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Hacker Motor Pinion repair and ESC settings


cirrusRC

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Dad running a Hacker A10-7L +4,4:1 in his RES glider.    During a recent flight he lost power,   motor runs but gearbox does nothing.    On closer inspection we found the pinion gear has come loose off the motor shaft (interference fit).   First time running with a gearbox so a few questions.

i) doing some reading,  looks like best fix is to use some Loctite 609 or 638 to secure the pinion gear back to the motor shaft and leave for 24 hours.

ii) would i be right in thinking the most likely cause of failure is due to heat build up?    Or has he just been unlucky?  Motor and box is in excellent order and hasn't been abused.  There are holes in the firewall to aid cooling but it's tricky to get airflow to the motor.

iii) is this serviceable by Hacker?   They don't list spares for this motor or box.

iv) the ESC was set up with soft start,  are there any other settings I should have considered when running with a gear box2.thumb.jpg.7d45280ad6c37bd37e9d55b6ae9622c6.jpg1.thumb.jpg.b9d48471379e9a1ce5d83790e67be7d7.jpg?

 

thanks

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To answer your comments:

i. Use loctite 648, for best effect.

ii. Could be heat but also the original may not have been fitted with the right procedure or loctite type (see below). 

iii. You could send it to hacker but for the cost of some loctite and knowing the right method, you can do this yourself, see below. 

Procedure for fitting the pinion (I have done this a lot, if you do it right it works)

Step 1. Check how the pinion locates when the motor has the gearbox screwed on. Is the top of the pinion flush with the shaft, or whatever. Remember this position as it is how you want to glue the pinion on later.

Step 2. Clean the inside of the pinion and the shaft, with acetone. You may have to scrape the shaft and inside of the pinion to remove and residue of old loctite. This ensures no loctite or grease is on the parts you will be fixing. 

Step 3. Put the loctite on a  (clean) screwdriver which is smaller diameter than the pinion, and wet the whole surface of the pinion. Then wet the shaft with loctite too. 

Step 4. Slowly put the pinion onto the shaft, rotating it as you push it on, and once it is at the right place don't move it again.  It is a good idea to do this upside down so that the excess which wants to drip out of the end of the pinion hole, doesn't go onto the teeth. Use a cotton bud to wipe any excess of the shaft or more likely, the top of the pinion. 

Step 5: Don't fit the gearbox yet, and way at least 24 hrs before touching it. This is very important and if you do this, the pinion will more likely stay in place. 

Hope that helps

regards

Kyri

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Don’t think I have ever heard of this fail on a Hacker motor. Had a few myself overtime and they have all been fine. Holes in the firewall don’t have much cooling effect in my experience, unless the motor is being run continuously, so I would not think heat build up was the cause. If it got hot enough to cause the cyano to fail then there would be other serious damage. Was the gearbox dry, or is there still lubricant in it?

As Kyri has said, it is not unknown for the pinion to come loose on any motor and I would guess you were just unlucky.

Locktite is the best glue. They have probably changed spec. since I last bought a bottle (it last’s for years) but the stuff I use is either Loctite 2701 or 648.

To apply it you must make sure that both shaft and pinion are totally grease/oil free. Even oil from your fingers can cause the joint to fail so clean up before gluing with an agressive degreaser.

Usually a soft start is all you need in esc.settings to avoid damaging the gearbox, especially if you use a on/off witch to control the motor. If you have a large dia. prop also using a variable throttle is best to avoid sudden shocks in the gearbox.

Hope that helps.

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Oh yes, as Pete states a soft start on the esc is a great idea, because the torque on the pinion is higher the slower it is rotating, which is the case with bigger props. The soft start helps reduce the sudden torque which can dislodge the pinion. 

The other thing you can do, if your transmitter allows is ramping using the throttle channel - depends on the transmitter capability though. Also  you have to have enough capacity (amps headroom on your esc) to be able to run what is part throttle for a while. It gets the same result which is a soft start from low to full power over part of or a whole second which really helps the mechanical parts last longer especially with glued on pinions.

