Kato 117 Series runs fine for 20mins, then starts stalling.

[Welshbloke]

As the title! I bought a tidy used example of a 10-419 Kato 117 Series six-car EMU recently, after some cleaning (and replacing a dead diode in one end coach) it'll run fine for about 15-20mins but then starts stuttering. The wheels and rails are clean, and if you stop it for a while it'll do the same again.

 

I suspect a motor problem, but the brushes, brush holders and commutator are clean. I pulled the brush holders out to clean everything, then reassembled after gently stretching the brush springs to improve contact. Also stripped the bogies down, cleaned the pickups, and rebuilt. It ran much better for the usual 15-20mins then started playing up again! Any ideas?

[kvp]

This sounds like the motor is overheating. You can feel if motor is hot after it starts to stutter. The cause could be high friction in the transmission (lack of lubrication or jamming/deformed parts) or damage in the motor windings. You can detect the first by trying to move the main shaft of the motor by hand, while the second one is measurable with a multimeter. The electrical resistance of each winding should be the same and roughly equal with another similar Kato set. You can measure this through the wheels (and selecting the commutator position by hand) or directly on the commutator when the car is disassembled.

 

I would check the lubrication first, then the free movement of the mechanical parts and finally the motor windings.

[HantuBlauLOL]

Slowing down or completely stopped?

[Welshbloke]

Bit of both - if you're running fast enough it'll stutter, slow a bit, then pick up again. If you run it slower it'll stop. It usually seems to happen just as the power car comes off the superelevated curves, which would fit with a tight spot in the gearing as the weight shifts.

 

I did give the motor a quick spin from a 9v battery after cleaning it out, and it seems to spin fairly freely. It is getting warm though. I'll try putting the bogies and the motor through my ultrasonic cleaner and see if that improves matters - do Kato use gears which don't need lubricating or is that just Tomix?

 

I did wonder about just replacing the motor, but the brushes have plenty of graphite left so I'd rather not junk it.

[HantuBlauLOL]

I'm thinking about the worm gears, are they clean?

 

I don't think its because of electrical pickup problem.. How about the bogies, have you cleaned them? Motor bearings? Cardans?

 

Actually if you connect a speaker into Tomix's CL controller output it will generates ultrasonic sound, lol.

Edited September 5, 2015 by HantuBlauLOL

[cteno4]

Does sound like a winding or lubrication issue. Happening at a particular point does point to lubrication/binding perhaps. But lowered power from a winding issue could cause it to stall where there is a bit for friction involved in certain positions that usually it can power thru.

 

Small cracks or a slim spot in the winding wire can cause increased resistance and heat.

 

I've heard folks using those little engine spot IR meters to watch motor heat. They can be had for $20 for cheap ones, been meaning to look into one myself.

 

I guess if you have a similar model that used the same motor you could try a swap to test. You seem very proficient in doing the full breakdowns!

 

Good luck and keep us posted!

 

Jeff

[kvp]

Winding issues can be detected by measuring the total resisance between the wheels. However the motor shaft has to be turned by hand so each commutator position is reached and measured. For comparision, it's possible to measure another (good) set in any position. If the motor has different values between each position or a greatly lower/higher overall value, then the motor has a problem. This test can be done without taking the good reference set apart.

[HantuBlauLOL]

But he already reassembled the motor and found nothing. I don't think its the motor which caused the problem

[Welshbloke]

I cleaned the pickups on the bogies (and the axle pinpoints which go into them), and bent the copper strips on the chassis down a bit to make firmer contact. Made no difference, but at least I know the electrical side is reliable now!

 

I'm definitely leaning towards motor, the metal chassis does get noticeably warm to the touch by the time it starts stuttering. The gears are pretty soaked in oil, which makes me wonder if it has pulled a load of dirt in and caused excess friction.

 

The only worry I have is whether I managed to do something irrepairable by pulling the brush holders out? I know they went back together correctly but I wasn't sure if the entire brass tube assembly is supposed to come out, or just the cap on the end of it?

 

If it comes to it, does anyone have a part number for a new motor? This is the first Kato model I've had to dismantle so I'm not sure how many different types they use.

 

I spent my childhood wrestling with Graham Farish N models, from the era when you were lucky if it ran at all and even luckier if it didn't split its axle gears. Kato are much easier to work on!

