Dublo -- variations in speed

[GreenDiesel]

A the speed of a couple of my (2-rail) Dublo locos -- my City of London & Barnstaple -- occasionally varies substantially. This usually happens when I haven't used them for awhile (i.e. anything from one day to a week or more). I start running them and sometimes have to turn the throttle to almost full power just to barely keep them moving. Then, suddenly, the motor kicks in and they zoom along at high speed, and then slow down again ... after a few seconds, they'll zoom along again. This usually stops after I've run them for a few minutes, and so far, it's tolerable because this problem doesn't last too long.

 

Does anyone know what might be happening here -- is it something to do with their magnets?

 

Thanks in advance,

Rob

[AMJ]

My old Wrenn BR Std 4 tank loco to get it going you need about 3/4 power but then when it's rolling cut it back to 1/2 or even 1/4 and shes fine else it's off like a hare. It has probably something to do with the heavy body, chassis and older motors. I used to find that it made driving it interesting for those that didn't know the nuiances of the loco. Just lie a real one..

[smokebox]

This can sometime be caused by a lack of lubrication, or old oil that's gone a bit thick. Once the loco has run for a while the oil warms up and gets thinner. Leave it standing and it thickens up again.

[chertsey chopper]

I would start with the simple things first, like cleaning the track thoroughly as it may be erratic in starting suddenly, then there may be cleaner ares where it appears to run better whilst all the while its wheels are picking up traces of grime. Next is contact wipers...likely to be weak after all these years, though they should work even so but given a light pass thru with fine crocus paper ensuring better cleaner contact. Next I'd check the pole pieces and spring pressure as the carbon wears away there may be some loss of spring pressure but not to much degree, however, if the springs and carbons themselves are worn out or broken then they may be worth replacing. There could also be dirt in the commutator, it doesn't sound like the windings are causing problems if it runs quickly. In three-rail H/D the three-rail pick-ups might need a good check and clean(on three-rail HD) and then if necessary you might need to replace the old magnets with the "Neo" variety which are available now.

Insulation is sometimes a problem where there may be something that shorts from time to time particularly seen when cornering. This may be something to check with a continuity checker...i.e., wheels or chassis may be making a circuit when they shouldn't.

 

Just a few pointers, but don't see problems where they may not be...just a thorough clean may be all that's necessary.

 

jules

[stewartingram]

I'd agree with the above comments on lubrication and electrical contact through many years as a service agent. Also brush spring pressure, worth pulling the springs out and retensioning them (crudely) by a slight stretch. Possiblly also remagnetism needed on H/D & Wrenn locos, though this usually causes a solid drop in performance 100% of the time. Cleaning out of slots in the commutator with a pin is good, and don't forget to oil yje armature shaft bearings at either end (usually forgotten). Keep it to a minimum and away from the commutator though! Never remove the magnets without a keeper plate, loss of magnetism results. If they need remag, I still have my machine handy, but the complete chassis needs sending though.

On the 2-6-4T, at the back of the loco is a screw ajuster above the rear bufferbeam, which is supposed to vary the magnetic field strength to give finer low speed control. Useless! take the body off, remove the screw and its bits, replace the body.

Stewart

[Jenny Emily]

This seems to be quite common with old HD locos. Being too young to have owned them when new, I don't know whether this was a characterisation of the design from factory-fresh. I had always assumed that as the motor warmed up it loosened up a little, and probably wore off the layer of dirt that seemed attracted to the wheels and brushes. Some locos were worse than others, though some worked so well that they would run barely on the first notch of the old A3 controllers. However, I later discovered with Bachmann locos running on my Father's old layout that the A3 controller seems to start at what would be on a Gaugemaster controller around 30% power. Warp speed Mr Sulu.

[GreenDiesel]

Thanks for all of this feedback! I'll start by cleaning my track and the HD locos' wheels, checking for extra grime and grit.

Cheers, Rob

[Il Grifone]

Dublo seem to have always suffered from this. The brush spring tension is quite critical. There should be a 'best' setting of the plugs. (This does apply to the ringfield motors.) The fact they run Ok sometimes would indicate this is about right. It is possible the brushes are sticking in the tubes. Remove the brushes and spring (don't let them fly across the room! ). A piece of insulated wire will help to push the brushes out. Then clean out the tube with a cotton bud (possibly dipped in white spirit) and the brushes and springs. Reassemble and all should be well .

Also check the wheel treads and pickups. The later are wire, which is not the most reliable solution.

 

Old dried up lubricant is another possibility. Slacken the two grub screws on the gear wheel and check the wheels turn freely. A Dublo mechanism should run smoothly and easily. Clean and relubricate if necessary.

