Revitalizing Wrenn locos.

[Re6/6]

I have acquired some Wrenn locos for disposal for a friend. On checking them they are very sluggish when powered up. Even the so-called 'mint boxed' aren't much better. Is there any advice from anybody with experience of this with these type of locos (including, I suppose, Hornby Dublo types)? Is there any 'common fault' with long stored locos, or will I have to have them perhaps re-magnetized or something professionally? I've taken out of it's box an absolutely mint example and it will only just move. Should I persist with trying to coax them back to life?

Thanks

John

[stewartingram]

When I did repairs as a service agent, I always enjoyed doing the HD/Wrenn locos, they had a quality build feel compared to the Triang (Note - nothing to do with fidelity to scale or looks!), a bit of traditional engineering. Spares were rarely needed except for occasional replacement brushes or sometimes an armature, the latter probably needing a rewind. Out of touch with the latter nowadays but there used to be a local guy who did these, take you old one in and swap it for a ready re-wound one. Oil on the commutator & brushes is a no-no.

A good clean up, especially around the commutator & slots; a tiny spot of oil on top & bottom armature bearings along with axle bearings and valve gear usually does wonders. They were prone to losing magnetism, whatever you do DO NOT remove the magnet. If they need re-mag & you can't find anyone local, pm me, I still have the gear. There has been talk on here of replacement with a modern type of magnet but I've not done this, I have heard they can actually be too strong? A loco in good nick will draw about 1/4 amp at max, if it goes up to 1/2 amp that is a sign of magnet trouble, but do the clean & oil 1st. Sometimes brush spring adjustment is needed, GENTLE stretching of the brush spring can help.

If you have a 2-6-4T, they were fitted with an adjusting screw in the back, above the bufferbeam. Supposed to change the magnetic field to give better shunting control, but better if this is removed. Take the body off, remove the adjustment screw and its associated bits, this does help.

Hope this helps, get back to me if you need more.

Stewart

[Guest dilbert]

I would think that Wrenn stuff these days would be aimed more at the collector's side of the hobby. If that's the case then I suppose that most models would end up in display cases, so is there a need for fully functioning models ? I don't know, but might be worth doing some additional research.

 

If you are in possession of some of the rarer items, then the extra effort may be worth while to make to get into a decent running condition... I must admit that an N2 0-6-2T in GWR colours is not at all enthusing to mine eyes, but could be ambrosia to someone else.

 

Consultation of Pat Hammond's Ramsey's guide will most likely help as well ... dilbert B)

[beeman]

A couple of points I feel Stewart has missed are as follows. Has the loco had a lot of use, a pointer to this would be the wear on the rods/pins, plating on the wheels. If this is the case then also the commutator may need a skim in a lathe to correct any wear.. I recently dug out my old Wrenn Westcountry which needed this. along with cleaning the com slots, this made a big improvement. Keep the spring pressure to a minimum, but not too low to cause arcing. If the com is worn it will cause arcing due to it being eccentric. I have posted quite a bit on the Neo magnets. One firm specialises in replacements for Dublo, So I have doubts that they would be selling these knowing it could cause a motor to burn out due to being too strong. I replaced the armature for a five pole,[ bearings reqd.], then a Super Neo for the 'Rubber magnet' some time back in an old Scotsman. On DCC in its original state some 35 odd years old, the slowest I could get the loco to run was 1 rev/sec of the drivers after fitting a chip. After the replacement 5 Pole this increased to 5 secs for one rev, and after the magnet 10 secs/rev.The motor current was well reduced , So I was well pleased. Ok these have been my findings as a Retd.Elec/Mech Eng. perhaps others 'experimenting' have just had bad luck or may lack experience,it would be most unfair for me to judge. I cannot understand why Stewart suggested NOT to remove the magnet. It would have to be removed for remagnetising. The only reason I can surmise is that you may loose its correct position,This is related to the position of the brushes and can be also as to how the armature is wound. So if you do remove it, mark it. I hope my observations are of interest.