[HantuBlauLOL]

Motor warming is normal.. If the heat made it untouchable then its not.

[Welshbloke]

It's not that hot, just noticeably warm to the touch.

 

I unclipped the bogies and cleaned the gears (dribbled some washing up liquid in, twiddled the driveshaft with my fingers to spread it around, then rinsed them gently while still twiddling). That removed all the excess grease/oil, and the running did improve. It now gets to about the 30min mark before the stuttering begins!

 

I'm suspicious that the motor is essentially fried for whatever reason, having had similar problems with a Tomix loco before now which were only cured by a new motor. I'll take the motor out and check it again sometime. I am wondering if it's related to the brush springs not pressing hard enough - that would cause arcing and excess heat after all. I'll try stretching them before reassembly.

[HantuBlauLOL]

Have you ran the motor alone? Without the another mechs

[Welshbloke]

I did briefly, but not from a variable supply. Plan is to hook a couple of test leads up to the motor alone, turn the power right down, and watch for tight spots.

[Welshbloke]

An update, after I had another fiddle with it:

 

I noticed that the brush holders were loose, so pulled the motor apart again. The armature spins freely and silently with no brushes fitted, so it isn't the bearings.

 

This time I unclipped the end caps and refitted the brush holders to the motor with a smear of gel superglue, which should stop them wiggling about. I gave it a few minutes to harden then reassembled the motor, tested it on a 9v battery, then reassembled the power car and gave it a quick back and forth test on my B Train Shorty oval (it won't go around 117mm radius curves, so I can't do a proper test there).

 

I suspect that the loose brush holders were allowing the brushes to wobble around rather than being held square against the armature, that could easily cause arcing/flashovers and overheating. I'll set a larger oval up and give it a proper test run at some point, at the moment I'm just happy that I don't seem to have managed to get superglue into anything which is supposed to move!

[cteno4]

Superglue, second only to duct tape!

 

Glad you may have found the issue! I've never had that happen (worn and fragmented brushes though) so something to put on the checklist! Always good to get more data for the future.

 

Jeff

[Welshbloke]

I'm not sure if it's available elsewhere, but the stuff I used is a gel superglue with "powerflex". Basically it stays slightly rubbery after hardening, so it isn't as brittle as the usual cyanoacrylate.

 

Unit has now notched up almost an hour's running in each direction with no sign of stuttering, going to pop back and check it in a few minutes as it's currently circulating on a test oval on the kitchen table. Next job will be swapping the Rapidos for Tightlock couplers (on order), as the movement in the Rapido springs is noticeable over a six car train.

 

Now to see if the same problem is causing a Tomix 211 Series to produce intermittent screeching sounds, as its behaviour is very similar...

[cteno4]

Interesting I had not seen a CA glue here that had a rubberized additive, seen lots of gels to allow gaps and deal with porous surfaces also fillers to help bridge gaps on rougher surfaces. Baking soda is great for this in places you can get it there like a fillet joint.

 

They do sell it here as loctite super glue ultra control gel. The powerflex is not used and the package does not talk about flexability but impact resistance (goes to figure). Maybe it's something with product labeling here or just the way they market it. Going to have to pick some up and experiment!

 

I researching it I found they also had a 2 part system for CA glues and it appears to be treating one surface with naphtha based solvent and ca on the other for more rapid bonding. I guessing the chemistry is both cleaning the surface but perhaps reducing acidity for bonding. Moisture can do this (foggojng with your breath can work) some. Perhaps there is some water there so the solvent drys and leaves just a bit of moisture there. Only doing one surface then let's the glue not start polymerizing faster until the parts are joined.

 

I've usuall found the squealing to be crud and or lubricant related, but I suppose it could be loose brushes squealing! I have rarely run into motor issues, most of the time it's been drive chain related or pickup related, but I'm sure I will find some eventually. I do have a couple of shelved problem child's that I need to get to as the usual strip down, clean and lube did not repair!

 

Thanks,

 

Jeff

[Welshbloke]

Sadly it looks as though Tomix motors can't be repaired in the same way, as the brush holders don't have removable end caps. Those are essential as they mean you can avoid risking gluing the brushes solidly in place by removing them before you start, and also that you can leave the glue to set without the pressure from the brush springs trying to push the holders back out of the motor. Must be much easier in Japan where you can presumably go to your local shop and buy a complete new motor!