A simple way is if you have throttle on throttle stick (not a switch) then you can do a manual "ramp" or soft start but this is not as good as getting the esc or tx to do it automatically. 

 

 

 

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Many thanks guys.    Using the throttle rather than switch + ESC soft start.  I'll look into a throttle curve for the future too.     Box wasn't bone dry but equally no major signs of grease - I hear that too much grease is worse than too little.    Guessing any grease will do?

No sign of Loctite residue on the pinion,  I presumed they just used an arbour press at the factory to secure the pinion.

Working out where the pinion fits on the shaft is a little tricky as reattaching the gearbox means I can't see the pinion :)   I'm sure we'll figure it out though.

For the screw thread on the 'motor can' to attach the gearbox - just use blue thread locker?

thanks again.

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The pinion should, when clean, be "free" on the shaft and be easy to rotate and also push back and forth. 

For the pinion position, place the pinion in the gearbox, turn the shaft of the g/b so the pinion locates in the planet gears. It can only go so far. The gear end of the pinion should go in first (the pinion is longer than the gear itself).

Locate the shaft into the pinion end and start screwing the g/b onto the motor. When its fully on, remove it gently and hopefully the pinion will stay on the motor shaft. This may not work if the pinion is too free of the shaft but worth a try. 

Alternatively you can measure it - again by putting the pinion in the g/b without the motor you can see where it is, and place the motor by its side to get an idea where the pinion will be on the shaft.

 

Regarding loctite on the g/b attachment threads - NO as you will struggle to ever get the g/b off in the future. Best thing is to put rubber bands round the motor and g/b and hand tighten as much as you can. That will be plenty.

 

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Had similar happen with one off the first motors I bought  (hacker)

Spent a life time in precision engineering  on checking pinion to shaft fit it was appalling quality  .

Would never buy another hacker product .

I did speak to their quality engineer ,who said they would look into my complaint .

I am also aware off 2 other failures 

G

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I don't think that Hacker are only manufacturer at fault. All the pinions from Hacker and Reisenhaur seem to be no more than just a gentle hand press fit on the motor shafts of HET, Scorpion etc motors as well as Hacker. I would have expected at least a reasonable interference fit so that the pinion would have to be pressed on but none are. Maybe it is because the motor shafts are still 1/8" diameter and the pinion manufacturers are European so don't understand inches!

However if the instruction to use the correct grades of Loctite are followed (not just Threadlock) and the shaft cleaned thoroughly and left to set overnight they do seem to hold OK. Maybe I am old fashioned but I prefer a mechanical fit and not to just rely on glue!

Peter

 

 

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  • 4 years later...
StraightEdge
On 22/10/2018 at 18:27, cirrusRC said:

Dad running a Hacker A10-7L +4,4:1 in his RES glider.    During a recent flight he lost power,   motor runs but gearbox does nothing.    On closer inspection we found the pinion gear has come loose off the motor shaft (interference fit).   First time running with a gearbox so a few questions.

i) doing some reading,  looks like best fix is to use some Loctite 609 or 638 to secure the pinion gear back to the motor shaft and leave for 24 hours.

ii) would i be right in thinking the most likely cause of failure is due to heat build up?    Or has he just been unlucky?  Motor and box is in excellent order and hasn't been abused.  There are holes in the firewall to aid cooling but it's tricky to get airflow to the motor.

iii) is this serviceable by Hacker?   They don't list spares for this motor or box.

iv) the ESC was set up with soft start,  are there any other settings I should have considered when running with a gear box2.thumb.jpg.7d45280ad6c37bd37e9d55b6ae9622c6.jpg1.thumb.jpg.b9d48471379e9a1ce5d83790e67be7d7.jpg?

 

thanks

4-1/2 years on, I've encountered exactly the same problem on my A10-7L with gearbox, i.e. the pinion came lose when the 13x8 prop snagged momentarily when testing on the bench,  but my first problem is how to get the gearbox off the motor.