 

Neo magnets are available as replacements, but again, if the locomotive works well sometimes, this is unlikely to be the trouble.

 

The A3 is a hefty beast designed for the higher current requirements of Dublo motors. Today's puny motors need less current to start and there is insufficient resistance. (My then brand new Trix 56xx always started with a jerk.) I prefer the Marshall III variable transformers (with pulse power - these will tame a Lima pancake!) or an H & M Powermaster. Watch the wiring with these old units. Some of the wire is rubber insulated and this is now 25+ years beyond its 'use by' date.

[Jenny Emily]

 

 

The A3 is a hefty beast designed for the higher current requirements of Dublo motors. Today's puny motors need less current to start and there is insufficient resistance. (My then brand new Trix 56xx always started with a jerk.) I prefer the Marshall III variable transformers (with pulse power - these will tame a Lima pancake!) or an H & M Powermaster. Watch the wiring with these old units. Some of the wire is rubber insulated and this is now 25+ years beyond its 'use by' date.

 

I hadn't thought of that. Having seen the effects of life-expired electrical wiring in a house, I think my Father's three A3, and A2 and C3/T15 combo controllers ought to bow out sooner rather than later. What would be an adequate replacement to power HD locos? They tend to trip out the Gaugemaster controllers as they either draw too much current or the controller throws a fit at the brief moment of shorting that occurs when the pickup shoes short on crossing the points. Would replacement of the power lead be enough to save an A3, or is that idea a non-starter?

 

 

 

[chertsey chopper]

I sold all my old Hornby-Dublo Locos a few years ago but my old H+M Clipper used to power them up well enough. It has the two resistance settings but mine seemed to work reasonably well on either setting...power consumption did seem to vary from one to another, some were also temperamental starters too which is how I acquired my limited servicing knowledge!!

 

Cheers everybody! and Happy New Year!!!!

[stewartingram]

A properly serviced HD loco should draw no more than 0.5A, and indeed any Tri-ang Hornby loco would be the same. I had an ammeter connected during my service days, always a good reliable check on condition & performance.

[Il Grifone]

Replacement of the cable and any internal rubber insulation may be enough (I would value the opinion of a qualified electrician on this one*). Most of my A3's internal insulation is cloth covered, some is pvc. (Surprisingly the rubber insulation is still flexible and shows no sign of cracking - the transformer has been cooked at some time however, so I don't use it, though it still works OK.) The transformers do not incorporate a thermal link as modern transformers do. I believe this is now a safety requirement, but in my experience has written off otherwise perfectly sound equipment. I have had to rewire the internals of one of my Marshall IIIs due to the rubber insulation (low voltage) cracking. The mains cable on these is pvc (I think also on the T15 - mine had a new cable many moons ago, as it had been cut off short), but has the obsolete red, black and green colours (rather nasty as black is now a colour for live wiring! ). H & M controllers suffer from much the same age problems as Dublo unfortunately. (Says he, with a Powermaster plugged in behind him.)

 

* My degree in Electrical Engineering is rather long in the tooth now (and mostly forgotten) and, in any case, did not cover things like wiring regulations etc.

 

Re the current draw of HD motors. Even 500mA is beyond some modern controllers. I have a Mehano one rated at only 12V 5W. HD controllers are rated 9 or 10 W.

I expect an HD or Triang X04/motor bogie to draw about 300-400mA off load.

 

Incidentally the specification for most new Dublo locomotives was to complete 5 laps of an oval of track (about 10 feet) in 25 seconds, hauling 4 superdetail coaches*. The locos with smaller wheels and 1/2" motors were allowed 5 seconds more.

 

* The R1 would just about manage these! I used to consider 5 coaches about maximum loading, though the N2 and 4MT tank would handle more. The ringfield WC and diesels seem upstoppable however. I've had my Deltic pulling more coaches than would run around Dublo curves without falling over. (For those used to plastic stock with pinpoint bearings, Dublo coaches run quite stiffly and are heavy. (Spec. to start rolling on a 1 in 30 - pinpoint stock should run away on a 1 in 100. I have always intended to test the haulage power of a Dublo loco on modern stock but it's one of those things I've never got round to.

[GreenDiesel]

Thanks again for this feedback. I live in Toronto, so we have different controllers available in Canada. I'm not familiar with A3 controllers, etc. My current controllers are a Railpower 1370 and an Athearn. I'm not sure how they compare to the UK ones but these are supposed to be the best quality. The Athearn one in particular runs my HD and Triang locos at a nice, low speed, etc.

 

Having said this, I recently had to replace one of my Railpower tranformers (a slightly weaker version of the one above) as it had simply burnt out after 4-5 years of use. Maybe the older HD and Triang locos drew too much power and burned it out?