 

The packaging here describes the glue as "Ultra strong and flexible". I've never tried bending it, but it seems to cope with sharp knocks which would shatter normal superglue. I occasionally have to use it to hold the sideframes on B Train Shorty bogies if they're loose, or keep trying to pop back off as the tabs aren't quite in the right place.

[HantuBlauLOL]

Flexible superglue.. Hot glue eh?

[cteno4]

Yeah but hot glue does not grab well, especially to smoother surfaces and especially under conditions where things get warm! Also not very controllable. Love hot glue, but just not for this kind of situation. Use to use gobs of it dong exhibit mock ups all the way to 1:1 scale with chipboard and corrugated cardboard! It's fantastic for the fast tack then come back and do a fillet of it for some added strength. I want to get some of this to play with and see its properties!

 

I almost got myself shot one night using a hot glue gun! I was working very late one night on a big presentation project (mock up of a big 2d rock with graphics on it for an exhibit). One of the construction guys left a gate open and the main door to warehouse I was working in was left unlocked. Police saw the open gate and lights on so came in to investigate. I was luckily kneeling down in the middle of this big panel gluing in supports with a huge monster of a hot glue gun we had and I heard someone clear their throat. Luckily I didn't jump up as I was just holding a part to dry just then a few other folks worked late at night now and then. Looked over my shoulder and there was a head poking around the shop dust curtain and then he pulled the curtain back so I could see his uniform. I started explaining who I was while just leaving the glue gun on the floor and getting up very slowly with my hands visible! He said ok and then the curtain came all the way aside and his partner was behind the curtain putting his gun back in his holster! Don't blame them at all, I'm just glad I didn't jump up with the glue gun in my hand! He said he was suspicious of me and why his partner was at the ready, but he watched me for bit before getting my attention and had figured out that I was not a robber and that it was a machine in my hand not a gun, although it did look like one and he had never seen one before. Scared the you know what out of me!

 

Cheers

 

Jeff

[Welshbloke]

I've never had much luck with hot glue for anything, really. Certainly wouldn't let it near a motor!

 

I have read that superglue can give off dangerous fumes if heated (as in soldering iron heat, not warm motor heat), supposedly cyanoacrylate contains cyanide which can be released. I'm not sure if this is one of those Internet myths, true under certain circumstances (such as needing a ridiculous amount of heat, no ventilation, and a lot of glue for it to be dangerous) or a genuine risk. I just avoid breathing anything which seems to be scorching the inside of my nostrils and haven't died yet...

[HantuBlauLOL]

Small amount of burned CA fumes won't affect your life, huge amount is a different story.

[cteno4]

True a small bit of hydrogen cyanide gas can be generated if gotten really hot, but the amount in most joints would be tiny and thus the amount made very very tiny! Plus it looks like the monomer (uncured glue) is more prone than the polymer (cured glue) to this and it's temps like 200C plus to do this.

 

I think this worry is from the fingerprinting stuff where the heat up grams of CA to fume a large chamber. Ca fumes are not great to breath, but really an irritant when they bond to skin, throat and eyes with the moisture present. Wear a slightly moist dust mask if you are doing gobs and don't have good ventilation and it helps a lot (done this when using large amounts of CA as a wood filler/finish) and you don't want a lot so smutz blown onto it with a fan.

 

HCN is nasty stuff, my organic chem prof in college was fiddling with scaling up a process that did not like to be scaled for a long time and one faculty meeting it came up that the roof and around the physical sciences building there were a few hundred dead pigeons! All class and prof work was reviewed and they discovered that a side reaction in his experiments probably released a lot. Luckily it was all done in the hood, but if that was not working well or a workman went up there when he was doing this might not have been good! Needless to say his experiments were scaled back and new rules about all hoods being off and nothing released when anyone had to work on the roof!

 

Jeff

[HantuBlauLOL]

That's why I said huge amount of them will do a different story, lol.

[cteno4]

Yes that's true! The prof got in trouble as they were not cleared for doing the quantity he was doing trying to scale the process.

 

Jeff