Beeman

[stewartingram]

"I cannot understand why Stewart suggested NOT to remove the magnet. It would have to be removed for remagnetising"

I'm sorry but I have to disagree with this. During my training in Mech & Electronic engineering, (too many years ago!) I was taught a number of times ALWAYS to have a complete magnetic path otherwise the magnet would deteriorate. Way back then magnets (in general, not HD) were supplied with a keeper plate which was only removed after installation. Things may have changed nowadays maybe, I've no idea of the current scene in industry. Perhaps techology has improved? However the HD magnets are from that era, and I can personally vouch for a loss of strength of magnetism on every magnet I've removed from a HD motor. Not that it bothered me as I was cleaning or whatever, and re-magnetised it after reassembly. My machine is a professional one designed for the job, it will take a loco chassis/motor complete. I've lost count of the number of locos I've had brought to me where someone has had the magnet removed for remagnetisation, and found that all it needed was doing it situ.
I agree about the wear on pins and commutator. I didn't mention this at this stage, trying to keep it simple, but I sometime skim the commutator in situ with a craft knife blade. Not for the faint hearted or novice though, as more damage can be caused if not careful.
As far as Neo magnets are concerned I have never tried them nor found the need, only passing on comments I have heard. I do not wish to degrade the product, just feel it fair to make up your own mind. I would add that I run using a very old homebuilt transistor controller which does overcome lots of poor running from "simple" designs of locos. For instance a Triang X04 Jinty motor will pulse over between poles at approx 1 second per pole, the limiting factor on slow running being simply poor pickup from the rails.
I would add that I'm not being unfriendly here, just trying to help
Stewart

[sagaguy]

Whatever you do,do not remove the magnet if it is a vertical armature,the armature & magnet including pole pieces are magnetised as an assembly.You can remove ringfield magnets if you are conveting from 2 rail to 3 rail which i have done on HD & Wrenn locos,you have to rotate the magnet 180 deg.otherwise the loco runs in reverse.

You could try Superneo magnets but ihave not had any experience with these.Wrenn & HD locos do lose magnet power if left in storage for a long period of time.

Regards,Ray.

[sagaguy]

A couple of points I feel Stewart has missed are as follows. Has the loco had a lot of use, a pointer to this would be the wear on the rods/pins, plating on the wheels. If this is the case then also the commutator may need a skim in a lathe to correct any wear.. I recently dug out my old Wrenn Westcountry which needed this. along with cleaning the com slots, this made a big improvement. Keep the spring pressure to a minimum, but not too low to cause arcing. If the com is worn it will cause arcing due to it being eccentric. I have posted quite a bit on the Neo magnets. One firm specialises in replacements for Dublo, So I have doubts that they would be selling these knowing it could cause a motor to burn out due to being too strong. I replaced the armature for a five pole,[ bearings reqd.], then a Super Neo for the 'Rubber magnet' some time back in an old Scotsman. On DCC in its original state some 35 odd years old, the slowest I could get the loco to run was 1 rev/sec of the drivers after fitting a chip. After the replacement 5 Pole this increased to 5 secs for one rev, and after the magnet 10 secs/rev.The motor current was well reduced , So I was well pleased. Ok these have been my findings as a Retd.Elec/Mech Eng. perhaps others 'experimenting' have just had bad luck or may lack experience,it would be most unfair for me to judge. I cannot understand why Stewart suggested NOT to remove the magnet. It would have to be removed for remagnetising. The only reason I can surmise is that you may loose its correct position,This is related to the position of the brushes and can be also as to how the armature is wound. So if you do remove it, mark it. I hope my observations are of interest.

Beeman

 

 

As a further thought,when i had my first HD Silver King in the early 1950`s,you could stick a screwdriver to the loco housing & would have a fair pull to remove it,that`s how strong the orginal HD magnets were.In the past,I have removed coupling rods,reamed the holes & fitted brass tube bushes.As for skimming commutators in a lathe,beware,I tried this some years ago & after spending a lot of time machining the worn shaft & loctiting a sleeve & turning that to size,I thought i`d skim the commutator as well.Result?,one commutator in a totally different place from where it was originally!!,I had to send it away for a replacement.

