ClydeIron Posted March 13, 2014 Share Posted March 13, 2014 Hi all, I thought this query might be best suited for the motors section! I'm doing some work on a HD Class 08 and have a small problem (you always know when something fun's coming when people say that, don't you?)... Upon removing the body I found the main wire from the pickups had been disconnected, where it had become detached from the choke, which had itself essentially melted - the yellow plastic sleeve had burned away. Last night, after fitting a new choke (the condenser was OK) I managed to get power through the motor, with the result the 08 burst into life again. However, after a few minutes light running it became very very hot, with light smoke coming from the armature and between the wheels. A cursory inspection suggested doesn't appear to have been seriously damaged – in fact it seems happy enough to take power again – but I was wondering if you have an idea for the cause. I've never worked with this design of motor, but suspect a complete strip down may be needed. All views are more than welcome. many thanks in advance, Chris Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted March 13, 2014 Share Posted March 13, 2014 The age of this model makes it very likely that the magnet field strength is way below original value. That means much more motor current, thus the heating. Replacement 'neo' magnets are available or alternatively seek out someone offering a remagnetising service. Best to sort this before any further running or one or more windings will need replacement... Link to post Share on other sites More sharing options...
Titan Posted March 13, 2014 Share Posted March 13, 2014 Could be more than one possibility - either the motor is overloaded due to excessive friction, or the magnet is too weak so that excessive armature current is required to make it go. Also if some of the windings have shorted out due to the insulation melting, it might not stop the motor running but the more that are shorted the higher the current drawn which would result in rapid temperature rise and failure. If any of the windings appear black it is not a good sign. I think the first point will be a complete strip down and inspection. See if the wheels and axles move freely without the armature in place. Check resistance across two adjacent commutator segments, they should all be the same. It would be worthwhile getting a replacement neo magnet as mentioned above in any case as they offer a significant performance improvement over a good standard magnet let alone a weak one. Although one side effect I had on my Wrenn example was that the magnet was strong enough to occasionaly lift the metal hook of the tension lock coupling under the cab which made for some coupling difficulties! I think the end float on the armature can be adjusted by the screw on top, make sure that is correctly adjusted. Link to post Share on other sites More sharing options...
ClydeIron Posted March 13, 2014 Author Share Posted March 13, 2014 Thanks guys, that's really helpful. One of the problems is that I don't know the provenance of the loco - so I don't know if it ever has been stripped down, bits replaced etc. I have to say that my initial thoughts were that it hadn't, so the magnet theory seems more than plausible. I'll make sure to have a look at the armature too when I remove it. Having never stripped one of these motors down before is there anything I should look out for? I have Servicing Leaflet 14 to hand, so will be using that as a guide, but any tips would be appreciated. I've worked on HD locos before but for some reason never the 08, so it's a new animal to me. Once again my thanks. Chris Link to post Share on other sites More sharing options...
BrushVeteran Posted March 13, 2014 Share Posted March 13, 2014 Having owned two of these in the past which both suffered with the same symptoms I can confirm that it more likely to be weak magnets. They are quite simple to change and it is worth changing the armature at the same time. Link to post Share on other sites More sharing options...
stewartingram Posted March 13, 2014 Share Posted March 13, 2014 The age of this model makes it very likely that the magnet field strength is way below original value. That means much more motor current, thus the heating. Replacement 'neo' magnets are available or alternatively seek out someone offering a remagnetising service. Best to sort this before any further running or one or more windings will need replacement... If you need it remagnetising PM me. I still have the tool from my servicing days. Whatever you do - do NOT remove the magnet. Most of the magnetism will be lost especially with HD/Wrenn motors. A quick service and remag and it will be at least as good as new, they were built to last. Stewart Link to post Share on other sites More sharing options...