 

Cheers, Rob

[Il Grifone]

Thanks again for this feedback. I live in Toronto, so we have different controllers available in Canada. I'm not familiar with A3 controllers, etc. My current controllers are a Railpower 1370 and an Athearn. I'm not sure how they compare to the UK ones but these are supposed to be the best quality. The Athearn one in particular runs my HD and Triang locos at a nice, low speed, etc.

 

Having said this, I recently had to replace one of my Railpower tranformers (a slightly weaker version of the one above) as it had simply burnt out after 4-5 years of use. Maybe the older HD and Triang locos drew too much power and burned it out?

 

Cheers, Rob

 

The giveaway here would be the unit running continuously warm (wall wart power supplies do this normally and are notoriously unreliable). I wouldn't expect a decent power supply to overheat, except under lengthy overload. Dublo transformers were rated 9 or 10VA (I believe they were exported to Canada along with the trains, but were rather expensive - over here & probably even more so there.) I gather Athearn motors used to be current hungry, drawing up to 1 amp. I have to admit to not measuring my Budd railcar (with the rubber band drive) but it ran without problems, at least until the bands failed.

[Il Grifone]

A bit late, but I have found the Dublo specification for current draw - 0.65A max - This is hauling 4 SD6 coaches, so would go higher with heavier loads.

[GreenDiesel]

Thanks for your feedback here...

 

I'm now having a slightly similar problem with my Triang Winston Churchill. On one line of track, that is powered by a fairly new (almost a year old?) Athearn transformer, this loco sucks up the power like crazy. I'll have it at full throttle, and it will crawl round the track -- this problem has just started during the past week or so. But when it's on the other line of track (powered by a 5-year-old Railmaster transformer), it will run much faster with a wider range of speed.

 

Not sure if my Athearn transformer is dying or it the Triang loco needs repairing. FYI, all other locos run well with both transformers.

 

Thanks again,

Rob

[BR60103]

A lot of Dublo/Wrenn locos were banned from Lostock Junction because the controllers had to be turned up so much higher than almost any other loco -- including a number of cast metal kits.

 

My Wrenn Duchess and City will pull a train of modern coaches about 15-16 feet long around my mainline which includes a 1 in 50 grade.

 

I would suggest that you have a power supply that will provide at least 2 amps at 12v (24 watts) for running any of this stock. Also, some of it seems to run better after a short turn around the layout.

[GreenDiesel]

A lot of Dublo/Wrenn locos were banned from Lostock Junction because the controllers had to be turned up so much higher than almost any other loco -- including a number of cast metal kits.

 

My Wrenn Duchess and City will pull a train of modern coaches about 15-16 feet long around my mainline which includes a 1 in 50 grade.

 

I would suggest that you have a power supply that will provide at least 2 amps at 12v (24 watts) for running any of this stock. Also, some of it seems to run better after a short turn around the layout.

 

 

Thanks, David. Maybe I'll have to get another controller in the future and double-check that it has enough watts.

Rob

[Il Grifone]

Tri-ang motors shouldn't draw an enormous amount of current - about the same or less than HD. I would check the motor for muck on the commutator. Clean the surface carefully and clean out the slots - I use a wooden toothpick - no abrasives. Also check the chassis runs freely and that the pickups are working correctly - they sometimes get bent and partly jam the wheels. If the motor runs warm off load, I would suspect a shorted winding, especially if there is any tendency to stick/reluctance to start. Luckily they are quite easy to obtain on eBay. I believe the modern Hornby motor (from the0-60T chassis) will fit if you change the gears, but I've never tried.

If the other locos run well, the power units are absolved from blame. Dublo or Tri-ang motors need more current than modern motors, but shouldn't require more than about 800mA (Dublo controllers are rated 8/9 watts @ 12V).

 

I am currently using an H & M Powermaster (o/p 2½ A @ 12V). This was struggling with my TTR compound*, but I traced the trouble to the armature shorting to chassis (there isn't much clearance and it was rubbing against the gearwheel) and now she is fine - just needs some new wheels - the borrowed set slip on their axles.

 

*These suck up current due to the reverser - a large coil in parallel with the motor - and the field winding - they are effectively 6V motors, which, of course, means twice the current. Trix transformers are rated 3A! for two trains, but I haven't the courage to plug mine in. I don't need any 230V fireworks! (Don't tell the TTRCA, but I've disconnected the reverser and fed the field winding through a bridge rectifier (4x 1N4007 diodes), which makes her reverse properly on DC.

[GreenDiesel]

Thanks for this feedback, David. I'll check the motor of my Winston Churchill then. Rob