Loco driving wheels

[CentralStation]

This photograph is the front set of driving wheels of my Hornby Class A3.  It's little over one year old, and I don't run it that often.  I try to keep the wheels clean through regular use of Woodland Scenics "Roto Wheel Cleaner", and I have never used anything abrasive (like those wheel cleaning brushes) or chemical.  I do use IPA to clean the track, but as it evaporates quickly, it's unlikely these wheels have ever picked up any IPA from the track.

 

I've just been doing some fault finding, as this loco has started being a bit "jerky" when running, and this is the first time I've looked closely at the wheels.  The phot shows that one (and only one) of the six driving wheels is looking yellow - all other wheels are fine.  The yellowing covers about 50% of the circumference of the wheel.  Close inspection reveals that this yellowing is not residue on the wheels, but appears to be that the plating is coming off, revealing a yellow metal underneath.  My thorough testing of this loco has revealed no mechanical issues, so, I now believe the poor running is due to this wheel.

 

So, my questions to any of you who might know:

 

1. Exactly what are these loco driving wheels made from.  It looks like it's brass or some other yellow metal casting, with a nickel? plating, but I just don't know.

2. Am I correct in my assumption that this wheel is now kaput, and possibly the cause of poor running?

 

Any help or information will be greatly appreciated.

 

[The Johnster]

I wouldn't say your wheel is completely kaput, but it does look as if the plating has worn off, and the fact that if has not worn evenly over the complete circumference suggests that this is a manufacturing fault, the plating not having been applied evenly.  Brass conducts electrickery fine, but will pick up crud and impair the pickup performance of the wheel, and thus running, especially slow running and smooth starting and stopping.  If it's over 1 year old, it will sadly be out of warranty, annoying on such a low mileage model but I would suggest contacting Hornby direct and seeing if they can help. 

 

They will be able to supply a replacement set of driving wheels, and replacement is not difficult, but is bit 'faffy'.  You will need to remove the crankpins holding the coupling and connecting rods to the wheels with a nut driver, then the plastic keeper plate, taking care not to pull on the wires running from the pickups to the inside of the loco.  The keeper plate screws are small and the crankpins are tiny, so don't lose them especially the crankpins.  I use a lump of Blutac to keep them from making a break for the border or sacrificing themselves to the carpet monster.

 

The old wheelset will now drop out and you can simply drop the new one in.  It needs to be the correct way around to engage the final driver gear.  Then you replace the coupling rods, with the little protrusions on the tops which represent the oil boxes facing upwards.  Then the connecting rods, which are fiddly because you have to carefully insert them into their holes in the rear of the cylinders; turning the motor over by hand using the flywheels will help here.  Then you replace the valve gear, and now you can replace the keeper plate, making sure the pickups bear correctly on the rear of the tyres.

 

You should be ready to test run the loco now, and it should run smoothly.  If it doesn't, one of us will probably be able to sort you out...

[melmerby]

If the wheel tread's plating is coming off due to poor adhesion to the under layer, you should be able to see an edge between the good and bad bits. I can't imagine it actually wearing off with such limited use.

The wheels wont be brass but just a casting which has had 2 or three different metals plated onto the base material to give the final finish.

 

e.g. when you chrome plate steel (such as an old style car bumper) it might have a base layer of copper, with a second of nickel, with a top coat of chrome

[micklner]

Before stripping the chassis.

 

A simple test is to connect two power leads, one to the wheel tread and one side of the motor, check all the drivers on that side , then check the other side, in case the fault is elsewhere . If they all work ok the problem is perhaps the motor, also check that all the  pick ups are all touching on the back of the wheels , before applying power. The Hornby pacifics pick ups are fairly weak and are easily bent away from the wheels , or never touched the back of the wheels in the first place !!.

[Nile]

The pick-ups that I can see look quite dirty and could do with a clean.

[DCB]

Looks like the pick up is nowhere near the back of the wheel. Usually works better when it actually touches the wheel.   I find wheels grip better when the plating has worn off but usually it takes 30 years not 30 yards.   Send it back and buy something GWR if you want trouble free running.

Only joking?

Edited August 18, 2021 by DavidCBroad

[CentralStation]

Thanks for your input Gents.  Much appreciated.