[stewartingram]

Result?,one commutator in a totally different place from where it was originally!!,I had to send it away for a replacement.

 

Exactly my point in not mentioning it.

[roythebus]

Good old vintage technology. This is the first thread on here where I've seen the word "lathe" mentioned!

 

The type 1 diesels (class20) were prone to lose their magnetism for some reason.

[beeman]

I disagree entirely about re magnetising motors as a whole.The magnet force in the armature is created by the current flowing thro it. This creates a pole which is either attracted to or opposes that contained within the fixed magnet,thus causing the armature to rotate, the poles being 'switched ' by the commutator. This applies whether a block type as in X04 or ring magnet is used.. The steel that the armature stampings are made from is a type that has low magnetic retention, but no steel based alloy is completely NON Magnetic, and if the armature was not magnetic why put any steel into it ,make it out of plastic ? Yes there are some hybrid motors that d'ont have any metal in them, relying purely on the magnetic field created in the winding. These are normally too expensive for Model railway general use. Likewise if a motor MUST be re magged with the armature in situ, why do Hornby sell 5 Pole armatures as a seperate spare ?. Sagaguy also referred to how strong the original mags used to be, so why not Neo's. I concur with Stewart about a magnet requiring a 'keeper', when NOT assembled into a motor, but when in the motor the armature acts as the 'keeper', the smaller the gap between the two parts the better, both for magnet strength retention and motor performance. These are reasons for smaller more powerful motors of today than yesteryear, along with better /closer manufacturing techniques. I would add I spent a number or years as Applications Engineer with a company manufacturing Solenoids/electromagnets, Sorry to Disagree. Beeman.

[sagaguy]

Exactly my point in not mentioning it.

 

 

There`s more to restoring old HD & Wrenn loco`s than meets the eye,best left to the proffesionals,There are a few around,Model Railway Doctor springs to mind!!

I certainly wouldn`t tinker with my original HD 3 rail emu,far too valuable,(well,to me anyway)

 

Ray

[sagaguy]

I disagree entirely about re magnetising motors as a whole.The magnet force in the armature is created by the current flowing thro it. This creates a pole which is either attracted to or opposes that contained within the fixed magnet,thus causing the armature to rotate, the poles being 'switched ' by the commutator. This applies whether a block type as in X04 or ring magnet is used.. The steel that the armature stampings are made from is a type that has low magnetic retention, but no steel based alloy is completely NON Magnetic, and if the armature was not magnetic why put any steel into it ,make it out of plastic ? Yes there are some hybrid motors that d'ont have any metal in them, relying purely on the magnetic field created in the winding. These are normally to expensive for Model railway general use. Likewise if a motor MUST be re magged with the armature in situ, why do Hornby sell 5 Pole armatures as a seperate spare ?. I rest my case. Oh by the bye I spent a Number of years as Applications Engineer for a Company producing solenoids,and electromagnets. also Sagaguy has also referred to how strong the original mags used to be, so why not Neo's. Sorry to Disagree. Beeman.

 

 

Actually,Meccano instruction leaflets packed with their locos specificaly told you not to dissamble the motor as it would lose its power,something i can vouch for when converting a Wrenn Duchess to 3 Rail a few years ago.The magnet had to be rotated 180 deg to make it run in the right direction,I had to send it away to be remagnetised.The warning was also in the Meccano magazine at the time in a description of building HD locos.They should know,they made them.

 

Ry

[stewartingram]

I disagree entirely about re magnetising motors as a whole.The magnet force in the armature is created by the current flowing thro it. This creates a pole which is either attracted to or opposes that contained within the fixed magnet,thus causing the armature to rotate, the poles being 'switched ' by the commutator. This applies whether a block type as in X04 or ring magnet is used.. The steel that the armature stampings are made from is a type that has low magnetic retention, but no steel based alloy is completely NON Magnetic, and if the armature was not magnetic why put any steel into it ,make it out of plastic ? Yes there are some hybrid motors that d'ont have any metal in them, relying purely on the magnetic field created in the winding. These are normally too expensive for Model railway general use. Likewise if a motor MUST be re magged with the armature in situ, why do Hornby sell 5 Pole armatures as a seperate spare ?. Sagaguy also referred to how strong the original mags used to be, so why not Neo's. I concur with Stewart about a magnet requiring a 'keeper', when NOT assembled into a motor, but when in the motor the armature acts as the 'keeper', the smaller the gap between the two parts the better, both for magnet strength retention and motor performance. These are reasons for smaller more powerful motors of today than yesteryear, along with better /closer manufacturing techniques. I would add I spent a number or years as Applications Engineer with a company manufacturing Solenoids/electromagnets, Sorry to Disagree. Beeman.

