Ultra low cost home made drive system

Melbournesparks

Registered
30 Sep 2015
250
398
City of Eltham
The high cost and limited availability of motor blocks in G scale is often a major barrier to scratchbuilding. Initially my trams were powered by the original Bachmann tram motor blocks, but as many people can attest they're not fantastic runners. I really needed a new drive mechanism that was a: cheap, b: ran well and c: could be made without any cutting or drilling to close tolerances. In the end a wheel and traction motor assembly just like a real one was the easiest to construct, and only costs a few dollars each.

IMG_7856small_zpswxg80trq.jpg


Here is the prototype. The only 'construction' required is to solder a bit of brass tube to the outside of the motor case to hold the axle, so it is very quick and easy to build with no parts that have to be made accurately. It can be fitted to any 3mm axle, 31mm wheelset like used on most G scale rollingstock.

IMG_7858small_zpscnc2ekxc.jpg


A set of nylon gears like this from China has enough of the right size to make one traction motor assembly, so order as many as you want powered axles.

IMG_7859small_zpsdmbgtbcg.jpg


It includes a small pinion gear for the motor, and a large spur gear with a 3mm hole to fit on the axle. Fortunately it is just the right size that when the axle is fitted into the tube on the motor case they mesh perfectly. The assembled unit could probably fit into just about any bogie, all it needs to mount it is something to hold the other side of the motor to stop it rotating.

I made a pair of traction motor and wheelset units like this for the Ballarat tram, to replace the original Bachmann motor block.

IMG_7823small_zpsy1fdz23u.jpg


Both motors are wired permanently in series to give a realistic speed on 12v.


IMG_7853small_zps1aem8dfc.jpg


New 21E truck fitted in place.

Two motors is probably overkill for a tram, it will certainly pull three or four pieces of heavy rail bogie rollingstock.

Aside from a wheelset to mount it on, the only parts you need is a motor like this one:

http://www.ebay.com.au/itm/391219206218?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT

A set of gears like this:

http://www.ebay.com.au/itm/221988476709?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT

And a piece of 3mm inside diameter brass tube. Cost per unit is about 10 Australian dollars, not including the wheelset.
 
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Graham

In Smoggy Land
10 Mar 2016
380
277
72
Middlesbrough, England
This is really neat and may be a solution to something I also want to fix :cool: I take it that you also have pick-up's on the wheels?
 

Rhinochugger

Retired Oik
27 Oct 2009
30,264
3,632
North West Norfolk
I like it - I wonder whether, to drag more powerful loads, the motor might need a bit more anchoring, but once it's in place in the power truck, there could be some simple and crude fixes to support the motor and take the strain off the solder joint :clap::clap::clap::clap:
 
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Zerogee

Clencher's Bogleman
25 Oct 2009
17,125
1,690
North Essex
This is really neat and may be a solution to something I also want to fix :cool: I take it that you also have pick-up's on the wheels?

I think this is intended for battery power, so no pickups are required. If you wanted track power, I'm sure you could fit one of the LGB pickup mechanisms (the stand-alone ones they make for coach lighting pickups) on the opposite side of the axle from the motor, spaced so that the carbon bullets run near the edge of the wheel backs so as not to foul the big gearwheel.....

Jon.
 

Graham

In Smoggy Land
10 Mar 2016
380
277
72
Middlesbrough, England
Hi Jon

If you look at the picture you will see what appear to be carbon pick-ups on one side of both wheel sets which appear to be fixed to the brass cross pieces. I assuming the set up is a +ve OH pick up from the catenary as it is a tram and a -ve return to the track via the wheels :mm:

Yes for what I have in mind the I was thinking of using the wheel sets you mention and just one motor set to perhaps try to resurrect an otherwise irreparable Bachmann hand car :party:
 

Zerogee

Clencher's Bogleman
25 Oct 2009
17,125
1,690
North Essex
Hi Jon

If you look at the picture you will see what appear to be carbon pick-ups on one side of both wheel sets which appear to be fixed to the brass cross pieces. I assuming the set up is a +ve OH pick up from the catenary as it is a tram and a -ve return to the track via the wheels :mm:

Yes for what I have in mind the I was thinking of using the wheel sets you mention and just one motor set to perhaps try to resurrect an otherwise irreparable Bachmann hand car :party:

Yes, you're quite right, Graham - I had only been looking at the photos of the separate motor/axle units, not the one of the assembled chassis! That, and the later mention of running on 12 volts, had led me to assume battery power....

