Replacing Mashima motors

[Pebbles]

Motors! motors! motors!.  Over a period of time, via ebay, I have purchased motors that I identify as common to various Hornby engines. Indeed that which resides in the J15 was on sale at  Scalefour Stores a couple of years ago. These and other Hornby? motors - I think the 8F type and the A/1/3/4 type, when they were available, cost less than £2.00 - are generally quoted as 12 to 24 volt. As has been previously outlined, the very cheap end of the market tend to come from applications where there is an intermittent power requirement. There is little reason why the cheaper motors cannot find applications but if you are looking for prolonged running at maximum power they may not be what you are looking for. As the geared motors are offered with a band of ratings when buying always look for the identification numbers on motors as these can give an indication as to what you are buying. Whilst off key, we are now provided with motors that cannot be serviced and when the brushes give out are expected to be thrown away- bring back the X04.  

[Izzy]

I recently visited a local show where one stand had various flavours of these small motor/spur gearbox combos (N20's?) for sale. These were being sold as suitable for scenic use, powering windmills etc that kind of use, and not as powerplants for locos. The stated voltage seemed to be allied to the gear reduction. I can't remember the actual details but broadly they were 3v, 6v, and 12v, with the later having the highest reduction - 300rpm IIRC - and the lower voltages rather less, 100rpm and 50rpm I think. The actual motors looked identical, as you might expect, so getting those of the right voltage might be something of a lottery if there isn't clear indication of their actual specs, and especially if they come sans gearbox. Similar sized motors are used in smaller servos, will of course be 6v rated, and could well be what is often available on e-bay when sold motor only.

 

A word of warning if I may. Having tested the 6v servo motors one fact that stands out is the high current they draw, running both off and on load, compared to the more normal motor usually used with model locos. Anything around 100mA light, and 900mA under stall. This may be one reason among many why some are frying themselves, and especially if they are 3v ones.

 

By comparison, a Mashima 1833 I recently transplanted into a Bachmann 08 ( the original motor died for no apparent reason and I had the 1833 spare (they are almost the same size), couldn't be persuded to draw more than 0.5 amp stalled at any voltage up to 12v ( I wanted to ensure the decoder used could cope with the Mashima current draw given I kept reading they were higher than other motors).

 

Izzy

[johnarcher]

It runs no differently to the equivalent Mashima, which I have in other similar small industrial locos. I can't say how well it works under continuous running as, apart from half an hour on rollers to test, it only runs up and down a 4ft. plank and being in a small shunting loco I doubt if it is ever run at full voltage. But then small shunting locos are really the only types that these motors will be used for anyway and if you run them at near to realistic speeds they're never going to get 12 volts. I can only imagine that the poster who had one overheat within a minute and under no load simply had a duff one.

 

Apart from sticking two wires to them to see if they work at all, I haven't tested the N-Drive lookalikes, that I bought for a couple of quid each but I will fix one to a spare gearbox and see how well it runs under different voltages.

Thank you, like you I'm never likely to use it at anywhere near 12 volts (the Shropshire and Montgomery didn't go that fast), or for long continuously.So one of them, I think, has achance of being OK. I have an N Drive 1015 and an N20 of the non-gearhead variety, I'll do a bit more experimenting.

 

PS edit - actually the non-N Drive one is on eBay as an N30, is that just an N20 without the gears or different?. I hope it works out, it's a useful 1020ish sort of motor. The various advertisers seem a bit vague as to voltage rating, 6 or 12 volts. I wondered whether to protect it with one of the resistors Nigel Lawton sells to go with his 6v micro motor? (Electronics isn't (aren't)?) my strong point I fear. I must try and think of something that is).

Edited April 30, 2018 by johnarcher

[micklner]

As mentioned before the N Drive Motor is now fitted to a 4mm 2-4-2 chassis and running very well and quiet.

 

One more of the N20 motors also arrived today from a different Chinese supplier, exactly the same of the other two also mentioned earlier , held in fingers, zero load and  too hot to hold any longer after about a minute on 12 volts, one more to arrive at some point from China I doubt very much if it will be any better.