 

Removing the MAGNET from the chassis (HD/Wrenn) or motor (Triang?Hornby) and re-magging it ON ITS OWN means there is no keeper plate. Removing the ARMATURE is irrelevant to this point. On a HD loco (A4, Duchess etc) the magnet is a block; the curved pole-pieces held to the magnet by a screw through it. The armature is relevant only in discussing the motor operation, the pole-pieces form the bulk of the magnetic path but NOT a complete one especially if the 3 components are removed from the chassis as a whole. The HD armature removal is obstructed by the pole-pieces, many people remove these to get the armature out and thus lose magnetism. It is possible with care to rotate them out of the way to get the armature out, but at this point I re-mag anyway as a matter of course when re-assembled. In the 20 or so years when I professionally repaired these locos I have remagged 100's of these locos, the current before & after showed the difference as well as the improved performance.

The Triang X04 motors seemed to have better magnets though, removing those on their own was possible but there was a small degredation (higher current) when re-assembled. Good practise dictated that I didn't do it anyway.

Stewart

[bertiedog]

I well understand the comments that the magnets should be re- magnetised outside the motor frame, but there is a big but, Hornby never designed the models with that in mind, they actually made a re-magnetiser, sold to dealers who undertook servicing the Dublo locomotives.

 

 

It consisted of a sealed very heavy steel box about 18 inches across the front and a foot deep, finished in crackle black, with controls in nickel plated brass etc on the front, mains power lead at back supplied a low voltage charger inside the unit.

 

It had a slot like a post box slot into which any of the Hornby OO locos could be inserted, and a hole on the top, down which a nickel chromed steel core rod, (about 2 inches dia.), was inserted to bear on the magnet, or the pole pieces.

 

The lower pole piece, hidden in the machine, had a large coil around it, which was connected by a passing switch to a charged capacitor of very large value.. After leaving ON to charge, the switch was thrown, and the field produced by the discharge was sufficient to re-magnetise the magnet in situ, they were alnico and do not require a massive field to do this.

 

I believe (from the owner of one, Hamblings Models), that the coil was about 20,000 turns, and the capacitor about 20,000micro farads, I did try to examine the internals, but it was sealed very carefully. I was told the whole device was designed by Mr Graham Farish, and made at his Bromley factory, where they made radio components.

 

Mr Farish was a bit of an expert on magnets being a business neighbour to Lowther Loudspeakers in Bromley, who made the best Alnico magnets in the world at the time, via a patented secret process for their horn loudspeakers.

 

The machine could also do Tri-ang Rovex motors in situ, and any other motor that would fit the slot, they all magnetised easily.

 

The modern alternative is a neodymium replacement, but these look un-original, and same sized ones are often too powerful, it is best to choose a smaller one and pack with steel to fit.

.

The powerful field causes cogging, and a lot more noise, especially if the bearings are loose.from wear, but the smaller ones, plus the packing give the right strength.

 

Original Ringfields had a warning that they must be magnetised in situ, never take apart was the instruction from Binns road.

Hope this helps,

 

Stephen.

[bertiedog]

"They were prone to losing magnetism, whatever you do DO NOT remove the magnet. If they need re-mag & you can't find anyone local, pm me, I still have the gear.

 

Do you have working Hornby (Binns Road) re-magnetiser? and have you ever found the spec, or circuit, they used.(there once was a full handbook with them, but Hamblings had lost theirs in the move from number 10 Cecil court to number 22..!..)

 

 

I worked at Hamblings, who had one, but it was riveted closed, and un-openable, so without a circuit I never found the coil details or the value of the capacitor.used.

