N20 motors - Railway Modeller April 2018

[hayfield]

On 07/02/2022 at 01:42, Rod Hutchinson said:

Is you process something like the following:

1. Remove shaft from housing, 

2. Press off drive gear, 

3. Replace shaft with one of desired diameter, 

4. Add a bush to support original drive gear, 

5. Stick it all back together?

 

On 08/02/2022 at 15:28, tomparryharry said:

Hi Rod. Yes, that's basically it. I used a 1/8" Romford axle to replace the final gear axle, and re-assembled. If you're careful enough, there is a possibility to retain the 2 hollow rivets which pass through the gearbox.  If this is the case, it 'should' provide ability to accurately retain the motor on station.

 

 

Like Tomparryharry I am also new to this motor

 

 

Not shown on my photos is the screw and rivets on both sides of the gearbox but I am being a bit thick.

 

Firstly to change the axle do I have to take the the gearbox side off and or the other side of the gearbox. Or can one simply push it out of the gear and gear sides

 

You then talk about bushing the axle, I assume you bush the gearbox sides

 

I am working to EM gauge so I have plenty of side play as the gearbox is 10mm wide, I assume though as the axle is glued to the final gear I would have to make it removable from the chassis using hornblocks ?

 

Would the 3mm axles fit Gibson wheels?

[ianLMS]

I have just succesfully replaced the axle on one of these lovely N20's with a Markits Alan Gibson 1/8" axle. In the end, i reamed out the hole to take the new axle and added bearings as spacers, the soldered these to the axle and gear. So far so good. I managed to retain the rivets holding the geabox together. Will test it in one of my next loco builds using hornblocks so its removable. Pics later.

 

If i can do it.........

 

Ian

 

Edited November 17, 2022 by ianLMS

[ianLMS]

To expand a little on how i did it......

 

First, choose the right motor. This is a 12v dc dual shaft D model, 16000 rpm from ebay. About £7.80 plus postage i think. 

 

Leave motor on gearbox. Undo only one of the side screw on the gear box (1st pic above).

 

Using a large drill bit, gently ream out enough of the rivet tops so u can ease the side off. Take it slowly as the other shafts are pushed into the side holes and you dont want to displace these. 

 

Remove main drive shaft and gear. Leave all other gears and shafts in place.

 

Tap out the drive shaft gently, supporting just the gear. I used a hollow socket and tapped the shaft out with a pin hammer. The middle of the shaft is ribbed so the gear slots in and doesn't rotate, but the shaft will come out without issue.

 

Ream out the gear slightly to remove the tip of the ribs so its a tight fit on your chosen axle. 1/8" in my case. Slide on gear onto new axle. 

 

Slide on brass bearing with thin end facing the gear. Add other bearing on the other side of the gear and make sure the drive gear lines up with the other gears and it fits with only the slightest side play before soldering the bearings to the gear and shaft.

 

You may need to ream out the axle hole in side of gearbox to take new axle. A little at a time and test for a nice loose, but not sloppy fit. Relocate axle and gear into gearbox making sure everything lines up.

 

Add side back on, lining up the other shafts in the holes. Tap side over rivets and fit back the screw. If you removed too much rivet, a little solder or superglue with fix it. 

 

Test and make sure all works.

 

Either build chassis around gearbox, or use hornblocks. 

 

Hope this explains it. 

 

Ian

 

 

Edited November 18, 2022 by ianLMS

[tomparryharry]

On 18/11/2022 at 17:12, ianLMS said:

To expand a little on how i did it......

 

First, choose the right motor. This is a 12v dc dual shaft D model, 16000 rpm from ebay. About £7.80 plus postage i think. 

 

Leave motor on gearbox. Undo only one of the side screw on the gear box (1st pic above).

 

Using a large drill bit, gently ream out enough of the rivet tops so u can ease the side off. Take it slowly as the other shafts are pushed into the side holes and you dont want to displace these. 

 

Remove main drive shaft and gear. Leave all other gears and shafts in place.

 

Tap out the drive shaft gently, supporting just the gear. I used a hollow socket and tapped the shaft out with a pin hammer. The middle of the shaft is ribbed so the gear slots in and doesn't rotate, but the shaft will come out without issue.

 

Ream out the gear slightly to remove the tip of the ribs so its a tight fit on your chosen axle. 1/8" in my case. Slide on gear onto new axle. 

 

Slide on brass bearing with thin end facing the gear. Add other bearing on the other side of the gear and make sure the drive gear lines up with the other gears and it fits with only the slightest side play before soldering the bearings to the gear and shaft.

 

You may need to ream out the axle hole in side of gearbox to take new axle. A little at a time and test for a nice loose, but not sloppy fit. Relocate axle and gear into gearbox making sure everything lines up.

 

Add side back on, lining up the other shafts in the holes. Tap side over rivets and fit back the screw. If you removed too much rivet, a little solder or superglue with fix it. 

 

Test and make sure all works.

 

Either build chassis around gearbox, or use hornblocks. 

 

Hope this explains it. 

 

Ian

 

 

Hello Folks, Sorry I've been away...

 

Ian LMS: Yes, spot on. The rivet holes accept a small set-screw which can pass through the frame, from one side to the other.  If you use a countersunk setscrew, you can tap the one side to keep the motors on station, and you don't need a torsion bar, as those 2 screws  takes care of it. 

 

I'd suggest going for 'size' at least as axle diameter. Measure the axle first. If it's 3mm, use a reamer that size, or 1/8",  if it's imperial. If you've got doubts, try the hole with a ground HSS drill bit, but not a Chinese version. Pay the slight extra cost, and get it right. That  Micrometer is just there....

 

I'm very interested in how everyone has got on thus far. I've had to box up everything, and my memory is a bit dim. I do remember I've got an Aberdare or two somewhere, and if these work, there's a couple of 1701 panniers in the distance.

 

Many thanks,

Ian.