[Pebbles]

Just received motors - six pole armature 10mm x 10mm square about 15/16mm long with 1mm shaft. Supposedly rated at 7.2/9 volts, but even at this voltage displays very good torque at reasonable revs. I think something place inline to limit the voltage would be useful.

[johnarcher]

Just received motors - six pole armature 10mm x 10mm square about 15/16mm long with 1mm shaft. Supposedly rated at 7.2/9 volts, but even at this voltage displays very good torque at reasonable revs. I think something place inline to limit the voltage would be useful.

What motor is that? There have been so many mentioned that I'm losing track/

[Jol Wilkinson]

What motor is that? There have been so many mentioned that I'm losing track/

 

It could be this one.

 

https://www.ebay.co.uk/itm/Minebea-Square-Motor-DC-6V-9V-7-2V-14700RPM-10-10mm-6-pole-Rotor-Large-Torque-/282607882699

 

Note that the information states that "easy heating @9v, cannot work long time".

[Pebbles]

It could be this one.

 

https://www.ebay.co.uk/itm/Minebea-Square-Motor-DC-6V-9V-7-2V-14700RPM-10-10mm-6-pole-Rotor-Large-Torque-/282607882699

 

Note that the information states that "easy heating @9v, cannot work long time".

 

That's it, or similar. It would appear that at the reduced voltage it's at least as powerful as some of the other motors mentioned.

[doilum]

A few years ago, a relative donated a chair with a vibrating massage facility ( pause for cheap laughter) to see if it would help my ailing back. Big and tatty, it quickly fell out of favour and was disassembled to make its final journey to the tip. Mechanical curiosity led me to salvaging half a dozen 1833 type motors fitted with asymmetric flywheels. One of these found its way into Antwerp, one of my almost scratch built austerities ( the bunker was a left over from a Mercian kit).

This produced a loco with quite a low top speed, not really a problem, but sadly lacking in "grunt" compared to the rest of the stable.

Around the same time, I bought another pair of 1833 types from a trader in Wales. These proved to be just about the equal of the Mashima motors and, at the time, very good value at £16.

Since then I have pretty much standardized on the Canon 1833.

[johnarcher]

Thanks Jol and Pebbles, I'll give those a try - 6 poles looks more promising than 3 I think?

Probably the low voltage and heating wouldn't be a problem where nothing moves above a scale 25mph or so, still a resistor to protect it might be a good idea, such as the Lawton one I mentioned. Could someone with more electrical knowledge confirm that?

 

Incidentally Nigel Lawton also does this

http://www.nigellawton009.com/MiniMotors.html (as well as the 6V one he uses the resistor for).

The only thing that puts me off is that it is coreless and so presumably can't use a normal worm gearbox. Maybe an enclosed box and neoprene tube coupling?

Edited May 2, 2018 by johnarcher

[Pebbles]

The problem with a simple resistor appears to be that it would - to use a non technical explanation - remove the first 3 volts. That is 3 volts would be needed before the motor received any power. To preserve a degree of compatibility with other motors ideally the 9v motor needs to be protected from the final 3 volts that is the range 9 volts to 12 volts. It would appear that DCC may offer that facility, but its not where I would want to go.  

[johnarcher]

The problem with a simple resistor appears to be that it would - to use a non technical explanation - remove the first 3 volts. That is 3 volts would be needed before the motor received any power. To preserve a degree of compatibility with other motors ideally the 9v motor needs to be protected from the final 3 volts that is the range 9 volts to 12 volts. It would appear that DCC may offer that facility, but its not where I would want to go.  

Me neither. Maybe it woud be enough that, with the very limited speed required, it would never receive more than 9 volts anyway? They're cheap enough to try anyway.

One could stick something on the controller dial so it can't be turned past about 3/4 power! (A suitably non-electronic possibility for me).

[5050]

One could stick something on the controller dial so it can't be turned past about 3/4 power! (A suitably non-electronic possibility for me).

You could always try will-power or even self-control?

[johnarcher]

You could always try will-power or even self-control?

I used all that up in giving up smoking some years ago.

