Hot Mashima 1420

[Penrhos1920]

I have 2 locos with 1420s and both tend to run hot and after 30 minutes or so start slowing down. Is this a common fault in the 1420 or have I been unlucky? One motor is in a Highlevel pannier chassis and the other has replaced the motor of a Bachmann 56xx tank.

[34theletterbetweenB&D]

Not been that small. The Mashima 1430 in Bach's A1 (between their original faulty motor, and the subsequent Kader motor on later A1s) gets warmer than I really like after about 10 minutes running flat out on a heavy train: admittedly the loco is weighted to 550g. Doesn't get hot enough to start binding, though I have seen this happen on a 1426 which a friend has in a whitemetal MN. I was quite impressed that once cooled down the motor appeared to have taken no ill effect from its' thermal excursion.

[mikeg]

Similar to 34C I've got a 1426 in a small O gauge tank and this started to run hot when first installed, I found that the mesh was abit tight and the friction was causing the motor to work hard, once loosened off the problem did not happen unless I tried to pull a train that was to heavy for the loco to easily haul, ie more than the prototype would have been able to pull, but as I wanted the motor in the chasis and not above the running plate the size was all that would fit, so now its limited to 4 wagons and a brake or two coaches and works OK.

 

regards

 

mike g

[craigwelsh]

Do they run hot out of a loco? Possibly try running them unloaded for a while and check its nothing internal.

 

I've used the bigger 1426 without issue. Btw why have you got a 1420 on a High Level chassis instead of one of the bigger motors? I think it may have been the 1420 that Chris at High Level said wasn't amazing and you should aim for a larger one. Haven't built my Pannier chassis yet but I think i've got a 1426/28 for it.

 

Wish I could fit 16 series though, the one for the 14xx is superb, still haven't finished the sanding pipes and pickups on that though .

[hollywoodfoundry]

The 1420 you refer to is called a 1620 by Mr. Mashima, so being as he makes them, I will use his part number. These motors are a bit too small for most applications. The 1626 size is the pick of the 16 series range, as it develops 50%more power and 55% more torque than the 1620.

 

I have found examples of the 1620 that new, out of the box, were weak and did not develop full power. As a result, I discourage anyone from choosing them unless for very light duty.

 

A further problem is that these motors use Neodymium magnets, and if you allow them to get too hot, the magnets lose strength and the motor will become near to useless.

 

Geoff

[Miss Prism]

I've got a round can 1620 and that runs quite hot, although it does have a hefty flywheel on it, which probably exacerbates the problem.

[naugytrax]

That's an interesting suggestion. My first thought would have been that the extra surface area of the flywheel (which is thermally connected to the motor shaft) would have helped the motor to dump heat to the atmosphere, thus keeping it cooler! Does this have something to do with extra load on the motor bearing at the flywheel end, causing greater frictional losses there?

[JeremyC]

I've a similar problem to Penros1920 with a Mashima 1626 round can I've installed in an A2/1 pacific I'm building, which gets very hot and loses power after about 20 minutes running. The design of the loco kit is such that I might be able to go to a 1628, but no larger.

 

As someone who's built loco kits on and off for 35 years I would say while the modern motors are quieter, smoother and draw less current, for 4mm I've yet to discover a motor more rugged and able to take abuse than the now ancient X04 and its derivatives.

 

Jeremy

[Miss Prism]

That's an interesting suggestion. My first thought would have been that the extra surface area of the flywheel (which is thermally connected to the motor shaft) would have helped the motor to dump heat to the atmosphere, thus keeping it cooler! Does this have something to do with extra load on the motor bearing at the flywheel end, causing greater frictional losses there?

The extra cooling area notion is interesting, but it doesn't work that way. Whilst some heat of course conducts through the 2mm shaft, I think it is the load demand in accelerating the flywheel, a rather monstrous 18mm (dia) x 12mm in my case, as well as the transmission load on top of that, which results in the motor body heat. All motors are nothing more than heat transfer machines, and I think some of the older Mashimas run naturally hot anyway under significant load. (Heat buildup is very rapid in electric motors.) A well-balanced flywheel shouldn't put too much stress on the bearings themselves, provided they are properly aligned in the first place.