Jon.
 

Melbournesparks

Registered
30 Sep 2015
250
398
City of Eltham
I like it - I wonder whether, to drag more powerful loads, the motor might need a bit more anchoring, but once it's in place in the power truck, there could be some simple and crude fixes to support the motor and take the strain off the solder joint :clap::clap::clap::clap:

In 1:1 scale this is referred to as an axle hung traction motor, where one side of the motor is supported by the axle, and the other side is attached to the bogie frame; usually by a resilient mounting of some kind. I just used a simple loop of wire soldered to the motor case that fits over part of the frame. A large area solder joint like between the motor and the axle holder is very strong, the motor can't produce anywhere near enough torque to break it. Even if you scaled this design up to a large locomotive with four (or six) powered axles, each unit only carries the loads and torque forces from one axle.

I think this is intended for battery power, so no pickups are required. If you wanted track power, I'm sure you could fit one of the LGB pickup mechanisms (the stand-alone ones they make for coach lighting pickups) on the opposite side of the axle from the motor, spaced so that the carbon bullets run near the edge of the wheel backs so as not to foul the big gearwheel.....

Jon.

That's pretty much what I did, this overhead photo shows it a bit better:

Cr4s1FR.jpg


Graham is quite right, it runs from overhead power with both rails used for return current so pickups from both wheels are not insulated from each other. Another feature that's a bit hard to see in the photos is the guard made from a bit of brass channel that covers the bottom of the gears. Because they are quite close to the ground they need to be protected from picking up dirt and grass and other debries.
 
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Graham

In Smoggy Land
10 Mar 2016
380
277
72
Middlesbrough, England
Many years ago I worked in a motor repair shop in a large steelworks and one of our jobs was to overhaul the hung DC traction motors that were used in the big shunting units :)

I have looked for the small electric motors and the ebay supplier listed won't post to the UK:devil: I have however found the near identical motor from a different supplier (but the same manufacturer!!!) however the overall length including the shaft is a bit longer than the space between the inside of a wheel set so it looks like I would have to shorten the shaft ;) so a cunning plan is going to be hatched :giggle:
 

Melbournesparks

Registered
30 Sep 2015
250
398
City of Eltham
Many years ago I worked in a motor repair shop in a large steelworks and one of our jobs was to overhaul the hung DC traction motors that were used in the big shunting units :)

I have looked for the small electric motors and the ebay supplier listed won't post to the UK:devil: I have however found the near identical motor from a different supplier (but the same manufacturer!!!) however the overall length including the shaft is a bit longer than the space between the inside of a wheel set so it looks like I would have to shorten the shaft ;) so a cunning plan is going to be hatched :giggle:

Those were the days, the steelworks had their own motor shop!

I had to grind the shafts down on mine as well. They all seem to come with a 10-12mm shaft, but you need to shorten it to about 4mm. The critical dimensions are a length of less than 35mm minus the shaft, and a speed of about 5000rpm at 12v. You can get 12000rpm motors of a similar size, but I suspect they wouldn't have enough torque for that gear ratio.
 

Graham

In Smoggy Land
10 Mar 2016
380
277
72
Middlesbrough, England
Parts ordered so another project for the roundtoit list. Mind the gears are coming from Auz via sea mail:confused:
 

KeithT

Hillwalking, chickens and - err - garden railways.
24 Oct 2009
13,080
182
Nr Manchester
Many years ago I worked in a motor repair shop in a large steelworks and one of our jobs was to overhaul the hung DC traction motors that were used in the big shunting units :)

I have looked for the small electric motors and the ebay supplier listed won't post to the UK:devil: I have however found the near identical motor from a different supplier (but the same manufacturer!!!) however the overall length including the shaft is a bit longer than the space between the inside of a wheel set so it looks like I would have to shorten the shaft ;) so a cunning plan is going to be hatched :giggle:

Graham. Did you ask the ebay supplier if he would post to the UK? Twice I have found something I wanted with the 'Do not post to UK" restriction but in both instances the suppliers were only too willing to do it.
I suspect that they had not correctly set up or understood the 'small print' when setting up their accounts.
 