 

I will go for the low hanging fruit first - I'll adjust and give the pick-ups a good clean. That's something which I have neglected on all my models since I got the Woodland Scenics wheel cleaner thing, but I'm convinced pick ups are not the issue, as this model picks up from all 6 driving wheels and the 8 tender wheels, and it seems to run beautifully when on the wheel cleaner (i.e. when I don't need traction).  I will also check each wheel to make sure they are all picking up power.

Hopefully I can sort this without having to replace the motor (which seems to be a bit rare right now - even Peter's Spares are out of stock), or the wheelset.

 

And special thanks to DavidCBroad, but, although the GWR may have been wonderful, it is not an option .

 

Thanks again everyone.  I'll post an update when/if I make progress.

 

 

[melmerby]

1 hour ago, micklner said:

 

 

. The Hornby pacifics steam loco pick ups are fairly weak and are easily bent away from the wheels , or never touched the back of the wheels in the first place !!.

A bit more general than just pacifics, I have just had much frustration with a Stanier 4P tank, which kept stopping due to lost rail contact (I use electrofrog pointwork and every bit is powered.)

I have two 4Ps and only one was causing trouble, mostly due to pickup problems.

[The Johnster]

Pickups and the rear surface of the wheel rim that they bear against need to be as clean as the wheel/rail interface, and as has been said Hornby pickups are delicate little wallflowers that need careful ‘adjustment’, i.e. bending.  Make sure that they bear against the rim back throughout the range of sideways play that each axle has. 
 

If the motor runs well on the wheel cleaner, or with current applied directly to the terminals, it is clearly fine and doesn’t need replacing; indeed, were you to replace it, there would be no improvement in the running.  

[melmerby]

3 minutes ago, 313201 said:

Recently, I have been adding my self made pickups on my locos so that they touch the tread of the wheels and not the backs of them.

 

 

Can't see any point in that.

IMHO Decent pickups bearing on the back of the wheel are as good as anything barring modern split axle contacts.

[Jeff Smith]

Flat pick-ups bearing on a flat surface such as a wheel back are the least efficient and prone to trap dirt which can break the contact.  The best type of pick up has minimal contact area for maximum contact pressure, ie bearing onto the edge of the wheel flange or a contact with a bent end so that only the tip bears onto the wheel back or tread.

[micklner]

I dont bother with Tender pick ups on Pacific Locos .

 

A long wheelbase and six wheels are more than enough for current collection.

 

Hornby I believe are the only r.t.r maker who fits them . They act more as brakes than  current collectors and often squeak as well . I simply bend them away from the wheels.

[melmerby]

49 minutes ago, Jeff Smith said:

Flat pick-ups bearing on a flat surface such as a wheel back are the least efficient and prone to trap dirt which can break the contact.  The best type of pick up has minimal contact area for maximum contact pressure, ie bearing onto the edge of the wheel flange or a contact with a bent end so that only the tip bears onto the wheel back or tread.

Hornby ones have a dimple on the end so it is effectively a point contact. Gone are the days of Triang flat contacts

[CentralStation]

Just to put this one to bed...

 

Following the advice of members, I tried picking at the cusp of the discoloured and normal parts, under the highest magnification I have, and there is no edge.  I now believe the wheel is just tarnished, rather than damaged.  I can't see why only one wheel on one loco?

 

Anyway, I fully cleaned all wheels, including back faces and pickups, with IPA and cotton buds.  I also thought I'd check the gearing while I was in there, which is now fully cleaned and re-greased.  After putting it back together, I tested each wheel to make sure they were picking up current, and all of them are.

 

While doing the above I noticed the clumsy nature of the lubrication (factory applied).  After removing the base plate of the chassis, for easier access to the pick ups, there seemed to be an awful lot of oil coating the base, including the parts of the pick ups which sit in the base.  Now, I'm no physicist, but oil is a liquid, and liquids tend to run into any nook or cranny, so, this excess oil could quite easily have made it's way down the pick ups.  As oil is not a very good conductor of electrickery, this may have been causing some issues.

There was also far too much grease on the gearing under the motor's worm - a stray grain of loose ballast or something, getting stuck in there wouldn't help - although I'm not sure if that is possible.

