with, but any comments would be gratefully received

 

[G-force1]

A picture might be of use Paul. Difficult to coment without one.

 

[PhilP]

Difficult to tell without seeing it, and knowing which 'spindle' you mean?

Might have been something in the gear-chain, jammed, and the motor sheared something? - Though I doubt this far a small (9g?) servo..
Could also be the servo was being driven hard against an end-stop, or some external limit of travel, hence putting a strain on the gearing??

 

[Paul M]

Unfortunately I didn't think to take any pictures. I don't think it was due to being driven against a backdrop stop (I could be wrong ) but when I reset it up I'll be very careful! The gearight which broke was between the worm drive on the motor and the main gear chain, it was very small and didn't look to be manice enough

 

[Tony Walsham]

What brand was the servo?
Some brands are stronger than others. I recommend Hi-Tec metal geared servos. More expensive but more reliable than the el cheapo brands you find on the Net.

 

[Paul M]

Gents, here's a dodgy picture of the offendingredients beastie. As you can see it's the link cog between the main drive and the rest of the gear chain. It's a Newpower servo, bought from a proper source.

 

[Greg Elmassian]

so the snapped spindle disengaged the motor from the rest of the gear train?

 

[Paul M]

Yes, and has caused all sort of grief

 

[Greg Elmassian]

I have to admit, while not super experienced with servos, I have seen my share, and that's unusual in my book.

Greg

 

[Zerogee]

Not quite sure I understand what I'm looking at in your pic, Paul - obviously I can see that the motor gear is no longer meshing with anything, but has the rest of the geartrain somehow moved out of contact with the motor gear, or is there a gear completely missing in the pic?

Jon.

 

[Tony Walsham]

SNIP

Would be prudent to ask amongst the Live Steam Fraternity which Servos they are using for their control system, and follow suit...…..

I would urge you you to go back to post # 5 for my advice!!!

 

[stockers]

Yes Tony - one of the established names - Hitec, Futaba, Groupner.

 

[Zerogee]

Accucraft.de (MBV Schug) recommend HiTec metal geared servos for putting RC into their live steamers, and provide mounting brackets to suit. The reverser servo in my Wonky (Saxon 1K) is an extremely thin special type designed (I think) for control of flaps in RC aircraft.

Jon.

 

[Paul M]

Thanks for all your help on this. Talking to a retailer, he aid that all metal geared servos have some plastic gears, which seems a bit odd. I'm now making a mounting bracket and am going to put it where I don't need to take the engine apart to fix it if it goes again!

 

[PhilP]

Thanks for all your help on this. Talking to a retailer, he aid that all metal geared servos have some plastic gears, which seems a bit odd. I'm now making a mounting bracket and am going to put it where I don't need to take the engine apart to fix it if it goes again!

That is probably a good idea, but I think the gears tend to be Nylon?? - I doubt they would melt at any sensible temperature on your footplate? I think this was a mechanical issue???

 

[Greg Elmassian]

I think excessive heat and pressure can weaken the gears... the nylon will soften a bit.

 

[Paul M]

I've taken on board all yourights comments, and am now half way through making a bracket. Im also endeavouring to make it so that I don't need to take the locomotive apart if it ever needs replacing. Also seriously considering changing my Newpower servo to Hitech. Thanks for all your comments and help.

 

[Paul M]

Not quite sure I understand what I'm looking at in your pic, Paul - obviously I can see that the motor gear is no longer meshing with anything, but has the rest of the geartrain somehow moved out of contact with the motor gear, or is there a gear completely missing in the pic?

Jon.

Right, OK, unusually for me, I taken on board all the advice given and made up a bracket, purchased and fitted a new Hi-tech all metal servo and put it all back together. As you can see from the picture it's not too obvious in the cab. Hopefully testing tomorrow will be successful. If not someone will earn merit marks for taking it away and putting it right for me!