Poor-running Heljan 47

[bunjy76]

Hello all,

I have an OO gauge Heljan 47 which i’m running on my DCC layout. I bought about 3-4mths ago, initially it did run very well, however i cleaned up the wheels which were pretty mucky and after that all was fine. However recently it has suffered a loss of power/traction, it’ll run for a couple of feet and then come to a standstill even though the motor seems to be running at full power. If i give it a little nudge it will move of again but then do the same thing again. I’ve checked and cleaned the wheels again, and it hasn’t suffered any drops or collisions so i’m at a bit of a loos as to why it’s just given up on me. Seems to me there is a problem between the motor and axle/wheels. I’m not too technical so haven’t really had a poke around inside. Any ideas?

Mod: Topic moved to the Heljan forum section.

[Oxley]

There's a plastic cup where the drive shafts connect to the worm gear on top of the gear towers
and the cups, which are just a friction fit, have a tendency to split and you basically lose propulsion.

Gaugemaster are the Heljan spare parts agents now. Lots of luck.

[Bigmet]

Further to which, if you put dots from a spirit type marker on the wheel rims of the driven wheels you will more easily be able to confirm that drive is lost on one of the bogies, before 'going inside'. Try the loco in both directions too, I have seen one where intermittent drive loss happened on both bogies...

You may yet be lucky, and find that it is the moulding in the flywheel that is only slipping rather than damaged, in which case a dot of cyano to resecure is all the repair required.

This is a 'universal problem' on centre motor chassis, seen it on all of Bachmann, Heljan and Hornby mechanisms; these being the three brands that have got a couple of decades history of this type of drive in OO. (I expect the later entrants will 'catch up' in due course.)

[bunjy76]

Ok, i’ll try with all of the above and let you know how things turn out. Cheers for the responses

[mossdp]

The drive shaft cup coming loose at the worm end is a very common problem with these models. I have fixed several myself with a drop of glue. Best to do both bogies at the same time as the other one may cause trouble later on. Sometimes, you can see a tiny hairline crack where the cup meets the motor shaft.

[bunjy76]

It’s sounding like that is probably whats at fault. Will take a look. Cheers!

[bunjy76]

So further to everybody's responses, i’ve had a delve inside the loco, removed the motherboard to get a better look. Everything seems to be intact, the plastic ‘cups’ which hold the axel don’t look to be broken, and there is nithing else loose or rattling around. I’ve rotated the cogs and the proceed to turn the wheels in both directions, so i’m still at a bit of a loss. I haven’t tried it on track again yet so haven’t been able to check if both wheel sets are moving in unison, i thought it would just be a loose axel as everybody suggested. Anyway, i’ll attached some pics of the inside, any further help would be appreciated. : ))

[Peterm]

Prevent the motor from turning by placing a finger on a flywheel and see if you can then turn either cardan shaft. Without exerting a huge force, you shouldn't be able to turn either shaft. If you can, then you need to drop the bogie out, remove the cup from the flywheel, clean up with IPA or Metho, glue it in, re lubricate and put it all back together. If you find a cracked cup you might be able to get new ones from the main dealer, Guagemaster?

[bunjy76]

Great, i’ll try that and let you know. Appreciate your help.

[Bigmet]

... the plastic ‘cups’ which hold the axle don’t look to be broken, and there is nothing else loose or rattling around. ...

They don't need to be broken to slip, and anyway it is often hard to see a small crack in plastic component.

... I’ve rotated the cogs and they proceed to turn the wheels in both directions, so i’m still at a bit of a loss. ...

Guessing here that by 'cogs' you mean the large brass flywheels either end of the motor? With no load on the wheels from the mass of the model on the rails, the slipping probably won't happen.

... I haven’t tried it on track again yet so haven’t been able to check if both wheel sets are moving in unison...

This is where you should start any investigation: first looking for the evidence with the loco running on track, which is where it has to work. (With experience you can substitute testing such as suggested here:

Prevent the motor from turning by placing a finger on a flywheel and see if you can then turn either cardan shaft. Without exerting a huge force, you shouldn't be able to turn either shaft.

)

[bunjy76]

Cheers for the advice.

[bunjy76]

Cheers for the advice.

[Metadyneman]

I have had this problem with many of my Heljan locos in the past and it is really the "Achillies heel" of their mechanism design. I have found that the only way to resolve it with any degree of success is to clean up the spindle and the plastic cup then glue it back on to the spindle with Araldite. By far the worst offender for this problem is the Hymek. All four of mine have suffered drive loss from either one or both bogies requiring the above solution to be administered. Purchasing a new part from Gaugemaster is also a solution but then you run the risk of the same thing happening with the spare part eventually. Araldite has proved itself (on my models at least) to be a far more permanent solution to what is in fact a very irritating problem.

[Bigmet]

Interesting, I have only seen the problem on the 47s, immensely popular when first released twenty years ago, and several friends bought them. I thought the frequent stiffness of the bogie gear trains probably contributed. Read reports of this happening on other Heljan models but not seen any others personally so far, including on my modest Heljan fleet (15, 16, 23, 26/0.)

...By far the worst offender for this problem is the Hymek. All four of mine have suffered drive loss from either one or both bogies requiring the above solution to be administered...

Any chance that these are simply the ones you run much more than whatever other Heljan models you own, because they are such good looking machines?

An alternative explanation is that since these are assemblies of what are in design clearly standardised parts, it's variation in dimensional control of the batches of components that go into specific builds of models.

...a very irritating problem.

My take is that fortunately that's all it is. Once you know what you are looking for, it's quickly repairable. I'll accept that, for the net benefit that these centre motor twin bogie drives (all makers) are in other respects well superior to the alternative methods.

[mossdp]

The faults in the cups are hidden by the other plastic parts around them. Even when taken apart, the crack can be quite hard to see.