 

So, with everything cleaned, lubricated (sparingly!)  and put back together, my A3 is running much better.  I'm not convinced it is running as good as it once did.  I'm sure I see a little stutter now and then - perhaps a little wheel-slip due to the tarnished wheel,  but then again, maybe I'm now just looking for issues, rather than being dazzled by this beautiful model.   

 

Thanks for your input.  It was very much appreciated.

[melmerby]

20 hours ago, CentralStation said:

Just to put this one to bed...

 

While doing the above I noticed the clumsy nature of the lubrication (factory applied).  After removing the base plate of the chassis, for easier access to the pick ups, there seemed to be an awful lot of oil coating the base, including the parts of the pick ups which sit in the base.  Now, I'm no physicist, but oil is a liquid, and liquids tend to run into any nook or cranny, so, this excess oil could quite easily have made it's way down the pick ups.  As oil is not a very good conductor of electrickery, this may have been causing some issues.

There was also far too much grease on the gearing under the motor's worm - a stray grain of loose ballast or something, getting stuck in there wouldn't help - although I'm not sure if that is possible.

 

 

Thanks for your input.  It was very much appreciated.

Bachmann use a grease a bit like soft butter, unfortunately over time it can become very hard and tacky and therefore is no furtrher use as a lubrication.

Something to look out for if a Bachmann loco is giving problems.

 

[Michael Hodgson]

One tarnished wheel won't cause wheel slip - as the driving wheels are coupled all or none of them will slip.

If you're still getting stutter and the wheels and pickups are all clean, then it must be the rail that's dirty

[Jeff Smith]

Dirty rail can account for a lot - fairly easy to diagnose if it happens repeatedly in the same spot(s), especially after pushing the loco so different tyre surfaces are tested.

[John Tomlinson]

On 23/08/2021 at 19:07, CentralStation said:

Just to put this one to bed...

 

Following the advice of members, I tried picking at the cusp of the discoloured and normal parts, under the highest magnification I have, and there is no edge.  I now believe the wheel is just tarnished, rather than damaged.  I can't see why only one wheel on one loco?

 

Anyway, I fully cleaned all wheels, including back faces and pickups, with IPA and cotton buds.  I also thought I'd check the gearing while I was in there, which is now fully cleaned and re-greased.  After putting it back together, I tested each wheel to make sure they were picking up current, and all of them are.

 

While doing the above I noticed the clumsy nature of the lubrication (factory applied).  After removing the base plate of the chassis, for easier access to the pick ups, there seemed to be an awful lot of oil coating the base, including the parts of the pick ups which sit in the base.  Now, I'm no physicist, but oil is a liquid, and liquids tend to run into any nook or cranny, so, this excess oil could quite easily have made it's way down the pick ups.  As oil is not a very good conductor of electrickery, this may have been causing some issues.

There was also far too much grease on the gearing under the motor's worm - a stray grain of loose ballast or something, getting stuck in there wouldn't help - although I'm not sure if that is possible.

 

So, with everything cleaned, lubricated (sparingly!)  and put back together, my A3 is running much better.  I'm not convinced it is running as good as it once did.  I'm sure I see a little stutter now and then - perhaps a little wheel-slip due to the tarnished wheel,  but then again, maybe I'm now just looking for issues, rather than being dazzled by this beautiful model.   

 

Thanks for your input.  It was very much appreciated.

 

Excess oil and/or grease applied at the factory is sadly a problem that is all too common.

 

I reached the stage some while ago that I investigate all new arrivals (usually pre-owned), and give them a clean before turning a wheel, other than an initial trundle on my test track. I check pick-ups, tread backs and wheel back to backs at the same time. I've found this is a time saver in the long run, and means that my track isn't being coated in grot, which then goes onto other locos, and all running is better as a result.

 

I do find it is very easy to run a loco and look for faults, rather than actually enjoy it, and it sounds as if that may be your experience too!

 

John.

[DCB]

Eventually you get to the point where if you run a loco and if it runs well you change it for another till you find one which does not and you then spend the rest of the session fixing it instead of running trains. This condition is incurable and if presented with only locos which work perfectly sufferers then set about weathering and kit building to ensure the supply of hassle outstrips the time available for fixing the issues.