DCB Posted March 19, 2014 Share Posted March 19, 2014 My brand new Wrenn 08 did the same 30 years ago, when I was running in, in fact it got so hot that it melted the solder on the Commutator and I had to re solder the wires. The root problem is the reduction gearing is a joke about 10 to 1, the motor cannot spin up to a reasonable speed without the loco running ridiculously fast so it runs slowly and overheats. To fix it, take the motor apart, clean the melted plastic off the inside of the magnet clean everything, unscrew the axle gear so it runs free, re assemble, oil the bearings with 3 in 1 oil, ensure the end float balls are still in the armature bearings,, power the motor up and adjust the armature end float to get maximum speed with half power or so on the power unit, In my experience this is critical on all H/D ringfield motors. At some pointyou need to decide whether you want an authentic 1960s toy or a serious shunting loco, if you want a serious piece of kit take off the dummy frames, pry off a fly crank on the back axle push the axle out and change the gears for Romfords, I think mine are 60 to 1, I am not sure if I had to bore out the worm, it was 30 years ago. Refitting the fly crank is a challenge, but ever since my 08 has been a useful tool, even flat out it can barely exceed the scale 25 or 30 mph the prototypes managed in their early years, and I have had no motor trouble since, and it makes a Bachmann gronk look very silly when it comes to actually pulling wagons. Link to post Share on other sites More sharing options...
ClydeIron Posted March 19, 2014 Author Share Posted March 19, 2014 Thank you very much guys - I'll be starting a full strip down shortly. I may even post pictures if I remember!! Much appreciated!! Chris Link to post Share on other sites More sharing options...
ClydeIron Posted April 3, 2014 Author Share Posted April 3, 2014 Finally got round the stripping the motor down to components, and yes, you guessed it, while two of the windings were nice and tight, the third was black and untangled. Time to hunt for a new armature! The magnet was pretty dire too!! Many thanks for your help again. Chris Link to post Share on other sites More sharing options...
jimwal Posted April 11, 2014 Share Posted April 11, 2014 Just seen this thread. The HD and early Wrenn 08s were prone to armature insulation melting. New insulation, rewinding and remagnetizing will cure the problem as I've done these myself previously. A neodymium magnet will certainly improve the power but the strength of the magnet makes it virtually impossible to get smooth slow running. This seems to be down to the three pole armature. I obtained a five pole 3/4inch vertical armature for the 2-6-4T and fitted in place of the pole pieces and block magnet, one of the larger neo ring magnets intended for the diesels. This worked very well, the armature can be made to barely turn giving very good shunting. I also have a 'Coronation' fitted with a five pole armature with neo block and pole pieces which has good control and plenty of power. I bought these armatures many years ago I believe from one of the Wrenn collector groups at an ealy Warley show at the NEC. I don't think a 5/8inch version was ever produced for any of the ringfield types. Jim Link to post Share on other sites More sharing options...
DCB Posted April 18, 2014 Share Posted April 18, 2014 ClydeIron Try winding the windings back on, re solder them to the commutator and seal with Araldite, mine has been fine for the past 20 years since I did that. Re Jimwal, I too fitted a Ring Magnet, Deltic Type from a 6 wheel power bogie, to a 2-6-4T chassis but it was anything but simple as I had to grind away an awful lot of chassis and getting the armature and magnet in was quite "Challenging!" It had small wheels and ran as a sort of Std 3MT tank with a Triang 3MT body modified to look something like a 3MT tank, not much I admit, but it worked for several years mainly as a station pilot heaving 8 coach rakes of H/D metal coaches up a 1 in 30 gradient. The main problem I find is the H/D vertical motor and Ringfield gearing is too high, giving around 4 times the RPM of the 1/2" Motor as far as I can tell. A H/D Ringfield Castle with Triang worm and worm wheel works very well in a 56XX 0-6-2 as long as you don't mind running it flat out, likewise the 08. My approach is to change the gearing and get good slow running that way at the expense of top speed, rather than change the magnets which simply were not available 20 plus years ago when my brand new 08 melted its armature wires from the commutator. Link to post Share on other sites More sharing options...
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