Do you recall how you managed it?  I have tried a miniature strap-wrench which kept slipping on the gearbox casing, and also tried a pair of mole-grips faced with coarse leather to prevent scratching and crushing but which also slipped.  Is it a conventional thread or a reverse one?

 

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StraightEdge

Update:

Finally got the gearbox off using bare Molegrips with pressure centred on the bronze faceplate to avoid crushing the main casing with only superficial indentation, but astonishing just how tight it was!

PXL_20230305_193330990.thumb.jpg.4281c7fe3b499ba97e6bdbf4423c5a3e.jpg

There is no 'interference fit' at all - the shaft is very loose in the pinion!  Have ordered Loctite 648, will see how this works.

Re the ESC soft-start or throttle curve - do you recall what your eventual solution was?

I'm using Hyperflight's pre-programmed 28A BLHELI-32 ESC.  I don't know what 'start' it is programmed with, but don't think its 'soft', so I'll have to programme in a throttle curve with a gentle ramp-up.

I certainly don't want to have to mangle the model nose (Eli F5RES) to remove the Hacker if this happens again!

PXL_20230228_114257606(1).thumb.jpg.d9a864ccd118eeedec1b2d496e3f9eb3.jpg

 

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Dad can't remember how it came apart but he said it was easy 😃

He had to repair/glue it twice!   It's been ok since (touch wood).

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PeteMitchell
2 hours ago, StraightEdge said:

I don't know what 'start' it is programmed with, but don't think its 'soft', so I'll have to programme in a throttle curve with a gentle ramp-up.

It is also a good idea to programme  your esc for a slow stop rather than a hard stop. If you are using a large'ish  dia prop, a sudden stop can have the same effect as a fast start.

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StraightEdge

Good point Pete

In fact I emailed the Hacker service guy for his advice and he replied this morning:

"We use Loctite 276 for glueing the pinion.  Degrease pinion and motor shaft before you glue the pinion, make test-run only the next day.  Set your controller to soft start and soft brake. Hard brake could be the reason for the loose pinion."

As I've already ordered Loctite 648 (High Strength Retaining Compound... Common uses include sprockets, gearbox shafts, fixing rotors on rotor shafts and similar applications) I'll start with this.

Slight problem with the soft-stop.  My application is F5-RES with throttle on slider cut off by Altis Nano.  The ESC is shipped pre-programmed by HyperFlight with 100% hard-stop.  So looks like I'll have to buy and solder up an Arduino Nano then learn how to use the programming software.  Fortunately there are links to files which link to a video:  hyperflight-28a-blheli-32

Screenshot2023-03-06at08_19_00.thumb.png.b549b3989ab20234496c5811fb841428.png

From HyperFlight's page, I see the following already pre-programmed in:

  • "Brake On Stop" set at 100%.  Re-set it to how much?  ...say 50% or 70%?
  • "Rampup Power" set at 80%.  Does this need changing, and if so what to?
  • "Maximum Acceleration" set at Maximum.  Does this need changing, and what to?

Eventually I'll be able to finish actually building the Eli, let alone being able to fly it...! 😅

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Some transmitters allow you to programme a slow start and slow stop. Any transmitter running OpenTX will have this function.

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StraightEdge
22 minutes ago, cirrusRC said:

I did a post on RCG Medina thread for programming esc with arduino.   Ping me if you need any help.

 

Thx, saw that the other day, including the video that the HF documents link to, which made me realise that getting involved with programming via an Arduino isn't that daunting.  Just ordered a Nano off eBay for under six quid.

 

12 minutes ago, SteveH said:

Some transmitters allow you to programme a slow start and slow stop. Any transmitter running OpenTX will have this function.

Yes, but I'm assuming that if the motor is cut off by the Altis (which it will be in F5-RES) then the matter becomes beyond the control of the TX...?

PS - just seen cirrus ask the same question...

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What's the benefit to a geared motor setup like this? Why not just go with the smaller prop and non-geared motor? My guess is that a bigger longer prop will be more efficient and less noisy, is that right?

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