 

One of the reasons why X04s are so rugged is their excellent cooling system, but not all open framers are so blessed - the Romford Terrier ran furiously hot for example.

[Penrhos1920]

Do they run hot out of a loco? Possibly try running them unloaded for a while and check its nothing internal.

 

I've used the bigger 1426 without issue. Btw why have you got a 1420 on a High Level chassis instead of one of the bigger motors? I think it may have been the 1420 that Chris at High Level said wasn't amazing and you should aim for a larger one. Haven't built my Pannier chassis yet but I think i've got a 1426/28 for it.

 

Wish I could fit 16 series though, the one for the 14xx is superb, still haven't finished the sanding pipes and pickups on that though .

 

I should have said it was out of the body running on a rolling road.

I think it was the motor that Chris recommended for the pannier chassis at the time.

 

The good news is that after a lot of running in, it now runs a lot cooler and for a lot longer, so by the time the track has been laid it should be able to haul the train its destined for (an eight coach double header with another pannier or saddle tank).

 

Given several me too's, including other Mashima motors. What motor should I plan for the next loco? A Rhymney 0-6-2T that has got to pull 20+ empites up 1 in 40?

 

Thanks

[Miss Prism]

What motor should I plan for the next loco? A Rhymney 0-6-2T that has got to pull 20+ empites up 1 in 40?

Let's say a 4-wheel wagon weighs 50g and has a rolling resistance of 1g. So you will need (20 x 1) + (20 x 50/40) = 45g extra tractive effort from the loco to haul a 20-wagon train up the grade. The loco, of weight x, will also need to haul itself up, with an extra x/40, so if say x is 300g, that will be 7.5. 45 plus 7.5 is 52.5. With decent suspension and non-greasy wheels, you should be able to get 52.5g traction if your weight over drivers is 52.5 x 5 = 260g, or maybe best case 52.5 x 4 = 210g. You shouldn't have much problem in a big 0-6-2T getting a balanced 260g over the drivers provided you don't waste that real estate on gears or motor. Your train speed requirement is very low, and even with high-ratio gears (80:1?), you will still want a low-revving motor, which means a big motor of course, like a 1626 or maybe an 1824, because you need to develop good power at the low end. And there's your conundrum - I suspect you might have to sacrifice cab floor space to get the motor in there, especially if the number of empties becomes '20+'.

[Penrhos1920]

Let's say a 4-wheel wagon weighs 50g and has a rolling resistance of 1g. So you will need (20 x 1) + (20 x 50/40) = 45g extra tractive effort from the loco to haul a 20-wagon train up the grade. The loco, of weight x, will also need to haul itself up, with an extra x/40, so if say x is 300g, that will be 7.5. 45 plus 7.5 is 52.5. With decent suspension and non-greasy wheels, you should be able to get 52.5g traction if your weight over drivers is 52.5 x 5 = 260g, or maybe best case 52.5 x 4 = 210g. You shouldn't have much problem in a big 0-6-2T getting a balanced 260g over the drivers provided you don't waste that real estate on gears or motor. Your train speed requirement is very low, and even with high-ratio gears (80:1?), you will still want a low-revving motor, which means a big motor of course, like a 1626 or maybe an 1824, because you need to develop good power at the low end. And there's your conundrum - I suspect you might have to sacrifice cab floor space to get the motor in there, especially if the number of empties becomes '20+'.

Thanks, I'm not sure that I follow your maths. Are you saying that a loco's tractive effort is 1/5 to 1/4 of its weight? Didn't the Scalefour society used to have a competition that measured tractive effort?

 

Any way I've worked out that I can get a 1824 motor in if I used a HighLevel RoadRunner+ 54:1 gearbox. Using data provided by HollyWoodFoundry here http://www.rmweb.co....-for-your-model I've calculated that this combination should give me 21 mph - almost spot on. Even better news is that the kit weighs in at about 300g.