Graham

In Smoggy Land
10 Mar 2016
380
277
72
Middlesbrough, England

DafyddElvy

Registered
10 Feb 2021
99
9
West Lothian
The high cost and limited availability of motor blocks in G scale is often a major barrier to scratchbuilding. Initially my trams were powered by the original Bachmann tram motor blocks, but as many people can attest they're not fantastic runners. I really needed a new drive mechanism that was a: cheap, b: ran well and c: could be made without any cutting or drilling to close tolerances. In the end a wheel and traction motor assembly just like a real one was the easiest to construct, and only costs a few dollars each.

IMG_7856small_zpswxg80trq.jpg


Here is the prototype. The only 'construction' required is to solder a bit of brass tube to the outside of the motor case to hold the axle, so it is very quick and easy to build with no parts that have to be made accurately. It can be fitted to any 3mm axle, 31mm wheelset like used on most G scale rollingstock.

IMG_7858small_zpscnc2ekxc.jpg


A set of nylon gears like this from China has enough of the right size to make one traction motor assembly, so order as many as you want powered axles.

IMG_7859small_zpsdmbgtbcg.jpg


It includes a small pinion gear for the motor, and a large spur gear with a 3mm hole to fit on the axle. Fortunately it is just the right size that when the axle is fitted into the tube on the motor case they mesh perfectly. The assembled unit could probably fit into just about any bogie, all it needs to mount it is something to hold the other side of the motor to stop it rotating.

I made a pair of traction motor and wheelset units like this for the Ballarat tram, to replace the original Bachmann motor block.

IMG_7823small_zpsy1fdz23u.jpg


Both motors are wired permanently in series to give a realistic speed on 12v.


IMG_7853small_zps1aem8dfc.jpg


New 21E truck fitted in place.

Two motors is probably overkill for a tram, it will certainly pull three or four pieces of heavy rail bogie rollingstock.

Aside from a wheelset to mount it on, the only parts you need is a motor like this one:

http://www.ebay.com.au/itm/391219206218?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT

A set of gears like this:

http://www.ebay.com.au/itm/221988476709?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT

And a piece of 3mm inside diameter brass tube. Cost per unit is about 10 Australian dollars, not including the wheelset.
I appreciate it's been a while, but I don't suppose you still have the description for the parts you obtained, I ask because the ebay links don't seem to work for me, thanks?

David
 

Melbournesparks

Registered
30 Sep 2015
250
398
City of Eltham
I appreciate it's been a while, but I don't suppose you still have the description for the parts you obtained, I ask because the ebay links don't seem to work for me, thanks?

David

Yeah those links are long dead. Here's a more recent one for the motor.

The main attributes are a length of less than 35mm and about 5000rpm operating speed. There are many, many very similar motors out there which would probably all work just as well.

For the gears I think I just used a set like this one.

From memory the motor pinion has about 8 teeth and the axle spur gear about 45, but I can't remember for sure. I was worried the nylon gears wouldn't last very long in this application, but the original gears are still in use 5 years later running on some pretty steep gradients, so they've been surprisingly durable.
 

-bbbb

Registered
21 Dec 2017
437
112
Idaho
How have those cheap motors held up over the last few years?
 

DafyddElvy

Registered
10 Feb 2021
99
9
West Lothian
Thank you for the updated links, much appreciated.
Am I right in assuming you use track a wire to power the trams?
Assuming I'm correct how do you keep the track and wire clean?

Sorry for all the questions but I'm just starting out in this scale so I am on an information hunt, thanks.

David
 

Melbournesparks

Registered
30 Sep 2015
250
398
City of Eltham
How have those cheap motors held up over the last few years?

They've been very reliable which is good. It should be noted that these aren't the low voltage (1.5-3v) motors that are a similar size but have a plastic back, they're heavier duty with proper carbon brushes and bearing sleeves both ends.


Thank you for the updated links, much appreciated.
Am I right in assuming you use track a wire to power the trams?
Assuming I'm correct how do you keep the track and wire clean?

Sorry for all the questions but I'm just starting out in this scale so I am on an information hunt, thanks.

David

I'll post a reply to this over at the Eltham South Electric Tramway thread, there's a bit more context and pictures there.