 

Mention was made of a coil of 20,000 turns, and a capacitor of 20,000 micro farads, very large for the 1950's. Another electronics expert said there were two coils, one discharged into another like an Tesla coil in reverse, to create a huge current for a moment, but I am still in the dark as to how the massive pulse was made.

 

I was told that Mr Graham Farish designed and built the unit for Hornby, as he had a radio spares factory at Bromley and had made magnetisers for Lowther Loudspeakers, who were nearby, and these magnetised liquid Alnico as it was cast, resulting in "super magnets" for the 1940'50 period.

 

 

I did build my own unit based on a coil from a radar set and modern capacitors discharging, but the field is nowhere as good as the factory unit, and some idea of what they used would be useful, even after all these years, mainly as a matter of curiosity.

[Il Grifone]

Quote (from memory so not exact) from 'Tri-ang Railways - The First Ten Years'. "Removing the magnet will result in loss of magnetism. There is plenty left, but it is a pity to waste any." Meccano were equally emphatic. It can be done with a keeper across the magnet and then sliding the pole pieces out, but care is required - leave well alone if not essential. The mechanisms were originally assembled and then magnetised (Meccano Magazine)

 

The usual reason for sluggish operation is dried lubricant in the mechanism. White spirit will shift it. Slacken (don't remove if you want to keep them) the two grub screws on the worm wheel. This frees the mechanism and its operation can be checked. It should run freely and smoothly. I have found some two rail locos to suffer from bad quartering due to slippage of the bushes - correct and lock with superglue or the correct version of Loktite. 3 rail locos are immune thanks to the splined axles.

 

Where necessary, I use two 6mm cube neos padded out with two 3mm washers. These have two advantages over the 'original size' replacements - cost and the resulting strength is similar to the original magnets.

[bertiedog]

The armatures can have the commutator skimmed lightly in a lathe, but it has to be done in a lathe fitted with accurate collect chucks or specially drilled split collets, three jaws chucks will not do. inverted centres will work.

 

 

Generally Hornby Commutators are true, but can develop a groove due to wear, and this can be machined away. Also a brand new loco can be Blueprint assembled, to really fine tolerances and this results in the finest running, everything to spec or better.

 

One of the very best runners I have is a Hornby Castle, silent, powerful, and glides along on about 4/5 volts.. it was built up from junked parts in the workshop!! Nothing un-Binns road is fitted,....., just very carefully assembling everything, polishing all parts to mirror finish in the motor, polished axles and gears, full lube with silicon oils and greases. The only parts changed were the brushes , which are gold dust impregnated type from other motors. as I found the Hornby ones a bit hard and brittle, (they varied a lot).

 

 

Stephen.

[Re6/6]

A very big thankyou to you all. It never ceases to amaze me all the knowledge that's out there! The above is very helpful indeed. I'm well out of my 'field of expertise' with these things.

As has been said, the better boxed locos will go to 'collectors' and probably will never see the light of day, but if I was to pay big bucks for a 'mint' model I would certainly expect it to go nicely!

 

Although not the most accurate in looks, they give me a certain 'nicely engineered' feel. It's turning out to be be quite fun and satisfying to get these things working again. Probably something to do with my early Dublo days.

[Barry Ten]

My Wrenn Castle was the best running loco I had as a kid - virtually silent and strong as an ox. When I tried re-running it again after my return to the hobby it was very sluggish, but I took no remedial action since it wouldn't go through my points anyway. One day I'd quite like to have a loop of coarse scale track it could run on, for old time's sake.

[bertiedog]

Checking up about magnetisers, it seems that the power required is quite considerable, several K Joules is quoted for small commercial machines, but there are references to a 12 Volt unit made by a Hornby collector, that was a simple massive coil, flashed on to a car battery, and this could cope with Hornby Alnico magnets.

The kind of power that can be safely flashed from a car battery is about 100 amps max, so the power available would be about 1.2 K watts, therefore about 1200 joules in a one second flash surge.