Also at my stage of life will power is a weaker force than absence of mind I fear.

[Michael Edge]

The small 6 pole square motor does seem to get a bit warm but I don't think it will get too hot. There is a bigger square motor (about 15mm or so) which I haven't tried yet. it will go in a bigger loco on a High Level gearbox when I do.

[Pebbles]

Have obtained the larger 15mm square motors, they are a bit on the slow side - if I recall quoted at about 8500 rpm - but with high torque.  

[Nick Holliday]

The problem with a simple resistor appears to be that it would - to use a non technical explanation - remove the first 3 volts. That is 3 volts would be needed before the motor received any power. To preserve a degree of compatibility with other motors ideally the 9v motor needs to be protected from the final 3 volts that is the range 9 volts to 12 volts. It would appear that DCC may offer that facility, but its not where I would want to go.

 

I don't think simple resistors work this way. The voltage drop across a resistance is dependent upon the current passing. Ohm's Law voltage = resistance x current. Simplifying the situation, if, say, the motor draws half an amp at 9 volts, then the voltage across a six ohm resistor in series would be 3 v, so the overall voltage would be 12. When the supply voltage is lower, say 6 v, then the current will be reduced, although not necessarily linearly, as a motor has little resistance, its impedance being the current draw. If we assume for this exercise that the current draw is halved, then the voltage across the resistor would be similarly reduced to 1.5 v, so the motor is receiving 4.5 volts. There would be little difference in the starting voltage, assuming the resistance value has been correctly calculated.

[Jol Wilkinson]

The problem with a simple resistor appears to be that it would - to use a non technical explanation - remove the first 3 volts. That is 3 volts would be needed before the motor received any power. To preserve a degree of compatibility with other motors ideally the 9v motor needs to be protected from the final 3 volts that is the range 9 volts to 12 volts. It would appear that DCC may offer that facility, but its not where I would want to go.  

 

To get 7 volts at the motor with 12v input and 500mA (.5A) current draw needs a 10 Ohm resistor. 500mA is the quoted stall current at 7.2 volts. The voltage drop across 10 ohms will be less at lower current draw, which will happen at lower voltages. So at .1A the drop will be 1.0 volt, but the applied controller voltage will also be lower. So the suggestion that the first 3 volts are "removed" doesn't quite give the correct picture.

[Stanley Melrose]

 A link to the supplier perhaps?  Please!

 

Stan

 

Have obtained the larger 15mm square motors, they are a bit on the slow side - if I recall quoted at about 8500 rpm - but with high torque.  

[Stanley Melrose]

Answering my own question <https://www.ebay.co.uk/itm/2pcs-Minebea-Square-Motor-DC-12V-18V-6500RPM-10000RPM-Large-Torque-6-Pole-Rotor-/282303561073>

 

Stan

 

 A link to the supplier perhaps?  Please!

 

Stan

[Jol Wilkinson]

Answering my own question <https://www.ebay.co.uk/itm/2pcs-Minebea-Square-Motor-DC-12V-18V-6500RPM-10000RPM-Large-Torque-6-Pole-Rotor-/282303561073>

 

Stan

 

Stanley,

 

they look a bit more useable at 12v but the low speed might be a problem. The lowest ratio I could find with a quick look with 2mm bore worm and 1/8"are the Romford 20 series gears on the Markits (2013) price list with a 27:1 ratio. That would give just over 40 mph scale speed with 5' 6" wheel and just under 50mph with 6' 6" wheels. Ultrascale do a 30:1 set so slightly slower speeds.

 

That would be okay for smaller layouts, BLT's, etc. but wouldn't suit large layouts with Pacifics hauling main line expresses.

 

Jol

[Stanley Melrose]

Ah Jol,

 

Time to contemplate other forms of gearing than just a worm and cog.  Surely, one big advantage of a slow-running motor is that it is better suited to bevel/contrate and pinion gears to make the right-angle turn in the drive and then multi-stage spur gearing to complete the desired reduction because it will need one fewer reduction stage with advantages in lower friction, reduced gear whine and maybe even reversible drive.

