Jump to content
Sign in to follow this  
cirrusRC

Hacker Motor Pinion repair and ESC settings

Recommended Posts

cirrusRC

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

Share this post


Link to post
Share on other sites
Kyri

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

  • Like 1

Share this post


Link to post
Share on other sites
PeteMitchell

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.

Share this post


Link to post
Share on other sites
Kyri

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. 

 

 

 

Share this post


Link to post
Share on other sites
cirrusRC

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.

Share this post


Link to post
Share on other sites
Kyri

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.

 

  • Thanks 1

Share this post


Link to post
Share on other sites
wixy

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

  • Thanks 1

Share this post


Link to post
Share on other sites
Peter

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

 

 

  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.