There are powerful lab units at 5.2k Joules, so 1.2 kjoules or a bit less would sound feasible , A coil would have to be built to take about 70 plus amps, and calculated to have the max number of turns at that current.

With a capacitor unit a step down transformer must be used, a capacitor can't deliver such currents, but could delver a high voltage pulse, converted to a lower one at large current., and I assume this is what Hornby did in the commercial unit.

 

All of this is curiosity only, neodymium magnets offer a simpler practical solution, although un-original. On appearance the smaller magnet could have a coating of resin filler added and filed to shape to give the correct shape, this will not affect the magnet, and they last indefinitely.

[Jim49]

Hi John. From my experiences with old H/D or Wrenn locos can I suggest that you try taking the

body off and run it just as a chassis?. These bodies are diecast metal and the weight may prove

too much for a motor that is already on the weak side after years in storage, especially if the

original oil or grease lubricant has solidified with time.

 

If there is no or little improvement with the body off, support the chassis at each end so that

the drive wheels are clear of the track and then connect the supply from your controller direct

to the motor. Crocodile clips can be used to attach the wires to the brush holders(?) on the chassis.

Doing it this way means that you avoid any problems with dirty wheel treads or pick-ups and the motor

has only to turn the wheels without the weight of the chassis to overcome. If it works, eventually

the commutator face should polish up and the pick-ups should clean up a little as well although both

they and the wheel treads should be cleaned as a matter of course.

 

I had to do this many years ago with a "bargain" Wrenn Standard tank that I picked up at a show. When

I took it to my club to show it off, the bl**dy thing would hardly move despite the controller being

set to maximum. I spent the rest of the night tinkering with it as described until it finally freed off

and started to run properly.

 

Best of luck,

 

 

Jim

[Jenny Emily]

My Father built a remagnetiser for his collection back in the early 1990s. He was given the plans by a gentleman who in turn had got them from a source that may have been Meccano. It consisted of two coils that sat on adjustable steel bars that sat either side of the magnet still in situ on the chassis. It worked quite well, and was powered via a 12V car battery and an ignition switch from an old Austin Metro. I must have a hunt around at some point and see if the beast still a) exists and B) works. It wasn't for the faint hearted to operate, nor those with a pacemaker. Advice was also to never wear a watch when using it.

[bertiedog]

My Father built a remagnetiser for his collection back in the early 1990s. He was given the plans by a gentleman who in turn had got them from a source that may have been Meccano. It consisted of two coils that sat on adjustable steel bars that sat either side of the magnet still in situ on the chassis. It worked quite well, and was powered via a 12V car battery and an ignition switch from an old Austin Metro. I must have a hunt around at some point and see if the beast still a) exists and B) works. It wasn't for the faint hearted to operate, nor those with a pacemaker. Advice was also to never wear a watch when using it.

 

As you say definitely not for the faint hearted! it is quite a bit of power,.....a quick calculation shows about 500 turns of about 2mm dia., enamelled wire would do it, but it needs careful research. Hornby's unit had a warning about watches on a plate on it.

Also it took time to charge, and you had to allow it to cool off after a shot, before doing the next, it got very warm, so I am pretty sure they used a step down transformer, an inverted Tesla coil to create the pulse.

 

A battery flash unit should be safe, if a bit like a firework when used!! Such pulse magnetisers were common in garages in the 1920/30 period to re-magnetise Car and Bike Magnetos, in the days before generators and points came in to use in petrol engines.

 

Stephen.

[bertiedog]

Back on service details, under no circumstances use emery cloth or paper to clean up commutators, it leaves micro dust buried in the surface of the copper,........ use very fine glass paper or 3M pads to clean them, and polish with a soft cloth to finish. Clean out the gaps with a wooden point, it does not scratch the parts.

 

 

I find the best lube grease for Hornby is silicon grease loaded with PTFE, ( LaBelle make one, there are others). A good silicon oil can be used on the bearings and axles, the reason is silicon does not dry out unlike mineral oil.

Stephen.

 

[Il Grifone]

From the horse's mouth - The Meccano spec. for magnetising motors was 20,000 Gauss - hefty!

They quoted a loss of 20% in magnet strength from dismantling the motor.