 

We shall see once the motor(s) arrive from the Heavenly Kingdom.

 

Remember also that not everyone models the ECML . . .

 

Stan

PS Worms are for catching fish!

 

 

Stanley,

 

they look a bit more useable at 12v but the low speed might be a problem. The lowest ratio I could find with a quick look with 2mm bore worm and 1/8"are the Romford 20 series gears on the Markits (2013) price list with a 27:1 ratio. That would give just over 40 mph scale speed with 5' 6" wheel and just under 50mph with 6' 6" wheels. Ultrascale do a 30:1 set so slightly slower speeds.

 

That would be okay for smaller layouts, BLT's, etc. but wouldn't suit large layouts with Pacifics hauling main line expresses.

 

Jol

[Pebbles]

Stanley,

 

they look a bit more useable at 12v but the low speed might be a problem. The lowest ratio I could find with a quick look with 2mm bore worm and 1/8"are the Romford 20 series gears on the Markits (2013) price list with a 27:1 ratio. That would give just over 40 mph scale speed with 5' 6" wheel and just under 50mph with 6' 6" wheels. Ultrascale do a 30:1 set so slightly slower speeds.

 

That would be okay for smaller layouts, BLT's, etc. but wouldn't suit large layouts with Pacifics hauling main line expresses.

 

Jol

Old Hornby 13:1 gears; using a signal start worm 26:1, I've still got a few. Romford also did/do a 20:1. If the bore in either the worm or the gear is too large, the lathe does the rest.  Using the Markits 27:1 with motor at 8500 rpm - the figure quoted when I purchased mine  - gives a wheel rotational speed equal to 62mph with 5' 6'' wheels and 73mph for 6'6'' wheels. By the way Jol many thanks for the info on resistors.

[Jol Wilkinson]

Ah Jol,

 

Time to contemplate other forms of gearing than just a worm and cog.  Surely, one big advantage of a slow-running motor is that it is better suited to bevel/contrate and pinion gears to make the right-angle turn in the drive and then multi-stage spur gearing to complete the desired reduction because it will need one fewer reduction stage with advantages in lower friction, reduced gear whine and maybe even reversible drive.

 

We shall see once the motor(s) arrive from the Heavenly Kingdom.

 

Remember also that not everyone models the ECML . . .

 

Stan

PS Worms are for catching fish!

 

Stanley,

 

the difficulty with bevel or contrate gears is  that they need careful control of side play/end float for correct mesh. That is less critical with worm and worm gear, the shaft centres being the critical dimension and that has been easier to control with the types of motor mounts/gearbox designs we have become used to..

 

Overall width can also be a problem as the driven gear is offset to one side, whereas worm and gear are in line. I've looked at gearing over the years for various 4mm loco kit drive applications and always found that worm and gear, despite it's mechanical inefficiency, provided the most straightforward application. However, something along the lines of a High Level gearbox with a lower loss worm/gear first stage followed by  spur gears for a overall suitable gear ratio would seem a good solution.

 

North West Short Line provide a range of gears that might suit.

 

http://www.nwsl.com/nwsl-online-catalog.html

 

Ultrascale do plastic contrate gears but I haven't yet found a set of suitable size bevel gears that can be adapted to suit our usual motor shaft or axle sizes.

 

Jol

[whart57]

Geoff Helliwell (who has done a lot of work on this in 3mm scale) abandoned bevel gears because they were nigh impossible to mesh in small scale locos. He did however report that meshing crown and pinion gears was easier than meshing worm and wheel. He has also produced a kit (sold within the 3mm Society) for a motor bogie and for a drive for small tank locos (OK GW panniers). These will go down to 12mm gauge. I have taken one of his motor bogies and modified it for 9mm gauge by making it outside framed. The main issue for 3mm scale use is that the smallest available crown wheel is 8.5mm diameter which only just fits in a bogie using 9mm diameter wheels. However my limited experience is that crown and pinion is the easiest of the drive turning gear trains to set up as well as the one that puts least drag on the motor. I forget who it was, Iain Rice possibly, who said that putting a worm drive in a small scale loco is like driving with the hand brake on.