 

[bertiedog]

My choice, no maths, but 40 years experience building!!....60:1 would give scale max, but for practicality 50:1 might be better, so the chosen one, 54:1 would well suit. Feedback Controllers and DCC make low speed better these days.

 

If it is intended to run at scale 21 mph on a large layout, then lower the ratio to slow the motor down, and ease gear wear, but if a small layout, and little running then raise the ratio.....don't forget a high ratio will always increase noise somewhat, and the wear and tear on the gears.

 

50 and 60 to one can turn a good model into a coffee grinder even at scale speed! the art is not the maths but a judgement as to how low you can go?, not how high........

 

I have just completed a diesel with 15:1 gears, it takes about a minute to do a foot, very satisfactory indeed, but it's seven pole, with a flywheel, and on feedback control. If I were designing it myself I would double the ratio, but it's a sixty year old vintage unit, a Lindsay, I do not want to alter it.

 

Stephen.

[bertiedog]

I think the old rule of thumb for haulage was 1/6th the weight of a loco with all driven wheels with steel tyres on steel track, but I own a test track with nickel, brass, and steel track, with pulley gauges for testing wheels etc, done for some NMRA friends research.

 

Haulage varies all over the place!! efficiency alters with bearings etc, traction with springing, and plain weight.

 

The best I could was a GWR 282, with springing, all ball raced, split chassis, no pickups at all, home produced 7 pole motor with ball raced flywheel, solid brass construction milled out, weighs in at 3 lbs, quite impossible to stall with 200 plus boxcars behind it at an NMRA meet!!

 

You can get specific tractive effort figures, but it depends on the bearings of the stock, in the case of the boxcars they were on Delrin trucks.

 

Ohh.... and the best tractive aid.....magnadhesion!!! on steel track of course. I tried it with Gibson's in P4 on steel, it works fantastically well!!! Neodymium magnets make it work well, and are invisible inside the frames.

 

Stephen.

[Miss Prism]

Are you saying that a loco's tractive effort is 1/5 to 1/4 of its weight?

It can be, with good balanced suspension and very clean wheels, but I wouldn't disagree with Stephen's 1/6th as a more likely pragmatic rule of thumb. Prototype haulages on greasy wet rails could be down to 10% or less. I remember Andy Y did some tests (on a Bachmann 9F?) way back in a previous RMweb, and got something like 11%, but that was of course a rigid chassis.

 

Didn't the Scalefour society used to have a competition that measured tractive effort?

Amongst other running qualities, yes. Originally it had a pulley and weights, which was later replaced by a strain gauge, but I'm not sure it's output and calibration could be relied on!

[bertiedog]

It can be, with good balanced suspension and very clean wheels, but I wouldn't disagree with Stephen's 1/6th as a more likely pragmatic rule of thumb. Prototype haulages on greasy wet rails could be down to 10% or less. I remember Andy Y did some tests (on a Bachmann 9F?) way back in a previous RMweb, and got something like 11%, but that was of course a rigid chassis.

 

 

Amongst other running qualities, yes. Originally it had a pulley and weights, which was later replaced by a strain gauge, but I'm not sure it's output and calibration could be relied on!

 

Weights and pulleys work best, the set I have are ex lab BS grade weights, with the wire multi strand S/Steel running over ballraced nylon pulleys, tested with a lab grade strain gauge between the wire and the drawbar to test calibration.

 

I was reading a site about the Pennsylvanian Duplex T locomotives, that could break traction at 90 mph+ near destroying the poppet valve gear as the unit that broke traction revved up disastrously. The boiler was not even stressed by the demand, and tales of them getting to 120mph quite likely.

 

At the other extreme a Japanese model engineer used to delight in driving himself behind an O gauge 060, which weighed about 3kgs, he was seven stone, simply against all theory.

 

1/6 was from my tests, 1/5 is often taken by Model Engineers on steel track, and 1/7th on aluminium track, common with passenger hauling.

 

Stephen.